AXT (AXTI) 10-Q 9 May 22 2022 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2022	May 01, 2022
Document And Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2022
Document Transition Report	false
Entity File Number	000-24085
Entity Registrant Name	AXT INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	94-3031310
Entity Address, Address Line One	4281 Technology Drive
Entity Address, City or Town	Fremont
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94538
City Area Code	510
Local Phone Number	438-4700
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	AXTI
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		42,951,852
Entity Central Index Key	0001051627
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 29,494	$ 36,763
Short-term investments	5,400	5,419
Accounts receivable, net of allowances of $130 as of March 31, 2022 and December 31, 2021	39,848	34,839
Inventories	68,821	65,912
Prepaid expenses and other current assets	16,501	17,252
Total current assets	160,064	160,185
Long-term investments	9,400	9,576
Property, plant and equipment, net	147,286	142,415
Operating lease right-of-use assets	2,223	2,324
Other assets	19,426	17,941
Total assets	338,399	332,441
Current liabilities:
Accounts payable	14,399	16,649
Accrued liabilities	12,213	17,057
Short-term loan from noncontrolling interest		1,887
Bank loan	20,192	12,229
Total current liabilities	46,804	47,822
Noncurrent operating lease liabilities	1,810	1,935
Other long-term liabilities	2,263	2,453
Total liabilities	50,877	52,210
Commitments and contingencies (Note 12)
Redeemable noncontrolling interests (Note 18)	50,971	50,385
Stockholders' equity:
Preferred stock Series A, $0.001 par value; 2,000 shares authorized; 883 shares issued and outstanding as of March 31, 2022 and December 31, 2021 (Liquidation preference of $7,566 and $7,522 as of March 31, 2022 and December 31, 2021)	3,532	3,532
Common stock, $0.001 par value; 70,000 shares authorized; 42,952 and 42,886 shares issued and outstanding as of March 31, 2022 and December 31, 2021	43	43
Additional paid-in capital	232,317	231,622
Accumulated deficit	(26,805)	(29,970)
Accumulated other comprehensive income	6,629	6,302
Total AXT, Inc. stockholders' equity	215,716	211,529
Noncontrolling interests	20,835	18,317
Total stockholders' equity	236,551	229,846
Total liabilities, redeemable noncontrolling interests and stockholders' equity	$ 338,399	$ 332,441

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Accounts receivable, allowances for doubtful accounts	$ 130	$ 130
Stockholders' equity:
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	2,000,000	2,000,000
Preferred stock, shares issued (in shares)	883,000	883,000
Preferred stock, shares outstanding (in shares)	883,000	883,000
Preferred stock, liquidation preference	$ 7,566	$ 7,522
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	70,000,000	70,000,000
Common stock, shares issued (in shares)	42,952,000	42,886,000
Common stock, shares outstanding (in shares)	42,952,000	42,886,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
Revenue	$ 39,653	$ 31,350
Cost of revenue	26,345	19,814
Gross profit	13,308	11,536
Operating expenses:
Selling, general and administrative	6,450	5,570
Research and development	3,159	2,405
Total operating expenses	9,609	7,975
Income from operations	3,699	3,561
Interest expense, net	(183)	(50)
Equity in income of unconsolidated joint ventures	1,125	1,111
Other expense, net	(9)	(111)
Income before provision for income taxes	4,632	4,511
Provision for income taxes	660	746
Net income	3,972	3,765
Less: Net income attributable to noncontrolling interests and redeemable noncontrolling interests	(807)	(340)
Net income attributable to AXT, Inc.	$ 3,165	$ 3,425
Net income attributable to AXT,Inc. per common share:
Basic	$ 0.07	$ 0.08
Diluted	$ 0.07	$ 0.08
Weighted-average number of common shares outstanding:
Basic	41,871	41,004
Diluted	42,662	42,726

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income	$ 3,972	$ 3,765
Other comprehensive income (loss), net of tax:
Change in foreign currency translation gain (loss), net of tax	590	(156)
Change in unrealized loss on available-for-sale debt investments, net of tax	(172)	(8)
Total other comprehensive income (loss), net of tax	418	(164)
Comprehensive income	4,390	3,601
Less: Comprehensive income attributable to noncontrolling interests and redeemable noncontrolling interests	(898)	(307)
Comprehensive income attributable to AXT, Inc.	$ 3,492	$ 3,294

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net income	$ 3,972	$ 3,765
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	1,983	1,596
Amortization of marketable securities premium	23	15
Stock-based compensation	1,088	816
Gain on disposal of equipment	24	2
Equity in income of unconsolidated joint ventures	(1,125)	(1,111)
Deferred tax assets	(8)
Changes in operating assets and liabilities:
Accounts receivable	(4,915)	(3,886)
Inventories	(2,586)	(3,243)
Prepaid expenses and other current assets	810	(2,818)
Other assets	(341)	135
Accounts payable	(2,299)	745
Accrued liabilities	(4,867)	(4,018)
Other long-term liabilities, including royalties	(665)	(307)
Net cash used in operating activities	(8,906)	(8,309)
Cash flows from investing activities:
Purchases of property, plant and equipment	(6,294)	(5,776)
Proceeds from sales and maturities of available-for-sale debt securities		240
Net cash used in investing activities	(6,294)	(5,536)
Cash flows from financing activities:
Proceeds from common stock options exercised		704
Proceeds from sale of subsidiary shares to noncontrolling interests		538
Proceeds from bank loan	10,718
Payments on bank loan	(2,799)
Formation of new subsidiary with noncontrolling interests		642
Proceeds from issuance of Tongmei's common stock to redeemable noncontrolling interests, net of costs		730
Net cash provided by financing activities	7,919	2,614
Effect of exchange rate changes on cash and cash equivalents	12	(165)
Net decrease in cash and cash equivalents	(7,269)	(11,396)
Cash and cash equivalents at the beginning of the year	36,763	72,602
Cash and cash equivalents at the end of the period	29,494	61,206
Supplemental disclosure of non-cash flow information:
Conversion of related party borrowings to Additional Paid-in Capital	1,887
Investment in subsidiary shares from noncontrolling interest	$ 410
Consideration payable to repurchase subsidiary shares from noncontrolling interests, included in accrued liabilities		$ 3,730

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2022
Basis of Presentation
Basis of Presentation	Note 1. Basis of Presentation ​ The accompanying condensed consolidated financial statements of AXT, Inc. (“AXT,” the “Company,” “we,” “us,” and “our” refer to AXT, Inc. and all of its consolidated subsidiaries) are unaudited, and have been prepared in accordance with accounting principles generally accepted in the United States of America (“US GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, this interim quarterly financial report does not include all disclosures required by US GAAP. In the opinion of our management, the unaudited condensed consolidated financial statements reflect all adjustments, consisting only of normal recurring adjustments, considered necessary to present fairly the financial position, results of operations and cash flows of AXT and our consolidated subsidiaries for all periods presented. ​ Our management has made a number of estimates and assumptions relating to the reporting of assets and liabilities and the disclosure of contingent assets and liabilities to prepare these condensed consolidated financial statements in conformity with US GAAP. Due to the COVID-19 pandemic, there has been uncertainty and disruption in the global economy and financial markets. These estimates and assumptions may change as new events occur and additional information is obtained. Actual results could differ materially from those estimates. ​ The results of operations for the three months ended March 31, 2022 are not necessarily indicative of the results to be expected in the future or for the full fiscal year. It is recommended that these condensed consolidated financial statements be read in conjunction with our consolidated financial statements and the notes thereto included in our 2021 Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on March 15, 2022. ​ The condensed consolidated financial statements include the accounts of AXT, and our consolidated subsidiaries, Beijing Tongmei Xtal Technology Co., Ltd. (“Tongmei”), AXT-Tongmei, Inc. (“AXT-Tongmei”), Baoding Tongmei Xtal Technology Co., Ltd. (“Baoding Tongmei”), ChaoYang Tongmei Xtal Technology Co., Ltd. (“ChaoYang Tongmei”), ChaoYang LiMei Semiconductor Technology Co., Ltd. (“ChaoYang LiMei”), ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd. (“ChaoYang XinMei”), Nanjing JinMei Gallium Co., Ltd. (“JinMei”), ChaoYang JinMei Gallium Ltd. (“ChaoYang JinMei”), MaAnShan JinMei Gallium Ltd., and Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd. (“BoYu”). All significant inter-company accounts and transactions have been eliminated. Investments in business entities in which we do not have controlling interests, but have the ability to exercise significant influence over operating and financial policies (generally 20-50% ownership), are accounted for by the equity method. As of March 31, 2022 and December 31, 2021, we have five companies accounted for by the equity method. For the majority-owned subsidiaries that we consolidate, we reflect the portion we do not own as either noncontrolling interests in stockholder’s equity or as redeemable noncontrolling interests in temporary equity on our condensed consolidated balance sheets and in our condensed consolidated statements of operations. ​ When market conditions are warranted, we intend to construct facilities at the ChaoYang LiMei location to provide us with additional production capacity. For the three months ended March 31, 2022, expenses associated with ChaoYang LiMei had a de minimis impact on our condensed consolidated financial statements. ​ In February 2021, Tongmei signed a joint venture agreement with certain investors to fund a new company, ChaoYang XinMei. The agreement called for a total investment of approximately $3.0 million, of which Tongmei would fund approximately $1.8 million for a 58.5 percent ownership of ChaoYang XinMei. In February 2021, the investors completed the initial funding of approximately $1.5 million. Tongmei’s portion of the investment was approximately $0.9 million. In May 2021, the investors completed the funding of the remaining balance of approximately $1.5 million. Tongmei’s portion of the final investment was approximately $0.9 million, for a total investment of approximately $1.8 million for a 58.5 percent ownership of ChaoYang XinMei. In September 2021 and October 2021, ChaoYang XinMei received funding from a minority investor of $0.9 million and $1.0 million, respectively. In December 2021 and January 2022, ChaoYang XinMei received funding from Tongmei of $1.4 million and $1.4 million, respectively. In January 2022, the China local government certified this additional funding in ChaoYang XinMei, as an equity investment. Tongmei’s ownership remained at 58.5% after these equity investments. ​ During the quarter ended December 31, 2020, Tongmei entered into two sets of definitive transaction documents, each consisting of a capital increase agreement along with certain supplemental agreements in substantially the same form (collectively, the “Capital Investment Agreements”), with several private equity investors in China. ​ In preparation for Tongmei’s application for a listing of shares in an initial public offering (the “IPO”) on the Shanghai Stock Exchange’s Sci-Tech innovAtion boaRd (the “STAR Market”), in late December 2020, we reorganized our entity structures in China. JinMei and BoYu and its subsidiaries were assigned to Tongmei and effectively merged with Tongmei although they retained their own respective legal entity status and are wholly owned subsidiaries of Tongmei. The minority interest in Tongmei. The

Investments and Fair Value Meas

Investments and Fair Value Measurements	3 Months Ended
	Mar. 31, 2022
Investments and Fair Value Measurements
Investments and Fair Value Measurements	Note 2. Investments and Fair Value Measurements ​ Our cash and cash equivalents consist of cash and instruments with original maturities of less than three months. Our investments consist of instruments with original maturities of more than three months. As of March 31, 2022 and December 31, 2021, our cash, cash equivalents and debt investments are classified as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2022 ​ December 31, 2021 ​ ​ ​ Gross Gross ​ ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Cost Gain (Loss) Value Cost Gain (Loss) Value Classified as: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash ​ $ 29,494 ​ $ — ​ $ — ​ $ 29,494 ​ $ 36,763 ​ $ — ​ $ — ​ $ 36,763 ​ Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit 1 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Total cash and cash equivalents ​ 29,494 ​ — ​ — ​ 29,494 ​ 36,763 ​ — ​ — ​ 36,763 ​ Investments (available-for-sale): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit 2 ​ 6,680 ​ — ​ ​ (90) ​ 6,590 ​ 6,680 ​ — ​ ​ (19) ​ 6,661 ​ Corporate bonds ​ 8,357 ​ — ​ (147) ​ 8,210 ​ 8,380 ​ — ​ (46) ​ 8,334 ​ Total investments ​ 15,037 ​ — ​ (237) ​ 14,800 ​ 15,060 ​ — ​ (65) ​ 14,995 ​ Total cash, cash equivalents and investments ​ $ 44,531 ​ $ — ​ $ (237) ​ $ 44,294 ​ $ 51,823 ​ $ — ​ $ (65) ​ $ 51,758 ​ Contractual maturities on investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Due within 1 year 3 ​ $ 5,409 ​ ​ ​ ​ ​ ​ ​ $ 5,400 ​ $ 5,424 ​ ​ ​ ​ ​ ​ ​ $ 5,419 ​ Due after 1 through 5 years 4 ​ 9,627 ​ ​ ​ ​ ​ ​ ​ 9,400 ​ 9,636 ​ ​ ​ ​ ​ ​ ​ 9,576 ​ ​ ​ $ 15,036 ​ ​ ​ ​ ​ ​ ​ $ 14,800 ​ $ 15,060 ​ ​ ​ ​ ​ ​ ​ $ 14,995 ​ 1. Certificates of deposit with original maturities of less than three months. 2. Certificates of deposit with original maturities of more than three months. 3. Classified as “Short-term investments” in our condensed consolidated balance sheets. 4. Classified as “Long-term investments” in our condensed consolidated balance sheets. ​ ​ We manage our debt investments as a single portfolio of highly marketable securities that is intended to be available to meet our current cash requirements. Certificates of deposit and corporate bonds are typically held until maturity. ​ Historically, the gross unrealized losses related to our portfolio of available-for-sale debt securities were immaterial, and primarily due to normal market fluctuations and not due to increased credit risk or other valuation concerns. There was an insignificant amount of gross unrealized losses on our available-for-sale debt securities as of March 31, 2022, and historically, such gross unrealized losses have been temporary in nature and we believe that it is probable the principal and interest will be collected in accordance with the contractual terms. We review our debt investment portfolio at least quarterly, or when there are changes in credit risks or other potential valuation concerns, to identify and evaluate whether an allowance for credit losses or impairment would be necessary. Factors considered in determining whether a loss is temporary include the magnitude of the decline in market value, the length of time the market value has been below cost (or adjusted cost), credit quality, and our ability and intent to hold the securities for a period of time sufficient to allow for any anticipated recovery in market value. ​ A portion of our debt investments would generate a loss if we sold them on March 31, 2022. The following table summarizes the fair value and gross unrealized losses related to available-for-sale debt securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of March 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ In Loss Position ​ In Loss Position ​ Total In ​ ​ < 12 months ​ > 12 months ​ Loss Position ​ ​ ​ ​ ​ Gross ​ ​ ​ ​ Gross ​ ​ ​ ​ Gross ​ ​ Fair ​ Unrealized ​ Fair ​ Unrealized ​ Fair ​ Unrealized As of March 31, 2022 Value (Losses) Value (Losses) Value (Losses) Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ $ 6,590 ​ $ (90) ​ $ — ​ $ — ​ $ 6,590 ​ $ (90) ​ Corporate bonds ​ 4,857 ​ (139) ​ 3,002 ​ (7) ​ 7,859 ​ ​ (146) ​ Total in loss position ​ $ 11,447 ​ $ (229) ​ $ 3,002 ​ $ (7) ​ $ 14,449 ​ $ (236) ​ ​ ​ The following table summarizes the fair value and gross unrealized losses related to available-for-sale debt securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ In Loss Position ​ In Loss Position ​ Total In ​ ​ < 12 months ​ > 12 months ​ Loss Position ​ ​ Gross ​ Gross ​ Gross ​ ​ Fair ​ Unrealized ​ Fair ​ Unrealized ​ Fair ​ Unrealized As of December 31, 2021 ​ Value ​ (Loss) ​ Value ​ (Loss) ​ Value ​ (Loss) Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ $ 6,181 ​ $ (19) ​ $ — ​ $ — ​ $ 6,181 ​ $ (19) ​ Corporate bonds ​ 5,970 ​ (42) ​ 2,013 ​ (4) ​ 7,983 ​ ​ (46) ​ Total in loss position ​ $ 12,151 ​ $ (61) ​ $ 2,013 ​ $ (4) ​ $ 14,164 ​ $ (65) ​ ​ Investments in Privately-held Raw Material Companies ​ We have made strategic investments in private companies located in China in order to gain access at a competitive cost to raw materials that are critical to our substrate business (see Note 7). The investment balances for the non-consolidated companies are accounted for under the equity method and included in “Other assets” in the condensed consolidated balance sheets and totaled $11.3 million and $10.2 million as of March 31, 2022 and December 31, 2021, respectively. As of March 31, 2022, there were five companies accounted for under the equity method. There were no impairment charges in the three months ended March 31, 2022 and 2021. ​ Fair Value Measurements ​ We invest primarily in money market accounts, certificates of deposits, corporate bonds and notes, and government securities. We review our debt investment portfolio for credit loss at least quarterly or when there are changes in credit risk or other potential valuation concerns. As of March 31, 2022 and December 31, 2021, the total unrealized loss, net of tax, included in accumulated other comprehensive income was immaterial. We believe it is probable the principal and interest will be collected in accordance with the contractual terms, and the unrealized loss on these securities was due to normal market fluctuations, and not due to increased credit risk or other valuation concerns. Accounting Standards Codification (“ASC”) Topic 820, Fair Value Measurements and Disclosures ​ The type of instrument valued based on quoted market prices in active markets include our money market funds, which are generally classified within Level 1 of the fair value hierarchy. We classify our available-for-sale debt securities including certificates of deposit and corporate bonds as having Level 2 inputs. The valuation techniques used to measure the fair value of these financial instruments having Level 2 inputs were derived from bank statements, quoted market prices, broker or dealer statements or quotations, or alternative pricing sources with reasonable levels of price transparency. ​ We place short-term foreign currency hedges that are intended to offset the potential cash exposure related to fluctuations in the exchange rate between the United States dollar and Japanese yen. We measure the fair value of these foreign currency hedges at each month end and quarter end using current exchange rates and in accordance with US GAAP. At quarter end, any foreign currency hedges not settled are netted in “Accrued liabilities” on the condensed consolidated balance sheet and classified as Level 3 assets and liabilities. As of March 31, 2022, the net change in fair value from the placement of the hedge to settlement at each month end during the quarter had a de minimis impact on the condensed consolidated results. ​ There were no changes in valuation techniques or related inputs in the three months ended March 31, 2022. There have been no transfers between fair ​ The following table summarizes our financial assets and liabilities measured at fair value on a recurring basis in accordance with ASC 820 as of Mach 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices in ​ ​ ​ Significant ​ ​ ​ ​ ​ Active Markets of ​ Significant Other ​ Unobservable ​ ​ Balance as of ​ Identical Assets ​ Observable Inputs ​ Inputs ​ March 31, 2022 (Level 1) (Level 2) (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents and investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ $ 6,590 ​ $ — ​ $ 6,590 ​ $ — ​ Corporate bonds ​ 8,210 ​ — ​ 8,210 ​ — ​ Total ​ $ 14,800 ​ $ — ​ $ 14,800 ​ $ — ​ ​ The following table summarizes our financial assets and liabilities measured at fair value on a recurring basis in accordance with ASC 820 as of December 31, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices in ​ ​ ​ Significant ​ ​ ​ ​ ​ Active Markets of ​ Significant Other ​ Unobservable ​ ​ Balance as of ​ Identical Assets ​ Observable Inputs ​ Inputs ​ December 31, 2021 (Level 1) (Level 2) (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents and investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ $ 6,661 ​ $ — ​ $ 6,661 ​ $ — ​ Corporate bonds ​ 8,334 ​ — ​ 8,334 ​ — ​ Total ​ $ 14,995 ​ $ — ​ $ 14,995 ​ $ — ​ ​ Items Measured at Fair Value on a Nonrecurring Basis ​ Certain assets that are subject to nonrecurring fair value measurements are not included in the table above. These assets include investments in privately-held companies accounted for by the equity or cost method (see Note 7). We did not record any other-than-temporary impairment charges for these investments during the three months ended March 31, 2022 and 2021, respectively.

Inventories

Inventories	3 Months Ended
	Mar. 31, 2022
Inventories
Inventories	Note 3. Inventories ​ The components of inventories are summarized below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ ​ 2022 2021 Inventories: ​ ​ ​ ​ ​ ​ ​ Raw materials ​ $ 32,949 ​ $ 29,658 ​ Work in process ​ 32,411 ​ 32,605 ​ Finished goods ​ 3,461 ​ 3,649 ​ ​ ​ $ 68,821 ​ $ 65,912 ​ ​ As of March 31, 2022 and December 31, 2021, carrying values of inventories were net of inventory reserves of $20.6 million and $19.6 million, respectively, for excess and obsolete inventory and $70,000 and $66,000, respectively, for lower of cost or net realizable value reserves.

Property, Plant and Equipment,

Property, Plant and Equipment, Net	3 Months Ended
	Mar. 31, 2022
Property, Plant and Equipment, Net
Property, Plant and Equipment, Net	Note 4. Property, Plant and Equipment, Net ​ The components of our property, plant and equipment are summarized below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ ​ ​ 2022 ​ 2021 ​ Property, plant and equipment: ​ ​ ​ ​ ​ ​ ​ Machinery and equipment, at cost ​ $ 59,617 ​ $ 59,284 ​ Less: accumulated depreciation and amortization ​ ​ (40,848) ​ ​ (40,292) ​ Building, at cost ​ ​ 109,071 ​ ​ 108,782 ​ Less: accumulated depreciation and amortization ​ ​ (19,560) ​ ​ (18,710) ​ Leasehold improvements, at cost ​ 7,060 ​ 7,039 ​ Less: accumulated depreciation and amortization ​ ​ (5,521) ​ ​ (5,352) ​ Construction in progress ​ 37,467 ​ 31,664 ​ ​ ​ $ 147,286 ​ $ 142,415 ​ ​ As of March 31, 2022, the balance of construction in progress was $37.5 million, of which $27.2 million was related to our buildings in our new Dingxing and Kazuo locations, $4.3 million was for manufacturing equipment purchases not yet placed in service and $6.1 million was for construction in progress for our other consolidated subsidiaries. As of December 31, 2021, the balance of construction in progress was $31.7 million, of which $22.7 million was for our buildings in our new Dingxing and Kazuo locations, $3.0 million was for manufacturing equipment purchases not yet placed in service and $6.0 million was for our construction in progress at our other consolidated subsidiaries.

Accrued Liabilities

Accrued Liabilities	3 Months Ended
	Mar. 31, 2022
Accrued Liabilities
Accrued Liabilities	Note 5. Accrued Liabilities ​ The components of accrued liabilities are summarized below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ ​ 2022 2021 Accrued compensation and related charges ​ $ 3,436 ​ $ 5,115 ​ Preferred stock dividends payable ​ ​ 2,901 ​ ​ 2,901 ​ Advances from customers ​ ​ 1,024 ​ ​ 946 ​ Accrued income taxes ​ ​ 1,001 ​ ​ 539 ​ Accrued product warranty ​ ​ 832 ​ ​ 743 ​ Current portion of operating lease liabilities ​ ​ 499 ​ ​ 488 ​ Accrued professional services ​ ​ 423 ​ ​ 880 ​ Other personnel-related costs ​ ​ 278 ​ ​ 279 ​ Payable in connection with construction in progress ​ ​ 268 ​ ​ 2,974 ​ Other tax payable ​ ​ 230 ​ ​ 392 ​ Accrual for sales returns ​ ​ 20 ​ ​ 48 ​ Other accrued liabilities ​ ​ 1,301 ​ ​ 1,752 ​ ​ ​ $ 12,213 ​ $ 17,057 ​ ​

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2022
Related Party Transactions
Related Party Transactions	Note 6. Related Party Transactions ​ In March 2012, Tongmei, entered into an operating lease for the land it owns with our consolidated subsidiary, BoYu. The lease agreement for the land of approximately 22,081 square feet commenced on January 1, 2012 for a term of 10 years with annual lease payments of $24,000, subject to a 5% increase at each third year anniversary. The annual lease payment is due by January 31 st ​ ChaoYang Tongmei purchases raw materials from one of our equity investment entities, Donghai County Dongfang High Purity Electronic Materials Co., Ltd., for production in the ordinary course of business. As of March 31, 2022 and December 31, 2021, amounts payable of $112,000 and $112,000 , respectively, were included in “Accounts payable” in our condensed consolidated balance sheets. ​ In July 2017, Tongmei, provided an inter-company loan to JinMei in the amount of $768,000 in preparation for the acquisition of the land use rights and the construction of a new building. The inter-company loan carries an interest rate of 4.9% per annum. The principal . ​ In September 2021 and October 2021, our consolidated subsidiary, ChaoYang XinMei received funding from a minority investor of $0.9 million and $1.0 million, respectively. In December 2021 and January 2022, the same subsidiary received funding from Tongmei of $1.4 million and $1.4 million, respectively. In January 2022, the China local government certified this additional funding in our consolidated subsidiary, ChaoYang XinMei, as an equity investment. As a result, noncontrolling interests increased $2.2 million and redeemable noncontrolling interests increased $0.2 million. Short-term loan from noncontrolling interest decreased to $0. Tongmei’s ownership remained at 58.5% after these equity investments. As of March 31, 2022, $0 was included in “Long-term debt, related party” in our condensed consolidated balance sheets. ​ Our Related Party Transactions Policy seeks to prohibit all conflicts of interest in transactions between related parties and us, unless they have been approved by our Board of Directors. This policy applies to all of our employees, directors, and our consolidated subsidiaries. Our executive officers retain board seats on the board of directors of the companies in which we have invested in our China joint ventures. See Note 7 for further details. ​

Investments in Privately-Held R

Investments in Privately-Held Raw Material Companies	3 Months Ended
	Mar. 31, 2022
Investments in Privately-Held Raw Material Companies
Investments in Privately-Held Raw Material Companies	Note 7. Investments in Privately-Held Raw Material Companies ​ We have made strategic investments in private companies located in China in order to gain access at a competitive cost to raw materials that are critical to our substrate business. These companies form part of our overall supply chain strategy. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Investment Balance as of ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ Accounting ​ Ownership * Company 2022 2021 Method Percentage ​ Nanjing JinMei Gallium Co., Ltd. ​ $ 592 ​ $ 592 Consolidated **85.5 % ChaoYang JinMei Gallium Co., Ltd. ​ ​ 1,820 ​ ​ 1,820 ​ Consolidated ​ **85.5 % Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd. ​ 1,346 ​ 1,346 Consolidated **85.5 % ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd. ​ ​ 4,642 ​ ​ 1,814 ​ Consolidated ***58.5 % ​ ​ $ 8,400 ​ $ 5,572 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Donghai County Dongfang High Purity Electronic Materials Co., Ltd. ​ $ 2,057 ​ $ 2,053 Equity **46 % Beijing JiYa Semiconductor Material Co., Ltd. ​ ​ 4,292 ​ ​ 3,760 ​ Equity ​ 39 % Xilingol Tongli Germanium Co., Ltd. ​ — ​ — Equity 25 % Xiaoyi XingAn Gallium Co., Ltd. ​ ​ 4,739 ​ ​ 4,095 ​ Equity ​ **25 % Emeishan Jia Mei High Purity Metals Co., Ltd. ​ 224 ​ 258 Equity 25 % ​ ​ $ 11,312 ​ $ 10,166 ​ ​ ​ ​ ​ ​ * These ​ ** In preparation for Tongmei’s application for a listing of shares in an IPO on the STAR Market, in late December 2020 we reorganized our entity structures in China. JinMei and BoYu and its subsidiaries, previously organized under AXT, Inc., were assigned to Tongmei and effectively merged with Tongmei although they retained their own respective legal entity status and are wholly owned subsidiaries of Tongmei. The minority interest in Tongmei. The ​ *** ​ Before June 15, 2018, our ownership of JinMei was 83%. On June 15, 2018, we purchased a 12% ownership interest from one of the minority owners of JinMei for $1.4 million. The $1.4 million was scheduled to be paid in two installments. On June 15, 2018, we paid the first installment of $163,000. In May 2019, we paid the second installment of $1.2 million as the relocation of JinMei’s headquarters and manufacturing operations was nearly complete, which had been previously included in “Accrued liabilities” in our condensed consolidated balance sheets. As a result, our ownership of JinMei increased from 83% to 95%. In September 2018, we purchased a 2% ownership interest from one of the three remaining minority owners of JinMei for $252,000. As a result, our ownership of JinMei increased from 95% to 97%. In May 2019, we purchased the remaining 3% ownership interest from retiring members of the JinMei management team for approximately $413,000. The final payment to the JinMei management team was made in October, 2020. As a result, our ownership of JinMei increased from 97% to 100%. Prior to June 1, 2019, we reported JinMei as a consolidated joint venture as we had a controlling financial interest and have majority control of the board. As of June 1, 2019, we referred to it as a wholly-owned subsidiary and reduced the carrying value of the corresponding noncontrolling interests to zero. Before August 1, 2020, our ownership of ChaoYang JinMei was 100%. In August 2020, we sold an 8.5% ownership interest to current members of the ChaoYang JinMei management team for approximately $396,000. As a result, our ownership of ChaoYang JinMei decreased from 100% to 91.5%. As of August 2020, we referred to ChaoYang JinMei as a significantly controlled subsidiary instead of a wholly-owned subsidiary. Our Chief Executive Officer is chairman of the JinMei board and we have appointed two other representatives to serve on the JinMei board. ​ Our ownership of BoYu was 67%. On November 2, 2017, BoYu raised additional capital in the amount of $2 million in cash from a third-party investor through the issuance of shares equivalent to 10% ownership of BoYu. As a result, our ownership of BoYu was diluted from 70% to 63%. In December 2020, we purchased shares equivalent to 4% of BoYu from the same third-party investor for $1.6 million. As a result, our ownership of BoYu increased from 63% to 67%. We continue to consolidate BoYu as we have a controlling financial interest and have majority control of the board and accordingly no gain was recognized as a result of this equity transaction. Our Chief Executive Officer is chairman of the BoYu board and we have appointed two other representatives to serve on the board. An additional step in the STAR Market IPO process involved certain entity reorganizations and alignment of assets under Tongmei. In this regard our two consolidated raw material companies, JinMei and BoYu, and its subsidiaries, were assigned to Tongmei in December 2020. This increased the number of customers and employees attributable to Tongmei as well as increased Tongmei’s consolidated revenue. Although we have representation on the board of directors of each of the privately held raw material companies, the daily operations of each of these companies are managed by local management and not by us. Decisions concerning their respective short-term strategy and operations, ordinary course of business capital expenditures and sales of finished product, are made by local management with regular guidance and input from us. ​ For AXT’s minority investment entities that are not consolidated, the investment balances are included in “Other assets” in our condensed consolidated balance sheets and totaled $11.3 million and $10.2 million as of March 31, 2022 and December 31, 2021, respectively. Our respective ownership interests in each of these companies are 46%, 39%, 25%, 25% and 25%. These minority investment entities are not considered variable interest entities because: ​ ● all minority investment entities have sustainable businesses of their own; ​ ● our voting power is proportionate to our ownership interests; ​ ● we only recognize our respective share of the losses and/or residual returns generated by the companies if they occur; and ​ ● we do not have controlling financial interest in, do not maintain operational or management control of, do not control the board of directors of, and are not required to provide additional investment or financial support to any of these companies. ​ In June 2021, we received a $774,000 dividend from one of our equity investments, Xiaoyi XingAn Gallium Co., Ltd. ​ AXT’s minority investment entities are not consolidated and are accounted for under the equity method. Excluding one fully impaired entity, the equity investment entities had the following summarized statements of operations information (in thousands) for the three months ended March 31, 2022 and 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2022 2021 Net revenue ​ $ 10,734 ​ $ 8,525 ​ Gross profit ​ $ 5,999 ​ $ 3,807 ​ Operating income ​ $ 4,149 ​ $ 3,061 ​ Net income ​ $ 3,698 ​ $ 2,612 ​ ​ Our portion of the income and losses from these minority investment entities that are not consolidated and are accounted for under the equity method was income of $1.1 million and $1.1 million, respectively, for the three months ended March 31, 2022 and 2021.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2022
Stockholders' Equity
Stockholders' Equity	Note 8. Stockholders’ Equity ​ Condensed Consolidated Statements of Stockholders’ Equity (in thousands) ​ The changes in stockholders’ equity by component for the three months ended March 31, 2022 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other ​ AXT, Inc. Total ​ ​ Preferred Common Additional Accumulated Comprehensive ​ Stockholders’ Noncontrolling Stockholders’ ​ ​ Stock Stock Paid-In Capital Deficit Income (Loss) Equity Interests Equity Balance as of December 31, 2021 $ 3,532 $ 43 $ 231,622 $ (29,970) $ 6,302 ​ $ 211,529 $ 18,317 $ 229,846 ​ Investment in subsidiary with noncontrolling interest ​ ​ — ​ ​ — ​ ​ (410) ​ ​ — ​ ​ — ​ ​ (410) ​ ​ 204 ​ ​ (206) ​ Noncontrolling interest portion of Tongmei stock-based compensation ​ ​ — ​ ​ — ​ ​ 17 ​ ​ — ​ ​ — ​ ​ 17 ​ ​ (7) ​ ​ 10 ​ Stock-based compensation ​ ​ — ​ ​ — ​ ​ 875 ​ ​ — ​ ​ — ​ ​ 875 ​ ​ — ​ ​ 875 ​ Tongmei stock-based compensation ​ ​ — ​ ​ — ​ ​ 213 ​ ​ — ​ ​ — ​ ​ 213 ​ ​ — ​ ​ 213 ​ Net income ​ ​ — ​ ​ — ​ ​ — ​ ​ 3,165 ​ ​ — ​ ​ 3,165 ​ ​ 389 ​ ​ 3,554 ​ Investment in subsidiary from noncontrolling interest ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 1,887 ​ ​ 1,887 ​ Other comprehensive income ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 327 ​ ​ 327 ​ ​ 45 ​ ​ 372 ​ Balance as of March 31, 2022 $ 3,532 ​ $ 43 ​ $ 232,317 ​ $ (26,805) ​ $ 6,629 ​ $ 215,716 ​ $ 20,835 ​ $ 236,551 ​ ​ Net income and other comprehensive income attributable to redeemable noncontrolling interests was $418,000 and $46,000, respectively, not shown in the table above. The changes in stockholders’ equity by component for the three months ended March 31, 2021 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other ​ AXT, Inc. Total ​ Preferred Common Additional Accumulated Comprehensive ​ Stockholders’ Noncontrolling Stockholders’ ​ Stock Stock Paid-In Capital Deficit Income (Loss) Equity Interests Equity Balance as of December 31, 2020 $ 3,532 $ 42 $ 230,381 $ (44,545) $ 3,209 ​ $ 192,619 $ 15,350 $ 207,969 Common stock options exercised ​ ​ — ​ ​ — ​ ​ 704 ​ ​ — ​ ​ — ​ ​ 704 ​ ​ — ​ ​ 704 Stock-based compensation ​ ​ — ​ ​ — ​ ​ 816 ​ ​ — ​ ​ — ​ ​ 816 ​ ​ — ​ ​ 816 Formation of new subsidiary with noncontrolling interests ​ ​ — ​ ​ — ​ ​ (131) ​ ​ — ​ ​ — ​ ​ (131) ​ ​ 707 ​ ​ 576 Sale of common stock to employees in connection with the reorganization ​ ​ — ​ ​ — ​ ​ 538 ​ ​ — ​ ​ — ​ ​ 538 ​ ​ — ​ ​ 538 Purchase of subsidiary shares from noncontrolling interests ​ ​ — ​ ​ — ​ ​ (2,691) ​ ​ — ​ ​ — ​ ​ (2,691) ​ ​ (1,039) ​ ​ (3,730) Net income (loss) ​ ​ — ​ ​ — ​ ​ — ​ ​ 3,425 ​ ​ — ​ ​ 3,425 ​ ​ 311 ​ ​ 3,736 Other comprehensive loss ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (131) ​ ​ (131) ​ ​ (16) ​ ​ (147) Balance as of March 31, 2021 ​ $ 3,532 ​ $ 42 ​ $ 229,617 ​ $ (41,120) ​ $ 3,078 ​ $ 195,149 ​ $ 15,313 ​ $ 210,462 ​ ​ There were no reclassification adjustments from accumulated other comprehensive income (loss) for . ​ Stock Repurchase Program ​ On October 27, 2014, our Board of Directors approved a stock repurchase program pursuant to which we may repurchase up to $5.0 million of our outstanding common stock. These repurchases can be made from time to time in the open market and are funded from our existing cash balances and cash generated from operations. No shares were repurchased from 2016 through 2021. During the three months ended March 31, 2022, we did no t repurchase any shares under the approved stock repurchase program. As of March 31, 2022, approximately $2.7 million remained available for future repurchases under this program. Currently, we do not plan to repurchase additional shares.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2022
Stock-Based Compensation
Stock-Based Compensation	Note 9. Stock-Based Compensation ​ We account for stock-based compensation in accordance with the provisions of ASC Topic 718, Compensation-Stock Compensation ​ The following table summarizes compensation costs related to our stock-based awards (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ ​ March 31, ​ ​ 2022 2021 Cost of revenue ​ ​ $ 113 ​ $ 39 ​ Selling, general and administrative ​ ​ 811 ​ 640 ​ Research and development ​ ​ 164 ​ 137 ​ Total stock-based compensation ​ ​ 1,088 ​ 816 ​ Tax effect on stock-based compensation ​ ​ — ​ — ​ Net effect on net income ​ ​ $ 1,088 ​ $ 816 ​ ​ As of March 31, 2022, the unamortized compensation costs related to unvested stock options granted to employees under our stock option plan was approximately $0.3 million, net of estimated forfeitures of $35,000 . These costs will be amortized on a straight-line basis over a weighted-average period of will be adjusted for subsequent changes in estimated forfeitures. We any stock-based compensation to inventory as of March 31, 2022 and December 31, 2021 due to the immateriality of the amount. ​ We estimate the fair value of stock options using the Black-Scholes valuation model, consistent with the provisions of ASC 718. There were no options granted in the three months ended March 31, 2022 and 2021. ​ The following table summarizes the stock option transactions during the three months ended March 31, 2022 (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ ​ average ​ ​ ​ ​ ​ ​ Weighted- ​ Remaining ​ ​ ​ ​ ​ Number of ​ average ​ Contractual ​ Aggregate ​ ​ Options ​ Exercise ​ Life ​ Intrinsic Stock Options Outstanding Price (in years) Value Balance as of January 1, 2022 1,378 ​ $ 4.83 5.60 ​ $ 5,573 ​ Granted — ​ — ​ ​ ​ ​ ​ ​ Exercised — ​ ​ — ​ ​ ​ ​ ​ ​ Canceled and expired — ​ ​ — ​ ​ ​ ​ ​ ​ Balance as of March 31, 2022 1,378 ​ $ 4.83 5.36 ​ $ 3,383 ​ Options vested as of March 31, 2022 and unvested options expected to vest, net of forfeitures 1,376 ​ $ 4.83 5.35 ​ $ 3,371 ​ Options exercisable as of March 31, 2022 1,140 ​ $ 5.10 4.92 ​ $ 2,547 ​ ​ The aggregate intrinsic value in the table above represents the total pretax intrinsic value, based on our closing price of $7.02 on March 31, 2022, which would have been received by the option holder had all option holders exercised their options on that date. ​ Restricted stock awards ​ A summary of activity related to restricted stock awards for the three months ended March 31, 2022 is presented below (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ Grant Date Stock Awards Shares Share Value Non-vested as of January 1, 2022 ​ 875 ​ $ 6.26 ​ Granted 2 ​ $ 9.05 ​ Vested (9) ​ $ 11.60 ​ Forfeited ​ (8) ​ $ 5.21 ​ Non-vested as of March 31, 2022 860 ​ $ 6.22 ​ ​ As of March 31, 2022, the unamortized compensation costs related to unvested restricted stock awards was approximately $4.3 million, which is to be amortized on a straight-line basis over a weighted-average period of approximately 1.4 years. ​ At-Risk, Performance Shares ​ In February 2021 and 2022, the Company issued at-risk, performance shares classified as equity awards. Expense is recognized quarterly on a straight-line method over the requisite service period, based on the probability of achieving the specified financial performance metric, with changes in expectations recognized as an adjustment to earnings in the period of change. Compensation cost is not recognized for at-risk, performance shares that do not vest because service or performance conditions are not satisfied and any previously recognized compensation cost is reversed. At-risk, performance shares are eligible to receive dividend equivalents under the Company's 2015 Equity Incentive Plan (the “Plan”), as determined by the Board of Directors. The Company will recognize forfeitures as they occur. ​ The Company's at-risk, performance shares are classified as equity and contain performance and service conditions that must be satisfied for an employee to receive the shares. The financial performance metric for the at-risk, performance shares issued in February 2021 is based upon year-end 2020 actual results as compared to the Company’s year-end actual results in 2021. The financial performance metric for the at-risk, performance shares issued in February 2022 is based upon year-end 2021 actual results as compared to the Company’s year-end actual results in 2022. All performance shares, if earned, are still subject to annual vesting over a four-year period except that no shares are vested on the first anniversary because the performance measurement is based on year-end results for the year 2021 and 2022, respectively. ​ The fair value of the at-risk, performance shares is determined based on the closing price of the Company’s common stock on the first day after the public issuance of the Company’s earnings release for the most recent fiscal quarter, following the Compensation Committee and Board of Directors approval, which is considered the grant date. The fair value per share of the at-risk, performance shares classified as equity awards granted in February 2021 and 2022 was $15.37 and $7.83, respectively. ​ On February 17, 2021, the Compensation Committee recommended, and the Board approved, the grant to Dr. Morris Young, our Chief Executive Officer, of 113,130 at-risk, performance shares under the Plan. On February 17, 2021, the Compensation Committee approved the grant to Gary Fischer, our Chief Financial Officer and Corporate Secretary, of 38,475 at-risk, performance shares under the Plan. On March 14, 2022, the Compensation Committee met and certified that the year-over-year annual revenue growth rate achieved for fiscal year 2021, expressed as a percentage, was 44%. Therefore, all of the at-risk performance shares became eligible to vest. ​ On February 15, 2022, the Compensation Committee recommended, and the Board approved, the grant to Dr. Morris Young of 114,320 at-risk, performance shares under the Plan. On February 15, 2022, the Compensation Committee approved the grant to Gary Fischer of 32,100 at-risk, performance shares under the Plan. If the performance financial metric is less than 50% achieved these shares are forfeited. If the performance financial metric is between 50% and 200% achieved, then a corresponding pro rata portion of the 114,320 shares issued to Dr. Young would be eligible to vest and a corresponding pro rata portion of the 32,100 shares issued to Mr. Fischer would be eligible to vest. Any shares that are not eligible to vest are forfeited. If the target financial metric exceeds 200%, then the maximum number of at-risk performance shares that would be eligible to vest is 114,320 for Dr. Young and 32,100 for Mr. Fischer. ​ A summary of the status of our unvested at-risk, performance shares as of March 31, 2022 is presented below (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ Grant Date Stock Awards Shares* Share Value Non-vested as of January 1, 2022 ​ 114 ​ $ 15.37 Granted 74 ** $ 10.91 Vested — ​ $ — Forfeited ​ — ​ $ — Non-vested as of March 31, 2022 188 ​ $ 12.42 ​ *The number of shares presented is based on achieving 150% of the targeted financial performance metric as defined in the at-risk, performance shares agreement. ​ ** The first annual vesting was reported in Q4 2021, when 25% of the at-risk performance shares became eligible subject to review and confirmation by the Compensation Committee after year-end results were certified. ​ As of March 31, 2022, there was $1.5 million of unrecognized compensation expense related to unvested at-risk, performance shares that is expected to be recognized over a weighted-average period of 1.8 years.

Net Income (Loss) Per Share

Net Income (Loss) Per Share	3 Months Ended
	Mar. 31, 2022
Net Income (Loss) Per Share
Net Income (Loss) Per Share	Note 10. Net Income (Loss) Per Share ​ Basic net income (loss) per share is computed using the weighted-average number of common shares outstanding during the periods less shares of common stock subject to repurchase and non-vested stock awards. Diluted net income (loss) per share is computed using the weighted-average number of common shares outstanding and potentially dilutive common shares outstanding during the periods. The dilutive effect of outstanding stock options and restricted stock awards is reflected in diluted earnings per share by application of the treasury stock method. Potentially dilutive common shares consist of common shares issuable upon the exercise of stock options and vesting of restricted stock awards. Potentially dilutive common shares are excluded from the computation of weighted-average number of common shares outstanding in net loss years, as their effect would be anti-dilutive to the computation. ​ A reconciliation of the numerators and denominators of the basic and diluted net income (loss) per share calculations is as follows (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ ​ March 31, ​ ​ 2022 2021 Numerator: ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to AXT, Inc. ​ ​ $ 3,165 ​ $ 3,425 ​ Less: Preferred stock dividends ​ ​ (44) ​ (44) ​ Net income available to common stockholders ​ ​ $ 3,121 ​ $ 3,381 ​ Denominator: ​ ​ ​ ​ ​ ​ ​ ​ Denominator for basic net income per share - weighted-average common shares ​ ​ 41,871 ​ 41,004 ​ Effect of dilutive securities: ​ ​ ​ ​ ​ ​ ​ ​ Common stock options ​ ​ 474 ​ 1,082 ​ Restricted stock awards ​ ​ 317 ​ 640 ​ Denominator for dilutive net income per common shares ​ ​ 42,662 ​ 42,726 ​ Net income attributable to AXT, Inc. per common share: ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ ​ $ 0.07 ​ $ 0.08 ​ Diluted ​ ​ $ 0.07 ​ $ 0.08 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options excluded from diluted net income (loss) per share as the impact is anti-dilutive ​ ​ 201 ​ 21 ​ Restricted stock excluded from diluted net income (loss) per share as the impact is anti-dilutive ​ ​ 218 ​ 57 ​ ​ The 883,000 shares of $0.001 par value Series A preferred stock issued and outstanding as of March 31, 2022 and December 31, 2021, valued at $3,532,000, are non-voting and non-convertible preferred stock with a 5.0% cumulative annual dividend rate payable when declared by the Board of Directors and a $4 per share liquidation preference over common stock, which must be paid before any distribution is made to common stockholders. These preferred shares were issued to Lyte Optronics, Inc. stockholders in connection with the completion of our acquisition of Lyte Optronics, Inc. on May 28, 1999.

Segment Information and Foreign

Segment Information and Foreign Operations	3 Months Ended
	Mar. 31, 2022
Segment Information and Foreign Operations
Segment Information and Foreign Operations	Note 11. Segment Information and Foreign Operations ​ Segment Information ​ We operate in one segment for the design, development, manufacture and distribution of high-performance compound and single element semiconductor substrates and sale of raw materials integral to these substrates. Our chief operating decision-maker has been identified as our Chief Executive Officer, who reviews operating results to make decisions about allocating resources and assessing performance for the Company. Since we operate in one segment, all financial segment and product line information can be found in the condensed consolidated financial statements. ​ Product Information ​ The following table represents revenue amounts (in thousands) by product type: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ ​ March 31, ​ ​ ​ 2022 2021 Product Type: ​ ​ ​ ​ ​ ​ ​ ​ Substrates ​ $ 31,745 ​ $ 23,373 ​ ​ Raw Materials and Other ​ 7,908 ​ 7,977 ​ ​ Total ​ $ 39,653 ​ $ 31,350 ​ ​ ​ Geographical Information ​ The following table represents revenue amounts (in thousands) reported for products shipped to customers in the corresponding geographic region: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ ​ March 31, ​ ​ ​ 2022 2021 Geographical region: ​ ​ ​ ​ ​ ​ ​ ​ China ​ $ 17,480 ​ $ 15,546 ​ ​ Taiwan ​ ​ 6,859 ​ ​ 3,015 ​ ​ Japan ​ 2,807 ​ 2,523 ​ ​ Asia Pacific (excluding China, Taiwan and Japan) ​ ​ 1,756 ​ ​ 1,817 ​ ​ Europe (primarily Germany) ​ ​ 6,394 ​ ​ 5,435 ​ ​ North America (primarily the United States) ​ 4,357 ​ 3,014 ​ ​ Total ​ $ 39,653 ​ $ 31,350 ​ ​ ​ Long-lived assets consist primarily of property, plant and equipment and operating lease right-of-use assets, and are attributed to the geographic location in which they are located. Long-lived assets, net of depreciation, by geographic region were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of ​ ​ ​ March 31, ​ December 31, ​ ​ 2022 2021 Long-lived assets by geographic region, net of depreciation: ​ ​ ​ ​ ​ ​ ​ North America ​ $ 897 ​ $ 1,610 ​ China ​ 148,612 ​ 143,129 ​ ​ ​ $ 149,509 ​ $ 144,739 ​ ​ Significant Customers ​ One customer, Landmark, represented 10% of our revenue for the three months ended March 31, ​ We perform ongoing credit evaluations of our customers’ financial condition, and limit the amount of credit extended when deemed necessary, but generally do not require collateral. Two customers accounted for 12% and 10% of our accounts receivable balance as of March 31, 2022 ,

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2022
Commitments and Contingencies
Commitments and Contingencies	Note 12. Commitments and Contingencies ​ Indemnification Agreements ​ We have entered into indemnification agreements with our directors and officers that require us to indemnify our directors and officers against liabilities that may arise by reason of their status or service as directors or officers, other than liabilities arising from willful misconduct of a culpable nature; to advance their expenses incurred as a result of any proceeding against them as to which they could be indemnified; and to obtain directors’ and officers’ insurance if available on reasonable terms, which we currently have in place. ​ Product Warranty ​ We provide warranties for our products for a specific period of time, generally twelve months, against material defects. We provide for the estimated future costs of warranty obligations in cost of sales when the related revenue is recognized. The accrued warranty costs represent the best estimate at the time of sale of the total costs that we expect to incur to repair or replace product parts that fail while still under warranty. The amount of accrued estimated warranty costs is primarily based on historical experience as to product failures as well as current information on repair costs. On a quarterly basis, we review the accrued balances and update the historical warranty cost trends. ​ The following table reflects the change in our warranty accrual which is included in “Accrued liabilities” in the condensed consolidated balance sheets, during the three months ended March 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2022 2021 Beginning accrued product warranty ​ $ 743 ​ $ 609 ​ Accruals for warranties issued ​ 556 ​ 113 ​ Adjustments related to pre-existing warranties including expirations and changes in estimates ​ (113) ​ (54) ​ Cost of warranty repair ​ (354) ​ (86) ​ Ending accrued product warranty ​ $ 832 ​ $ 582 ​ ​ Contractual Obligations ​ In 2020, we and a competitor entered into a cross license and covenant agreement (the “Cross License Agreement”), which has a term that began on January 1, 2020 and expires on December 31, 2029. The Cross License Agreement is a fixed-cost cross license and not a variable-cost cross license that is based on revenue or units. Under the Cross License Agreement, we are obligated to make annual payments over a ​ Land Purchase and Investment Agreement ​ We have established a wafer process production line in Dingxing, China. In addition to a land rights and building purchase agreement that we entered into with a private real estate development company to acquire our new manufacturing facility, we also entered into a cooperation agreement with the Dingxing local government. In addition to pledging its full support and cooperation, the Dingxing local government will issue certain credits or rebates to us as we achieve certain milestones. We, in turn, agreed to hire local workers over time, pay taxes when due and eventually demonstrate a total investment of approximately $90 million in value, assets and capital. The investment will include cash paid for the land and buildings, cash on deposit in our name at local banks, the gross value of new and used equipment (including future equipment that might be used for indium phosphide and germanium substrates production), the deemed value for our customer list or the end user of our substrates, for example, the end users of 3-D sensing VCSELs (vertical cavity surface emitting lasers), a deemed value for employment of local citizens, a deemed value for our proprietary process technology, other intellectual property, other intangibles and additional items of value. There is no timeline or deadline by which this must be accomplished, rather it is a good faith covenant entered into between AXT and the Dingxing local government. Further, there is no specific penalty contemplated if either party breaches the agreement. However, the agreement does state that each party has a right to seek from the other party compensation for losses. Under certain conditions, the Dingxing local government may purchase the land and building at the appraised value. We believe that such cooperation agreements are normal, customary and usual in China and that the future valuation is flexible. We have a similar agreement with the city of Kazuo, China, although on a smaller scale. The total investment targeted by AXT in Kazuo is approximately $15 million in value, assets and capital. In addition, BoYu has a similar agreement with the city of Kazuo. The total investment targeted by BoYu in Kazuo is approximately $8 million in value, assets and capital. ​ Purchase Obligations with Penalties for Cancellation ​ In the normal course of business, we issue purchase orders to various suppliers. In certain cases, we may incur a penalty if we cancel the purchase order. As of March 31, 2022, we do not have any outstanding purchase orders that will incur a penalty if cancelled by the Company. ​ Legal Proceedings ​ From time to time we may be involved in judicial or administrative proceedings concerning matters arising in the ordinary course of business. We do not expect that any of these matters, individually or in the aggregate, will have a material adverse effect on our business, financial condition, cash flows or results of operations.

Other Expense, Net

Other Expense, Net	3 Months Ended
	Mar. 31, 2022
Other Expense, Net
Other Expense, Net	Note 13. Other Expense, Net ​ Other expense, net for the three months ended March 31, 2022 and 2021, includes a grant of $0.2 million and $0.1 million, respectively, from a Chinese provincial government agency as an award for relocating to its province. ​ In addition, we incurred a foreign currency transaction exchange loss of $228,000 and $173,000 for the three months ended March 31, 2022 and 2021, respectively.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2022
Income Taxes
Income Taxes	Note 14. Income Taxes ​ We account for income taxes in accordance with ASC Topic 740, Income Taxes between the book and tax bases of recorded assets and liabilities. ASC 740 also requires that deferred tax assets be reduced by a valuation allowance if it is more likely than not that a portion of the deferred tax asset will not be realized. ​ We provide for income taxes based upon the geographic composition of worldwide earnings and tax regulations governing each region, particularly China. The calculation of tax liabilities involves significant judgment in estimating the impact of uncertainties in the application of complex tax laws, particularly in foreign countries such as China. ​ We recognize interest and penalties related to uncertain tax positions in income tax expense. Income tax expense for the three months ended March 31, 2022 includes no interest and penalties. As of March 31, 2022, we have no accrued interest and penalties related to uncertain tax positions. We file income tax returns in the U.S. federal, various states and foreign jurisdictions. Currently, there is no tax audit in any of the jurisdictions and we do not expect there will be any significant change to this. Provision for income taxes for the three months ended March 31, 2022 was mostly related to our wholly owned China subsidiaries and our partially owned subsidiaries in China. Income taxes and certain state taxes, have been provided for our U.S. operations as most of the income in the U.S. had been fully offset by utilization of federal and state net operating loss carryforwards except for the newly created US subsidiary, AXT-Tongmei. Which has incurred tax expense. ​ Under the 2017 Tax Cuts and Jobs Act (TCJA), research and experimental (“R&E”), expenditures incurred or paid for tax years beginning after December 31, 2021, will no longer be immediately deductible for tax purposes. Instead, businesses are now required to capitalize and amortize R&E expenditures over a period of five years for research conducted within the U.S. or 15 years for research conducted in a foreign jurisdiction. We capitalize the R&E expense for our US Corporation and amortize it over 5 years. We also capitalize the R&E expense in our China subsidiaries and amortize it over 15 years. ​ On June 29, 2020, California Governor Gavin Newsom signed Assembly Bill 85 (“AB 85”) into law as part of the California 2020 Budget Act, which temporarily suspends the use of California net operating losses and imposes a cap on the amount of business incentive tax credits that companies can utilize against their net income for tax years 2020, 2021, and 2022. We analyzed the provisions of AB 85 and determined there was no impact on our provision for income taxes for the current period and will continue to evaluate the impact, if any, AB 85 may have on the Company’s condensed consolidated financial statements and disclosures .

Revenue

Revenue	3 Months Ended
	Mar. 31, 2022
Revenue
Revenue	Note 15. Revenue ​ Revenue Recognition ​ We manufacture and sell high-performance compound semiconductor substrates including indium phosphide, gallium arsenide and germanium wafers, and our consolidated subsidiaries sell certain raw materials, including high purity gallium (7N Ga), pyrolytic boron nitride (pBN) crucibles and boron oxide (B2O3). After we ship our products, there are no remaining obligations or customer acceptance requirements that would preclude revenue recognition. Our products are typically sold pursuant to purchase orders placed by our customers, and our terms and conditions of sale do not require customer acceptance. We account for a contract with a customer when there is a legally enforceable contract, which could be the customer’s purchase order, the rights of the parties are identified, the contract has commercial terms, and collectibility of the contract consideration is probable. The majority of our contracts have a single performance obligation to transfer products and are short term in nature, usually less than six months. Our revenue is measured based on the consideration specified in the contract with each customer in exchange for transferring products that are generally based upon a negotiated, formula, list or fixed price. Revenue is recognized when control of the promised goods is transferred to our customer, which is either upon shipment from our dock, receipt at the customer’s dock, or removal from consignment inventory at the customer’s location, in an amount that reflects the consideration we expect to be entitled to receive in exchange for those goods. ​ We have elected to account for shipping and handling as activities to fulfill the promise to transfer the goods. Shipping and handling fees billed to customers in a sales transaction are recorded as an offset to shipping and handling expenses. Sales taxes and value added taxes in foreign jurisdictions that are collected from customers and remitted to governmental authorities are accounted for on a net basis and, therefore, are excluded from revenue. ​ We do not provide training, installation or commissioning services. We provide for future returns based on historical data, prior experience, current economic trends and changes in customer demand at the time revenue is recognized. We do not recognize any asset associated with the incremental cost of obtaining revenue generating customer contracts. As such, sales commissions are expensed as incurred, given that the expected period of benefit is less than one year. ​ Contract Balances ​ Contract assets are recorded when we have a conditional right to consideration for our completed performance under the contracts. Accounts receivables are recorded when the right to this consideration becomes unconditional. We believe the fair value of our accounts receivable approximates its carrying value due to its short maturities and nominal credit risk. We do not have any material contract assets as of March 31, 2022. In some contracts we require payment in advance of shipment, per a billing schedule reflected in our customer contracts, and the payment is recorded as a contract liability. The following table reflects the contract liabilities balance, which is included in “Accrued liabilities” on the condensed consolidated balance sheets, as of March 31, 2022 and December 31, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ ​ ​ 2022 ​ 2021 ​ Contract liabilities ​ $ 1,024 ​ $ 946 ​ During the three months ended March 31, 2022, the Company recognized $321,000 of revenue that was included in the contract balances as of December 31, 2021. ​ ​ ​ ​ ​ ​ ​ Disaggregated Revenue ​ In general, revenue disaggregated by product types and geography (See Note 11) is aligned according to the nature and economic characteristics of our business and provides meaningful disaggregation of our results of operations. Since we operate in one segment, all financial segment and product line information can be found in the condensed consolidated financial statements.

Bank Loans and Line of Credit

Bank Loans and Line of Credit	3 Months Ended
	Mar. 31, 2022
Bank Loans and Line of Credit
Bank Loans and Line of Credit	Note 16. Bank Loans and Line of Credit ​ On August 9, 2019, Tongmei entered into a credit facility (the “Credit Facility”) with the Bank of China with a $5.8 million line of credit at an annual interest rate of approximately 0.4% over the average interest rate quoted by the National Interbank Funding Center. Accrued interest is calculated monthly and paid quarterly. The annual interest rate was approximately 4.7% as of December 31, 2019. The Credit Facility is collateralized by Baoding Tongmei’s land use rights and all of its buildings located at its facility in Dingxing. The primary intended use of the Credit Facility is for general purposes, which may include working capital and other corporate expenses. ​ On August 9, 2019, Tongmei borrowed $2.8 million against the Credit Facility (the “August 2019 borrowing”). The repayment of the full amount was due on August 9, 2020. On September 12, 2019, we borrowed an additional $2.8 million against the Credit Facility (the “September 2019 borrowing”). The repayment of the full amount was due on September 12, 2020. In August 2020, Tongmei repaid the full amount of the Credit Facility, including all outstanding accrued interest, of approximately $5.9 million and simultaneously applied to renew the Credit Facility. The process of repaying a loan and then renewing the loan is customary in China. ​ In September 2020, the August 2019 borrowing was renewed and funded against the Credit Facility with an interest rate of 3.85%. The interest owed during the term of the loan was deducted prior to funding. The repayment of the loan was due on March 22, 2021, however the Credit Facility contains an option to renew for an additional six months, which was exercised in March 2021 for approximately $3.1 million. In September 2021, Tongmei repaid $3.1 million of the Credit Facility, including all outstanding accrued interest and simultaneously applied to renew the Credit Facility. In September 2021, the Credit Facility was renewed for approximately $2.7 million with an annual interest rate of 3.85%. In March 2022, Tongmei repaid $2.7 million of the Credit Facility, including all outstanding accrued interest. As of March 31, 2022, $0 was included in “Bank loan” in our condensed consolidated balance sheets. ​ In October 2020, the September 2019 borrowing was renewed and funded against the Credit Facility and an additional $2.7 million was approved and funded against the Credit Facility with the annual interest rate of 4.7 %. Accrued interest is calculated monthly and paid quarterly. The combined loan totaled $5.6 ​ In February 2020, our consolidated subsidiary, BoYu, entered into a credit facility with the Industrial and Commercial Bank of China (“ICBC”) with a $1.4 million line of credit at an annual interest rate of approximately 0.15% over the loan prime rate. Accrued interest is calculated monthly and paid quarterly. The annual interest rate was approximately 4.3% as of December 31, 2020. The credit facility is collateralized by BoYu’s land use rights and its building located at its facility in Tianjin, China and BoYu’s accounts receivable. The primary intended use of the credit facility is for general purposes, which may include working capital and other corporate expenses. ​ % as of December 31, 2021. As of March 31, 2022, $1.6 million was included in “Bank loan” in our condensed consolidated balance sheets. ​ ​ In December 2021, Tongmei entered into a credit facility with China Merchants Bank for $1.6 million with an annual interest rate of 3.55%. Accrued interest is calculated monthly and paid quarterly. The repayment of the loan and any accrued interest is due on December 6, 2022. The loan is guaranteed by Beijing Capital Financing Guarantee Co., Ltd. In exchange for the guarantee, Tongmei paid Beijing Capital Financing Guarantee Co., Ltd. a fee of 1.5% of the loan amount or approximately $24,000. As of March 31, 2022, $1.6 million was included in “Bank loan” in our condensed consolidated balance sheets. ​ ​ In January 2022, ChaoYang Tongmei entered into a credit facility with the Bank of Communications for $1.6 million with an annual interest rate of 3.3%. The interest owed during the term of the loan was deducted prior to funding. The repayment of the loan is due in January 2023. As of March 31, 2022, $1.6 million was included in “Bank loan” in our condensed consolidated balance sheets. ​ In January 2022, ChaoYang JinMei entered into a credit facility with the Bank of Communications for $1.6 million with an annual interest rate of 3.3 %. The interest owed during the term of the loan was deducted prior to funding. The repayment of the loan is due in January 2023. As of March 31, 2022, $1.6 million was included in “Bank loan” in our condensed consolidated balance sheets. ​ In January 2022, Tongmei entered into a credit facility with the Bank of China for $4.4 million with an annual interest rate of 4.55%. Accrued interest is calculated monthly and paid quarterly. The repayment of the loan and any accrued interest is due in January 2023. The Credit Facility is collateralized by Baoding Tongmei Xtal Technology Co., Ltd.’s land use rights and all of its buildings located at its facility in Dingxing, China. As of March 31, 2022, $4.4 million was included in “Bank loan” in our condensed consolidated balance sheets. ​ In March 2022, Tongmei entered into a credit facility with the Bank of China for $3.1 million with an annual interest rate of 3.7%. The interest owed during the term of the loan was deducted prior to funding. The repayment of the loan is due in September 2022. As of March 31, 2022, $3.1 million was included in “Bank loan” in our condensed consolidated balance sheets. ​ ​

Leases

Leases	3 Months Ended
	Mar. 31, 2022
Leases
Leases	Note 17. Leases ​ We lease certain equipment, office space, warehouse and facilities under long-term operating leases expiring at various dates through July 2029. The majority of our lease obligations relate to our lease agreement for a nitrogen system to be used during the manufacturing process for our facility in Dingxing, China. The equipment lease became effective in August 2019 and will expire in July 2029. There are no variable lease payments, residual value guarantees or any restrictions or covenants imposed by the equipment lease. The remainder relate to our lease agreement for our facility in Fremont, California with approximately 19,467 square feet, which was scheduled to expire in 2020. Under the terms of the facility lease agreement, in May 2020, we were granted an extension to the term of the lease for an additional three years. There are no variable lease ​ Leases are classified as either finance leases or operating leases. A lease is classified as a finance lease if any one of the following criteria are met: the lease transfers ownership of the asset by the end of the lease term, the lease contains an option to purchase the asset that is reasonably certain to be exercised, the lease term is for a major part of the remaining useful life of the asset or the present value of the lease payments equals or exceeds substantially all of the fair value of the asset. A lease is classified as an operating lease if it does not meet any one of these criteria. All of our leases are classified as operating leases and substantially all of our operating leases are comprised of equipment and office space leases. None of our leases are classified as finance leases. ​ For all leases at the lease commencement date, a right-of-use asset and a lease liability are recognized. The right-of-use asset represents the right to use the leased asset for the lease term. The lease liability represents the present value of the lease payments under the lease. ​ The right-of-use asset is initially measured at cost, which primarily comprises the initial amount of the lease liability, plus any initial direct costs incurred, consisting mainly of brokerage commissions, less any lease incentives received. All right-of-use assets are reviewed for impairment. The lease liability is initially measured at the present value of the lease payments, discounted using the interest rate implicit in the lease or, if that rate cannot be readily determined, our secured incremental borrowing rate for the same term as the underlying lease. ​ Lease payments included in the measurement of the lease liability comprise the following: the fixed noncancelable lease payments, payments for optional renewal periods where it is reasonably certain the renewal period will be exercised, and payments for early termination options unless it is reasonably certain the lease will not be terminated early. ​ Lease expense for operating leases consists of the lease payments plus any initial direct costs, primarily brokerage commissions, and is recognized on a straight-line basis over the lease term. ​ We have elected not to recognize right-of-use assets and lease liabilities for short-term leases that have a term of 12 months or less. The effect of short-term leases on our right-of-use asset and lease liability was not material. ​ As of March 31, 2022, the maturities of our operating lease liabilities (excluding short-term leases) are as follows (in thousands): ​ ​ ​ ​ Maturity of Lease Liabilities ​ 2022 $ 444 2023 ​ 582 2024 ​ 293 2025 ​ 293 2026 ​ 293 Thereafter ​ 757 Total minimum lease payments ​ 2,662 Less: Interest ​ (353) Present value of lease obligations ​ 2,309 Less: Current portion, included in accrued liabilities ​ (499) Long-term portion of lease obligations $ 1,810 ​ The weighted-average remaining lease term and the weighted-average discount rate for our operating leases as of each date is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ ​ ​ 2022 ​ 2021 ​ Weighted-average remaining lease term (years) ​ 6.29 ​ 6.44 ​ Weighted-average discount rate ​ 4.61 % 4.61 % ​ ​ Supplemental cash flow information related to leases where we are the lessee is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ ​ 2022 ​ 2021 ​ Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ 147 ​ $ 141 ​ ​ The components of lease expense are as follows (in thousands) within our condensed consolidated statements of operations: ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, ​ ​ 2022 ​ 2021 Operating lease ​ $ 134 ​ $ 133 Short-term lease expense ​ ​ 36 ​ ​ 24 Total ​ $ 170 ​ $ 157 ​

Redeemable Noncontrolling Inter

Redeemable Noncontrolling Interests	3 Months Ended
	Mar. 31, 2022
Redeemable Noncontrolling Interests
Redeemable Noncontrolling Interests	Note 18. Redeemable Noncontrolling Interests As discussed in Note 1, during the quarter ended December 31, 2020, Tongmei entered into the Capital Investment Agreements with Investors that invested approximately $48.1 million in the form of redeemable noncontrolling interests representing 7.06% of the outstanding shares of Tongmei. An additional investment of approximately $1.5 million of new capital was funded in early January 2021. Under China regulations these investments must be formally approved by the appropriate government agency and are not deemed to be dilutive until such approval is granted. The government approved the entire approximately $49 million investment on January 25, 2021, at which time the Investors owned a redeemable noncontrolling interest in Tongmei of 7.28%. The initial carrying amount of the redeemable noncontrolling interest was recorded at fair value on the date of issuance of Tongmei’s common stock, net of issuance costs and presented in temporary equity on the condensed consolidated balance sheets. This classification is due to the existence of certain contingencies that could result in potential redemption at the fixed purchase price as described below. We currently do not believe that this is probable thus no amortization of the issuance costs has been recorded. Pursuant to the Capital Investment Agreements with the Investors, each Investor has the right to require AXT to redeem any or all Tongmei shares held by such Investor at the original purchase price paid by such Investor, without interest, in the event of a material adverse change or if Tongmei does not achieve its IPO on or before December 31, 2022. The aggregate redemption amount is approximately $49 million. This right is suspended when Tongmei submits its formal application to the Chinese Securities Regulatory Commission (“CSRC”). Tongmei submitted to the Shanghai Stock Exchange the application in December 2021 and it was formally accepted for review on January 10, 2022. The Shanghai Stock Exchange provided comments to the formal application in March 2022 and Tongmei filed an amended application to address the comments on April 14, 2022. The Shanghai Stock Exchange accepted for review the amended application on April 18, 2022 and provided comments to the amended application on April 26, 2022. The Shanghai Stock Exchange has not yet approved the formal application. If the Shanghai Stock Exchange approves the formal application, then the Shanghai Stock Exchange will forward it to the CSRC for further review. The process of going public on the STAR Market includes several periods of review and is therefore a lengthy process. Tongmei does not expect to complete the IPO until the second half of 2022. If, on December 31, 2022, the IPO application remains under review, then the date when such Investor is entitled to exercise such redemption right shall be deferred to a date when such submission is rejected by the CSRC or stock exchange, or the date when Tongmei withdraws its IPO application. If the application is approved and Tongmei completes an IPO the redemption right is cancelled. The listing of Tongmei on the STAR Market will not change the status of AXT as a U.S. public company. ​ The components of the change in redeemable noncontrolling interests for the three months ended March 31, 2022 are presented in the following table (in thousands): ​ ​ ​ Balance as of January 1, 2022 $ 50,385 Investment in subsidiary with redeemable noncontrolling interest ​ 206 Equity issuance costs incurred ​ (227) Stock-based compensation attributable to redeemable noncontrolling interests ​ (6) Net income attributable to redeemable noncontrolling interests ​ 418 Effect of foreign currency translation on redeemable noncontrolling interests ​ 149 Effect of foreign currency translation attributable to redeemable noncontrolling interests ​ 46 Balance as of March 31, 2022 $ 50,971 ​

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2022
Recent Accounting Pronouncements
Recent Accounting Pronouncements	​ Note 19. Recent Accounting Pronouncements ​ In November 2021, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2021-10, Government Assistance (Topic 832): Disclosures by Business Entities about Government Assistance. ASU 2021-10 aims to provide increased transparency by requiring business entities to disclose information about certain types of government assistance they receive in the notes to the financial statements. The FASB broadly defined “government assistance” in ASC 832 to ensure that assistance received from most types of governmental entities or other related organizations would be disclosed. Government assistance within the scope of ASC 832 includes assistance that is administered by domestic, foreign, local (such as city, town, county, or municipality), regional (such as state, provincial, or territorial), national (federal) governments, as well as entities related to those governments (such as departments, independent agencies, boards, commissions, or component units). ASC 832 also includes government assistance from intergovernmental organizations (for example, global organizations such as the United Nations, regional organizations such as the European Union, and economic organizations such as the World Trade Organization). The guidance is effective for fiscal years beginning after December 15, 2021, with early application permitted. Adoption of the new standard had a de minimis effect on our condensed consolidated financial statements. ​ ​

Subsequent Event

Subsequent Event	3 Months Ended
	Mar. 31, 2022
Subsequent Event.
Subsequent Event	Note 20. Subsequent Event ​ In April 2022, Tongmei entered into a capital increase agreement with noncontrolling interests to further invest $4.5 million in our consolidated subsidiary, ChaoYang XinMei. Tongmei’s portion of the investment was approximately $2.6 million, of which $1.1 million was paid in April 2022. Noncontrolling interests’ portion of the investment was approximately $1.9 million, of which $0.7 million was paid in April 2022. As a result, noncontrolling interests increased $0.8 million and redeemable noncontrolling interests increased $0.1 million. Tongmei’s ownership remained at 58.5% after the April 2022 equity investment.

Investments and Fair Value Me_2

Investments and Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2022
Investments and Fair Value Measurements
Cash, cash equivalents and investments	As of March 31, 2022 and December 31, 2021, our cash, cash equivalents and debt investments are classified as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2022 ​ December 31, 2021 ​ ​ ​ Gross Gross ​ ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Cost Gain (Loss) Value Cost Gain (Loss) Value Classified as: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash ​ $ 29,494 ​ $ — ​ $ — ​ $ 29,494 ​ $ 36,763 ​ $ — ​ $ — ​ $ 36,763 ​ Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit 1 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Total cash and cash equivalents ​ 29,494 ​ — ​ — ​ 29,494 ​ 36,763 ​ — ​ — ​ 36,763 ​ Investments (available-for-sale): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit 2 ​ 6,680 ​ — ​ ​ (90) ​ 6,590 ​ 6,680 ​ — ​ ​ (19) ​ 6,661 ​ Corporate bonds ​ 8,357 ​ — ​ (147) ​ 8,210 ​ 8,380 ​ — ​ (46) ​ 8,334 ​ Total investments ​ 15,037 ​ — ​ (237) ​ 14,800 ​ 15,060 ​ — ​ (65) ​ 14,995 ​ Total cash, cash equivalents and investments ​ $ 44,531 ​ $ — ​ $ (237) ​ $ 44,294 ​ $ 51,823 ​ $ — ​ $ (65) ​ $ 51,758 ​ Contractual maturities on investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Due within 1 year 3 ​ $ 5,409 ​ ​ ​ ​ ​ ​ ​ $ 5,400 ​ $ 5,424 ​ ​ ​ ​ ​ ​ ​ $ 5,419 ​ Due after 1 through 5 years 4 ​ 9,627 ​ ​ ​ ​ ​ ​ ​ 9,400 ​ 9,636 ​ ​ ​ ​ ​ ​ ​ 9,576 ​ ​ ​ $ 15,036 ​ ​ ​ ​ ​ ​ ​ $ 14,800 ​ $ 15,060 ​ ​ ​ ​ ​ ​ ​ $ 14,995 ​ 1. Certificates of deposit with original maturities of less than three months. 2. Certificates of deposit with original maturities of more than three months. 3. Classified as “Short-term investments” in our condensed consolidated balance sheets. 4. Classified as “Long-term investments” in our condensed consolidated balance sheets.
Fair value and gross unrealized losses related to available-for-sale securities	The following table summarizes the fair value and gross unrealized losses related to available-for-sale debt securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of March 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ In Loss Position ​ In Loss Position ​ Total In ​ ​ < 12 months ​ > 12 months ​ Loss Position ​ ​ ​ ​ ​ Gross ​ ​ ​ ​ Gross ​ ​ ​ ​ Gross ​ ​ Fair ​ Unrealized ​ Fair ​ Unrealized ​ Fair ​ Unrealized As of March 31, 2022 Value (Losses) Value (Losses) Value (Losses) Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ $ 6,590 ​ $ (90) ​ $ — ​ $ — ​ $ 6,590 ​ $ (90) ​ Corporate bonds ​ 4,857 ​ (139) ​ 3,002 ​ (7) ​ 7,859 ​ ​ (146) ​ Total in loss position ​ $ 11,447 ​ $ (229) ​ $ 3,002 ​ $ (7) ​ $ 14,449 ​ $ (236) ​ ​ ​ The following table summarizes the fair value and gross unrealized losses related to available-for-sale debt securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ In Loss Position ​ In Loss Position ​ Total In ​ ​ < 12 months ​ > 12 months ​ Loss Position ​ ​ Gross ​ Gross ​ Gross ​ ​ Fair ​ Unrealized ​ Fair ​ Unrealized ​ Fair ​ Unrealized As of December 31, 2021 ​ Value ​ (Loss) ​ Value ​ (Loss) ​ Value ​ (Loss) Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ $ 6,181 ​ $ (19) ​ $ — ​ $ — ​ $ 6,181 ​ $ (19) ​ Corporate bonds ​ 5,970 ​ (42) ​ 2,013 ​ (4) ​ 7,983 ​ ​ (46) ​ Total in loss position ​ $ 12,151 ​ $ (61) ​ $ 2,013 ​ $ (4) ​ $ 14,164 ​ $ (65) ​
Summary of financial assets and liabilities measured at fair value on a recurring basis	The following table summarizes our financial assets and liabilities measured at fair value on a recurring basis in accordance with ASC 820 as of Mach 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices in ​ ​ ​ Significant ​ ​ ​ ​ ​ Active Markets of ​ Significant Other ​ Unobservable ​ ​ Balance as of ​ Identical Assets ​ Observable Inputs ​ Inputs ​ March 31, 2022 (Level 1) (Level 2) (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents and investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ $ 6,590 ​ $ — ​ $ 6,590 ​ $ — ​ Corporate bonds ​ 8,210 ​ — ​ 8,210 ​ — ​ Total ​ $ 14,800 ​ $ — ​ $ 14,800 ​ $ — ​ ​ The following table summarizes our financial assets and liabilities measured at fair value on a recurring basis in accordance with ASC 820 as of December 31, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices in ​ ​ ​ Significant ​ ​ ​ ​ ​ Active Markets of ​ Significant Other ​ Unobservable ​ ​ Balance as of ​ Identical Assets ​ Observable Inputs ​ Inputs ​ December 31, 2021 (Level 1) (Level 2) (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents and investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ $ 6,661 ​ $ — ​ $ 6,661 ​ $ — ​ Corporate bonds ​ 8,334 ​ — ​ 8,334 ​ — ​ Total ​ $ 14,995 ​ $ — ​ $ 14,995 ​ $ — ​ ​

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2022
Inventories
Components of inventories	The components of inventories are summarized below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ ​ 2022 2021 Inventories: ​ ​ ​ ​ ​ ​ ​ Raw materials ​ $ 32,949 ​ $ 29,658 ​ Work in process ​ 32,411 ​ 32,605 ​ Finished goods ​ 3,461 ​ 3,649 ​ ​ ​ $ 68,821 ​ $ 65,912 ​

Property, Plant and Equipment_2

Property, Plant and Equipment, Net (Tables)	3 Months Ended
	Mar. 31, 2022
Property, Plant and Equipment, Net
Schedule of components of property, plant and equipment	The components of our property, plant and equipment are summarized below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ ​ ​ 2022 ​ 2021 ​ Property, plant and equipment: ​ ​ ​ ​ ​ ​ ​ Machinery and equipment, at cost ​ $ 59,617 ​ $ 59,284 ​ Less: accumulated depreciation and amortization ​ ​ (40,848) ​ ​ (40,292) ​ Building, at cost ​ ​ 109,071 ​ ​ 108,782 ​ Less: accumulated depreciation and amortization ​ ​ (19,560) ​ ​ (18,710) ​ Leasehold improvements, at cost ​ 7,060 ​ 7,039 ​ Less: accumulated depreciation and amortization ​ ​ (5,521) ​ ​ (5,352) ​ Construction in progress ​ 37,467 ​ 31,664 ​ ​ ​ $ 147,286 ​ $ 142,415 ​

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	3 Months Ended
	Mar. 31, 2022
Accrued Liabilities
Schedule of components of accrued liabilities	The components of accrued liabilities are summarized below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ ​ 2022 2021 Accrued compensation and related charges ​ $ 3,436 ​ $ 5,115 ​ Preferred stock dividends payable ​ ​ 2,901 ​ ​ 2,901 ​ Advances from customers ​ ​ 1,024 ​ ​ 946 ​ Accrued income taxes ​ ​ 1,001 ​ ​ 539 ​ Accrued product warranty ​ ​ 832 ​ ​ 743 ​ Current portion of operating lease liabilities ​ ​ 499 ​ ​ 488 ​ Accrued professional services ​ ​ 423 ​ ​ 880 ​ Other personnel-related costs ​ ​ 278 ​ ​ 279 ​ Payable in connection with construction in progress ​ ​ 268 ​ ​ 2,974 ​ Other tax payable ​ ​ 230 ​ ​ 392 ​ Accrual for sales returns ​ ​ 20 ​ ​ 48 ​ Other accrued liabilities ​ ​ 1,301 ​ ​ 1,752 ​ ​ ​ $ 12,213 ​ $ 17,057 ​

Investments in Privately-Held_2

Investments in Privately-Held Raw Material Companies (Tables)	3 Months Ended
	Mar. 31, 2022
Investments in Privately-Held Raw Material Companies
Summary of investments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Investment Balance as of ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ Accounting ​ Ownership * Company 2022 2021 Method Percentage ​ Nanjing JinMei Gallium Co., Ltd. ​ $ 592 ​ $ 592 Consolidated **85.5 % ChaoYang JinMei Gallium Co., Ltd. ​ ​ 1,820 ​ ​ 1,820 ​ Consolidated ​ **85.5 % Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd. ​ 1,346 ​ 1,346 Consolidated **85.5 % ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd. ​ ​ 4,642 ​ ​ 1,814 ​ Consolidated ***58.5 % ​ ​ $ 8,400 ​ $ 5,572 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Donghai County Dongfang High Purity Electronic Materials Co., Ltd. ​ $ 2,057 ​ $ 2,053 Equity **46 % Beijing JiYa Semiconductor Material Co., Ltd. ​ ​ 4,292 ​ ​ 3,760 ​ Equity ​ 39 % Xilingol Tongli Germanium Co., Ltd. ​ — ​ — Equity 25 % Xiaoyi XingAn Gallium Co., Ltd. ​ ​ 4,739 ​ ​ 4,095 ​ Equity ​ **25 % Emeishan Jia Mei High Purity Metals Co., Ltd. ​ 224 ​ 258 Equity 25 % ​ ​ $ 11,312 ​ $ 10,166 ​ ​ ​ ​ ​ ​ * These ​ ** In preparation for Tongmei’s application for a listing of shares in an IPO on the STAR Market, in late December 2020 we reorganized our entity structures in China. JinMei and BoYu and its subsidiaries, previously organized under AXT, Inc., were assigned to Tongmei and effectively merged with Tongmei although they retained their own respective legal entity status and are wholly owned subsidiaries of Tongmei. The minority interest in Tongmei. The ​ ***
Summarized equity method income information	AXT’s minority investment entities are not consolidated and are accounted for under the equity method. Excluding one fully impaired entity, the equity investment entities had the following summarized statements of operations information (in thousands) for the three months ended March 31, 2022 and 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2022 2021 Net revenue ​ $ 10,734 ​ $ 8,525 ​ Gross profit ​ $ 5,999 ​ $ 3,807 ​ Operating income ​ $ 4,149 ​ $ 3,061 ​ Net income ​ $ 3,698 ​ $ 2,612 ​

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2022
Stockholders' Equity
Consolidated statements of stockholders' equity	The changes in stockholders’ equity by component for the three months ended March 31, 2022 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other ​ AXT, Inc. Total ​ ​ Preferred Common Additional Accumulated Comprehensive ​ Stockholders’ Noncontrolling Stockholders’ ​ ​ Stock Stock Paid-In Capital Deficit Income (Loss) Equity Interests Equity Balance as of December 31, 2021 $ 3,532 $ 43 $ 231,622 $ (29,970) $ 6,302 ​ $ 211,529 $ 18,317 $ 229,846 ​ Investment in subsidiary with noncontrolling interest ​ ​ — ​ ​ — ​ ​ (410) ​ ​ — ​ ​ — ​ ​ (410) ​ ​ 204 ​ ​ (206) ​ Noncontrolling interest portion of Tongmei stock-based compensation ​ ​ — ​ ​ — ​ ​ 17 ​ ​ — ​ ​ — ​ ​ 17 ​ ​ (7) ​ ​ 10 ​ Stock-based compensation ​ ​ — ​ ​ — ​ ​ 875 ​ ​ — ​ ​ — ​ ​ 875 ​ ​ — ​ ​ 875 ​ Tongmei stock-based compensation ​ ​ — ​ ​ — ​ ​ 213 ​ ​ — ​ ​ — ​ ​ 213 ​ ​ — ​ ​ 213 ​ Net income ​ ​ — ​ ​ — ​ ​ — ​ ​ 3,165 ​ ​ — ​ ​ 3,165 ​ ​ 389 ​ ​ 3,554 ​ Investment in subsidiary from noncontrolling interest ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 1,887 ​ ​ 1,887 ​ Other comprehensive income ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 327 ​ ​ 327 ​ ​ 45 ​ ​ 372 ​ Balance as of March 31, 2022 $ 3,532 ​ $ 43 ​ $ 232,317 ​ $ (26,805) ​ $ 6,629 ​ $ 215,716 ​ $ 20,835 ​ $ 236,551 ​ ​ Net income and other comprehensive income attributable to redeemable noncontrolling interests was $418,000 and $46,000, respectively, not shown in the table above. The changes in stockholders’ equity by component for the three months ended March 31, 2021 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other ​ AXT, Inc. Total ​ Preferred Common Additional Accumulated Comprehensive ​ Stockholders’ Noncontrolling Stockholders’ ​ Stock Stock Paid-In Capital Deficit Income (Loss) Equity Interests Equity Balance as of December 31, 2020 $ 3,532 $ 42 $ 230,381 $ (44,545) $ 3,209 ​ $ 192,619 $ 15,350 $ 207,969 Common stock options exercised ​ ​ — ​ ​ — ​ ​ 704 ​ ​ — ​ ​ — ​ ​ 704 ​ ​ — ​ ​ 704 Stock-based compensation ​ ​ — ​ ​ — ​ ​ 816 ​ ​ — ​ ​ — ​ ​ 816 ​ ​ — ​ ​ 816 Formation of new subsidiary with noncontrolling interests ​ ​ — ​ ​ — ​ ​ (131) ​ ​ — ​ ​ — ​ ​ (131) ​ ​ 707 ​ ​ 576 Sale of common stock to employees in connection with the reorganization ​ ​ — ​ ​ — ​ ​ 538 ​ ​ — ​ ​ — ​ ​ 538 ​ ​ — ​ ​ 538 Purchase of subsidiary shares from noncontrolling interests ​ ​ — ​ ​ — ​ ​ (2,691) ​ ​ — ​ ​ — ​ ​ (2,691) ​ ​ (1,039) ​ ​ (3,730) Net income (loss) ​ ​ — ​ ​ — ​ ​ — ​ ​ 3,425 ​ ​ — ​ ​ 3,425 ​ ​ 311 ​ ​ 3,736 Other comprehensive loss ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (131) ​ ​ (131) ​ ​ (16) ​ ​ (147) Balance as of March 31, 2021 ​ $ 3,532 ​ $ 42 ​ $ 229,617 ​ $ (41,120) ​ $ 3,078 ​ $ 195,149 ​ $ 15,313 ​ $ 210,462

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2022
Stock-Based Compensation
Summary of compensation costs related to stock-based awards	The following table summarizes compensation costs related to our stock-based awards (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ ​ March 31, ​ ​ 2022 2021 Cost of revenue ​ ​ $ 113 ​ $ 39 ​ Selling, general and administrative ​ ​ 811 ​ 640 ​ Research and development ​ ​ 164 ​ 137 ​ Total stock-based compensation ​ ​ 1,088 ​ 816 ​ Tax effect on stock-based compensation ​ ​ — ​ — ​ Net effect on net income ​ ​ $ 1,088 ​ $ 816 ​
Summary of stock option activity	The following table summarizes the stock option transactions during the three months ended March 31, 2022 (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ ​ average ​ ​ ​ ​ ​ ​ Weighted- ​ Remaining ​ ​ ​ ​ ​ Number of ​ average ​ Contractual ​ Aggregate ​ ​ Options ​ Exercise ​ Life ​ Intrinsic Stock Options Outstanding Price (in years) Value Balance as of January 1, 2022 1,378 ​ $ 4.83 5.60 ​ $ 5,573 ​ Granted — ​ — ​ ​ ​ ​ ​ ​ Exercised — ​ ​ — ​ ​ ​ ​ ​ ​ Canceled and expired — ​ ​ — ​ ​ ​ ​ ​ ​ Balance as of March 31, 2022 1,378 ​ $ 4.83 5.36 ​ $ 3,383 ​ Options vested as of March 31, 2022 and unvested options expected to vest, net of forfeitures 1,376 ​ $ 4.83 5.35 ​ $ 3,371 ​ Options exercisable as of March 31, 2022 1,140 ​ $ 5.10 4.92 ​ $ 2,547 ​
Summary of restricted stock awards activity	A summary of activity related to restricted stock awards for the three months ended March 31, 2022 is presented below (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ Grant Date Stock Awards Shares Share Value Non-vested as of January 1, 2022 ​ 875 ​ $ 6.26 ​ Granted 2 ​ $ 9.05 ​ Vested (9) ​ $ 11.60 ​ Forfeited ​ (8) ​ $ 5.21 ​ Non-vested as of March 31, 2022 860 ​ $ 6.22 ​
Summary of unvested at-risk performance shares	A summary of the status of our unvested at-risk, performance shares as of March 31, 2022 is presented below (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ Grant Date Stock Awards Shares* Share Value Non-vested as of January 1, 2022 ​ 114 ​ $ 15.37 Granted 74 ** $ 10.91 Vested — ​ $ — Forfeited ​ — ​ $ — Non-vested as of March 31, 2022 188 ​ $ 12.42 ​ *The number of shares presented is based on achieving 150% of the targeted financial performance metric as defined in the at-risk, performance shares agreement. ​ ** The first annual vesting was reported in Q4 2021, when 25% of the at-risk performance shares became eligible subject to review and confirmation by the Compensation Committee after year-end results were certified.

Net Income (Loss) Per Share (Ta

Net Income (Loss) Per Share (Tables)	3 Months Ended
	Mar. 31, 2022
Net Income (Loss) Per Share
Reconciliation of numerators and denominators of basic and diluted net income (loss) per share	A reconciliation of the numerators and denominators of the basic and diluted net income (loss) per share calculations is as follows (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ ​ March 31, ​ ​ 2022 2021 Numerator: ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to AXT, Inc. ​ ​ $ 3,165 ​ $ 3,425 ​ Less: Preferred stock dividends ​ ​ (44) ​ (44) ​ Net income available to common stockholders ​ ​ $ 3,121 ​ $ 3,381 ​ Denominator: ​ ​ ​ ​ ​ ​ ​ ​ Denominator for basic net income per share - weighted-average common shares ​ ​ 41,871 ​ 41,004 ​ Effect of dilutive securities: ​ ​ ​ ​ ​ ​ ​ ​ Common stock options ​ ​ 474 ​ 1,082 ​ Restricted stock awards ​ ​ 317 ​ 640 ​ Denominator for dilutive net income per common shares ​ ​ 42,662 ​ 42,726 ​ Net income attributable to AXT, Inc. per common share: ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ ​ $ 0.07 ​ $ 0.08 ​ Diluted ​ ​ $ 0.07 ​ $ 0.08 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options excluded from diluted net income (loss) per share as the impact is anti-dilutive ​ ​ 201 ​ 21 ​ Restricted stock excluded from diluted net income (loss) per share as the impact is anti-dilutive ​ ​ 218 ​ 57 ​

Segment Information and Forei_2

Segment Information and Foreign Operations (Tables)	3 Months Ended
	Mar. 31, 2022
Segment Information and Foreign Operations
Revenues reported by product type	The following table represents revenue amounts (in thousands) by product type: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ ​ March 31, ​ ​ ​ 2022 2021 Product Type: ​ ​ ​ ​ ​ ​ ​ ​ Substrates ​ $ 31,745 ​ $ 23,373 ​ ​ Raw Materials and Other ​ 7,908 ​ 7,977 ​ ​ Total ​ $ 39,653 ​ $ 31,350 ​ ​
Revenue reported for products shipped to customers in the corresponding geographic region	The following table represents revenue amounts (in thousands) reported for products shipped to customers in the corresponding geographic region: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ ​ March 31, ​ ​ ​ 2022 2021 Geographical region: ​ ​ ​ ​ ​ ​ ​ ​ China ​ $ 17,480 ​ $ 15,546 ​ ​ Taiwan ​ ​ 6,859 ​ ​ 3,015 ​ ​ Japan ​ 2,807 ​ 2,523 ​ ​ Asia Pacific (excluding China, Taiwan and Japan) ​ ​ 1,756 ​ ​ 1,817 ​ ​ Europe (primarily Germany) ​ ​ 6,394 ​ ​ 5,435 ​ ​ North America (primarily the United States) ​ 4,357 ​ 3,014 ​ ​ Total ​ $ 39,653 ​ $ 31,350 ​ ​
Long-lived assets by geographic region	Long-lived assets consist primarily of property, plant and equipment and operating lease right-of-use assets, and are attributed to the geographic location in which they are located. Long-lived assets, net of depreciation, by geographic region were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of ​ ​ ​ March 31, ​ December 31, ​ ​ 2022 2021 Long-lived assets by geographic region, net of depreciation: ​ ​ ​ ​ ​ ​ ​ North America ​ $ 897 ​ $ 1,610 ​ China ​ 148,612 ​ 143,129 ​ ​ ​ $ 149,509 ​ $ 144,739 ​

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2022
Commitments and Contingencies
Product warranty accrued liability	​ The following table reflects the change in our warranty accrual which is included in “Accrued liabilities” in the condensed consolidated balance sheets, during the three months ended March 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2022 2021 Beginning accrued product warranty ​ $ 743 ​ $ 609 ​ Accruals for warranties issued ​ 556 ​ 113 ​ Adjustments related to pre-existing warranties including expirations and changes in estimates ​ (113) ​ (54) ​ Cost of warranty repair ​ (354) ​ (86) ​ Ending accrued product warranty ​ $ 832 ​ $ 582 ​

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2022
Revenue
Schedule of amounts recorded in accrued liabilities	The following table reflects the contract liabilities balance, which is included in “Accrued liabilities” on the condensed consolidated balance sheets, as of March 31, 2022 and December 31, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ ​ ​ 2022 ​ 2021 ​ Contract liabilities ​ $ 1,024 ​ $ 946 ​ During the three months ended March 31, 2022, the Company recognized $321,000 of revenue that was included in the contract balances as of December 31, 2021. ​ ​ ​ ​ ​ ​

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2022
Leases
Summary of maturities of our operating lease liabilities	As of March 31, 2022, the maturities of our operating lease liabilities (excluding short-term leases) are as follows (in thousands): ​ ​ ​ ​ Maturity of Lease Liabilities ​ 2022 $ 444 2023 ​ 582 2024 ​ 293 2025 ​ 293 2026 ​ 293 Thereafter ​ 757 Total minimum lease payments ​ 2,662 Less: Interest ​ (353) Present value of lease obligations ​ 2,309 Less: Current portion, included in accrued liabilities ​ (499) Long-term portion of lease obligations $ 1,810
Schedule of weighted-average remaining lease term and the weighted-average discount rate of operating leases	​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ ​ ​ 2022 ​ 2021 ​ Weighted-average remaining lease term (years) ​ 6.29 ​ 6.44 ​ Weighted-average discount rate ​ 4.61 % 4.61 %
Schedule of supplemental cash flow information related to leases	Supplemental cash flow information related to leases where we are the lessee is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ ​ 2022 ​ 2021 ​ Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ 147 ​ $ 141 ​
Summary of components of lease expense	The components of lease expense are as follows (in thousands) within our condensed consolidated statements of operations: ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, ​ ​ 2022 ​ 2021 Operating lease ​ $ 134 ​ $ 133 Short-term lease expense ​ ​ 36 ​ ​ 24 Total ​ $ 170 ​ $ 157

Redeemable Noncontrolling Int_2

Redeemable Noncontrolling Interests (Tables)	3 Months Ended
	Mar. 31, 2022
Redeemable Noncontrolling Interests
Components of the change in redeemable noncontrolling interests	The components of the change in redeemable noncontrolling interests for the three months ended March 31, 2022 are presented in the following table (in thousands): ​ ​ ​ Balance as of January 1, 2022 $ 50,385 Investment in subsidiary with redeemable noncontrolling interest ​ 206 Equity issuance costs incurred ​ (227) Stock-based compensation attributable to redeemable noncontrolling interests ​ (6) Net income attributable to redeemable noncontrolling interests ​ 418 Effect of foreign currency translation on redeemable noncontrolling interests ​ 149 Effect of foreign currency translation attributable to redeemable noncontrolling interests ​ 46 Balance as of March 31, 2022 $ 50,971

Basis of Presentation (Details)

Basis of Presentation (Details) $ in Thousands

Jan. 25, 2021USD ($)

Jun. 30, 2021USD ($)

May 31, 2021USD ($)

Feb. 28, 2021USD ($)

Jan. 31, 2021USD ($)

Mar. 31, 2022USD ($)company

Dec. 31, 2021USD ($)company

Dec. 31, 2020USD ($)

Jan. 31, 2022USD ($)

Oct. 31, 2021USD ($)

Sep. 30, 2021USD ($)

Nov. 30, 2020

May 31, 2019

Apr. 30, 2019

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Number of equity method investments | company

5

5

Investments, equity method

$ 11,312

$ 10,166

AXT-Tongmei, Inc | Disposal Group, Disposed of by Sale, Not Discontinued Operations

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Cash consideration

$ 1,000

ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd | Loan from related party | ChaoYang Xinshuo

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Loan amount

$ 1,000

$ 900

ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Investment value, agreement amount

$ 1,800

$ 3,000

Investments, equity method

$ 1,800

Ownership (as a percent)

58.50%

58.50%

58.50%

Initial funding

$ 1,500

$ 1,500

Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd Investment

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Percentage of outstanding shares

33.00%

Percentage of ownership

67.00%

63.00%

Beijing Tongmei Xtal Technology

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Percentage of outstanding shares

7.28%

14.50%

Private equity ownership percentage

7.28%

14.50%

Percentage of key managers and contributors purchased

0.40%

Investment in new facility

$ 49,000

$ 48,100

Raised additional capital

$ 1,500

Percentage of ownership

85.50%

Transaction results in increase to noncontrolling interests

$ 1,200

Transaction results in increase to redeemable noncontrolling interests

$ 1,200

Beijing Tongmei Xtal Technology | Beijing Boyu Semiconductor Vessel Craftwork Technology Co Ltd

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Private equity ownership percentage

7.59%

Beijing Tongmei Xtal Technology | Nanjing JinMei Gallium Co., Ltd

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Private equity ownership percentage

0.38%

Beijing Tongmei Xtal Technology | ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Loan amount

$ 1,400

$ 1,400

Beijing Tongmei Xtal Technology | ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Investment amount

$ 900

$ 900

Nanjing JinMei Gallium Co., Ltd Investment

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Percentage of outstanding shares

8.50%

Percentage of ownership

100.00%

97.00%

Nanjing JinMei Gallium Co., Ltd Investment | Nanjing JinMei Gallium Co., Ltd

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Private equity ownership percentage

0.38%

Investments and Fair Value Me_3

Investments and Fair Value Measurements (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Cash, cash equivalents and investments [Abstract]
Cash	$ 29,494	$ 36,763
Cash equivalents [Abstract]
Total cash and cash equivalents	29,494	36,763
Amortized Cost	15,036	15,060
Cash, cash equivalents and investments, amortized costs	44,531	51,823
Gross Unrealized (Loss)	(237)	(65)
Fair Value	14,800	14,995
Cash, cash equivalents and investments, amortized costs	44,294	51,758
Contractual maturities on investments, amortized cost basis [Abstract]
Due within 1 year	5,409	5,424
Due after 1 through 5 years	9,627	9,636
Investments, amortized cost	15,036	15,060
Contractual maturities on investments, fair value basis [Abstract]
Due within 1 year	5,400	5,419
Due after 1 through 5 years	9,400	9,576
Investments, fair value	14,800	14,995
Total Investments [Member]
Cash equivalents [Abstract]
Amortized Cost	15,037	15,060
Gross Unrealized (Loss)	(237)	(65)
Fair Value	14,800	14,995
Contractual maturities on investments, amortized cost basis [Abstract]
Investments, amortized cost	15,037	15,060
Contractual maturities on investments, fair value basis [Abstract]
Investments, fair value	14,800	14,995
Certificates of Deposit [Member]
Cash equivalents [Abstract]
Amortized Cost	6,680	6,680
Gross Unrealized (Loss)	(90)	(19)
Fair Value	6,590	6,661
Contractual maturities on investments, amortized cost basis [Abstract]
Investments, amortized cost	6,680	6,680
Contractual maturities on investments, fair value basis [Abstract]
Investments, fair value	6,590	6,661
Corporate Bonds [Member]
Cash equivalents [Abstract]
Amortized Cost	8,357	8,380
Gross Unrealized (Loss)	(147)	(46)
Fair Value	8,210	8,334
Contractual maturities on investments, amortized cost basis [Abstract]
Investments, amortized cost	8,357	8,380
Contractual maturities on investments, fair value basis [Abstract]
Investments, fair value	$ 8,210	$ 8,334

Investments and Fair Value Me_4

Investments and Fair Value Measurements - Investment Category and Length (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022USD ($)company	Mar. 31, 2021USD ($)	Dec. 31, 2021USD ($)company
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	$ 11,447		$ 12,151
Gross unrealized (loss), in loss position less than twelve months	(229)		(61)
Fair value, in loss position greater than twelve months	3,002		2,013
Gross unrealized (loss), in loss position greater than twelve months	(7)		(4)
Fair value, total in loss position	14,449		14,164
Gross unrealized (loss), total in loss position	(236)		(65)
Minority Investments
Investments, equity method	$ 11,312		$ 10,166
Number of equity method investments | company	5		5
Impairment charge	$ 0	$ 0
Certificates of Deposit [Member]
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	6,590		$ 6,181
Gross unrealized (loss), in loss position less than twelve months	(90)		(19)
Fair value, total in loss position	6,590		6,181
Gross unrealized (loss), total in loss position	(90)		(19)
Corporate Bonds [Member]
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	4,857		5,970
Gross unrealized (loss), in loss position less than twelve months	(139)		(42)
Fair value, in loss position greater than twelve months	3,002		2,013
Gross unrealized (loss), in loss position greater than twelve months	(7)		(4)
Fair value, total in loss position	7,859		7,983
Gross unrealized (loss), total in loss position	(146)		(46)
Other Assets [Member]
Minority Investments
Investments, equity method	$ 11,300		$ 10,200

Investments and Fair Value Me_5

Investments and Fair Value Measurements - Recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Assets, Fair Value Disclosure [Abstract]
Investments, amortized cost	$ 14,800	$ 14,995
Fair Value, Transfers Between Level 1 and Level 2, Description and Policy [Abstract]
Transfer from Level 1 to Level 2 , assets	0
Transfer from Level 2 to Level 1 , assets	0
Transfers into Level 3, assets	0
Transfer out of Level 3, assets	0
Recurring [Member]
Assets, Fair Value Disclosure [Abstract]
Total	14,800	14,995
Recurring [Member] | Certificates of Deposit [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents, fair value disclosure	6,590	6,661
Recurring [Member] | Corporate Bonds [Member]
Assets, Fair Value Disclosure [Abstract]
Investments, amortized cost	8,210	8,334
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets, Fair Value Disclosure [Abstract]
Total	14,800	14,995
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Certificates of Deposit [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents, fair value disclosure	6,590	6,661
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate Bonds [Member]
Assets, Fair Value Disclosure [Abstract]
Investments, amortized cost	$ 8,210	$ 8,334

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Inventories
Raw materials	$ 32,949	$ 29,658
Work in process	32,411	32,605
Finished goods	3,461	3,649
Inventories, Total	68,821	65,912
Inventory reserve	20,600	19,600
Excess and obsolete inventory	$ 70,000	$ 66,000

Property, Plant and Equipment_3

Property, Plant and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Property, plant and equipment
Property, plant and equipment, net	$ 147,286		$ 142,415
Depreciation and amortization	1,983	$ 1,596
Machinery and equipment
Property, plant and equipment
Property, plant and equipment, gross	59,617		59,284
Less: accumulated depreciation and amortization	(40,848)		(40,292)
Building
Property, plant and equipment
Property, plant and equipment, gross	109,071		108,782
Less: accumulated depreciation and amortization	(19,560)		(18,710)
Leasehold improvements
Property, plant and equipment
Property, plant and equipment, gross	7,060		7,039
Less: accumulated depreciation and amortization	(5,521)		(5,352)
Construction in progress
Property, plant and equipment
Property, plant and equipment, gross	37,467		31,664
Construction in progress Dingxin and Kazuo locations
Property, plant and equipment
Property, plant and equipment, gross	27,200		22,700
Construction in progress manufacturing equipment purchases
Property, plant and equipment
Property, plant and equipment, gross	4,300		3,000
Construction in progress other consolidated subsidiaries
Property, plant and equipment
Property, plant and equipment, gross	$ 6,100		$ 6,000

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Components of accrued liabilities
Accrued compensation and related charges	$ 3,436	$ 5,115
Preferred stock dividends payable	2,901	2,901
Advances from customers	1,024	946
Accrued income taxes	1,001	539
Accrued product warranty	832	743
Current portion of operating lease liabilities	499	488
Accrued professional services	423	880
Other personnel-related costs	278	279
Payable in connection with construction in progress	268	2,974
Other tax payable	230	392
Accrual for sales returns	20	48
Other accrued liabilities	1,301	1,752
Accrued liabilities, Total	$ 12,213	$ 17,057

Related Party Transactions (Det

Related Party Transactions (Details)	1 Months Ended						3 Months Ended
	Jan. 31, 2022USD ($)	Dec. 31, 2021USD ($)	Oct. 31, 2021USD ($)	Sep. 30, 2021USD ($)	Jul. 31, 2021USD ($)	Jul. 31, 2017USD ($)installment	Mar. 31, 2022USD ($)ft²
Related Party Transaction [Line Items]
Area of leased property (in square feet) | ft²							19,467
Donghai County Dongfang High Purity Electronic Materials Co., Ltd | Raw materials purchases from related party | Accounts payable | Beijing Tongmei Xtal Technology
Related Party Transaction [Line Items]
Amount payable to related party		$ 112,000					$ 112,000
Beijing BoYu Semiconductor Vessel Craftwork Technology Co | Lease of land | Beijing Tongmei Xtal Technology
Related Party Transaction [Line Items]
Area of leased property (in square feet) | ft²							22,081
Lease term	11 years						10 years
Annual lease payment	$ 27,000						$ 24,000
Increase in annual lease payment at each third year anniversary (in hundredths)	5.00%						5.00%
Rental increase period							3 years
Nanjing JinMei Gallium Co., Ltd | Related party loan | Beijing Tongmei Xtal Technology
Related Party Transaction [Line Items]
Number of installments | installment						3
Related party notes receivable - long term						$ 768,000
Amount payable to related party		0					$ 0
Interest rate (as a percent)						4.90%
Repayment of related party notes receivable					$ 858,000
ChaoYang Xinshuo | Loan from related party | ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd
Related Party Transaction [Line Items]
Amount of transaction			$ 1,000,000	$ 900,000
Long term debt, related party							$ 0
Beijing Tongmei Xtal Technology | Loan from related party | ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd
Related Party Transaction [Line Items]
Amount of transaction	$ 1,400,000	$ 1,400,000
Ownership (as a percent)	58.50%
Short-term loan from noncontrolling interest	$ 0
Increase in redeemable noncontrolling interests	200,000
Increase in noncontrolling interest	$ 2,200,000

Investments in Privately-Held_3

Investments in Privately-Held Raw Material Companies (Details)

Jan. 25, 2021USD ($)

Jun. 15, 2018USD ($)installment

Nov. 02, 2017USD ($)

Jun. 30, 2021USD ($)

Jan. 31, 2021USD ($)

Aug. 31, 2020USD ($)

May 31, 2019USD ($)

Sep. 30, 2018USD ($)employeeentity

Mar. 31, 2022USD ($)employee

Mar. 31, 2021USD ($)

Dec. 31, 2020USD ($)employee

Dec. 31, 2021USD ($)

Nov. 30, 2020

Jul. 31, 2020

Jun. 01, 2019USD ($)

Apr. 30, 2019

Aug. 31, 2018

Jun. 14, 2018

Nov. 01, 2017

Summary of investments

Investments, equity method

$ 11,312,000

$ 10,166,000

Noncontrolling interests

20,835,000

18,317,000

Number of persons on board | employee

1

Impairment charge

0

$ 0

Joint Ventures [Member]

Summary of investments

Number of consolidated joint ventures | entity

3

Other Assets [Member]

Summary of investments

Investments, equity method

11,300,000

10,200,000

Xiaoyi XingAn Gallium Co., Ltd.

Summary of investments

Dividend received

$ 774,000

Donghai County Dongfang High Purity Electronic Materials Co., Ltd Investment | Donghai County Dongfang High Purity Electronic Materials Co., Ltd Investment

Summary of investments

Investments, equity method

$ 2,057,000

2,053,000

Percentage of ownership, equity method

46.00%

Beijing JiYa Semiconductor Material Co., Ltd Investment | Beijing JiYa Semiconductor Material Co., Ltd Investment

Summary of investments

Investments, equity method

$ 4,292,000

3,760,000

Percentage of ownership, equity method

39.00%

Xilingol Tongli Germanium Co. Ltd Investment | Xilingol Tongli Germanium Co. Ltd Investment

Summary of investments

Percentage of ownership, equity method

25.00%

Xiaoyi XingAn Gallium Co., Ltd. | Xiaoyi XingAn Gallium Co., Ltd.

Summary of investments

Investments, equity method

$ 4,739,000

4,095,000

Percentage of ownership, equity method

25.00%

Emeishan Jia Mei High Purity Metals Co., Ltd Investment | Emeishan Jia Mei High Purity Metals Co., Ltd Investment

Summary of investments

Investments, equity method

$ 224,000

258,000

Percentage of ownership, equity method

25.00%

Nanjing JinMei Gallium Co., Ltd Investment

Summary of investments

Percentage of ownership, consolidated method (in hundredths)

100.00%

97.00%

Percentage of outstanding shares

8.50%

Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd Investment

Summary of investments

Percentage of ownership, consolidated method (in hundredths)

67.00%

63.00%

Percentage of outstanding shares

33.00%

Beijing Tongmei Xtal Technology

Summary of investments

Percentage of ownership, consolidated method (in hundredths)

85.50%

Percentage of outstanding shares

7.28%

14.50%

Private equity ownership percentage

7.28%

14.50%

Percentage of key managers and contributors purchased

0.40%

Increase in redeemable noncontrolling interests

$ 1,500,000

$ 48,100,000

Investments, government approved

$ 49,000,000

Raised additional capital

$ 1,500,000

Nanjing JinMei Gallium Co., Ltd

Summary of investments

Number of new board representatives | employee

2

Nanjing JinMei Gallium Co., Ltd | Nanjing JinMei Gallium Co., Ltd Investment

Summary of investments

Private equity ownership percentage

0.38%

Nanjing JinMei Gallium Co., Ltd | Beijing Tongmei Xtal Technology

Summary of investments

Private equity ownership percentage

0.38%

Beijing Boyu Semiconductor Vessel Craftwork Technology Co Ltd

Summary of investments

Number of new board representatives | employee

2

Beijing Boyu Semiconductor Vessel Craftwork Technology Co Ltd | Beijing Tongmei Xtal Technology

Summary of investments

Private equity ownership percentage

7.59%

Majority-Owned Subsidiaries [Member]

Summary of investments

Investments, consolidated method

$ 8,400,000

5,572,000

Nanjing JinMei Gallium Co., Ltd Investment

Summary of investments

Investments, consolidated method

$ 592,000

592,000

Additional percentage of ownership, consolidated method

12

3

2

Purchase of subsidiary shares from noncontrolling interest

$ 1,400,000

$ 413,000

$ 252,000

Number of installments | installment

2

Payment of first installment

$ 163,000

Payment of second installment

$ 1,200,000

Noncontrolling interests

$ 0

Nanjing JinMei Gallium Co., Ltd Investment | Nanjing JinMei Gallium Co., Ltd Investment

Summary of investments

Percentage of ownership, consolidated method (in hundredths)

95.00%

97.00%

85.50%

95.00%

83.00%

ChaoYang Jin Mei Gallium Co., Ltd [Member]

Summary of investments

Investments, consolidated method

$ 1,820,000

1,820,000

ChaoYang Jin Mei Gallium Co., Ltd [Member] | ChaoYang Jin Mei Gallium Co., Ltd [Member]

Summary of investments

Percentage of ownership, consolidated method (in hundredths)

91.50%

85.50%

100.00%

Percentage of ownership interest sold

8.50%

Proceeds from sale of previously consolidated subsidiary shares

$ 396,000

Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd Investment

Summary of investments

Investments, consolidated method

$ 1,346,000

1,346,000

Additional percentage of ownership, consolidated method

4

Purchase of subsidiary shares from noncontrolling interest

$ 1,600,000

Gain (loss) from equity transaction

$ 0

Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd Investment | 3rd Party Investor

Summary of investments

Percentage ownership from issuance of shares

10.00%

Raised additional capital

$ 2,000,000

Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd Investment | Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd Investment

Summary of investments

Percentage of ownership, consolidated method (in hundredths)

63.00%

85.50%

70.00%

ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd

Summary of investments

Investments, consolidated method

$ 4,642,000

$ 1,814,000

ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd | ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd

Summary of investments

Percentage of ownership, consolidated method (in hundredths)

58.50%

Investments in Privately-Held_4

Investments in Privately-Held Raw Material Companies - Minority Investment Entities (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)entity	Mar. 31, 2021USD ($)
Summarized income information of all the minority investment entities that are not consolidated and accounted for under the equity method [Abstract]
Revenue	$ 39,653	$ 31,350
Gross profit	13,308	11,536
Net income	$ 3,972	3,765
Minority investment entities
Impaired entities | entity	1
Five Minority Investments
Summarized income information of all the minority investment entities that are not consolidated and accounted for under the equity method [Abstract]
Revenue	$ 10,734	8,525
Gross profit	5,999	3,807
Operating income	4,149	3,061
Net income	3,698	2,612
Minority investment entities
Entity income (loss) excluding impairment	$ 1,100	$ 1,100

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended	72 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2015	Dec. 31, 2021	Oct. 27, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	$ 229,846	$ 207,969
Common stock options exercised		704
Stock-based compensation	875	816
Investment in subsidiary with noncontrolling interest	(206)	(576)
Noncontrolling interest portion of Tongmei stock-based compensation	10
Sale of common stock to employees in connection with the reorganization		538
Tongmei stock-based compensation	213
Net income (loss)	3,554	3,736
Investment in subsidiary from noncontrolling interest	1,887
Other comprehensive income (loss)	372	(147)
Purchase of subsidiary shares from noncontrolling interests		(3,730)
Balance, end of period	236,551	210,462		$ 229,846
Reclassification adjustment from AOCI	0	0
Net income attributable to redeemable noncontrolling interests	418
Other comprehensive income attributable to redeemable noncontrolling interests	$ 46
Stock repurchase program, authorized amount					$ 5,000
Shares repurchased (in shares)	0		908,000	0
Average price of shares repurchased (in dollars per share)			$ 2.52
Total purchase price			$ 2,300
Stock repurchase program remaining authorized repurchase amount	$ 2,700
Preferred Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	3,532	3,532
Balance, end of period	3,532	3,532		$ 3,532
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	43	42
Balance, end of period	43	42		43
Additional Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	231,622	230,381
Common stock options exercised		704
Stock-based compensation	875	816
Investment in subsidiary with noncontrolling interest	(410)	131
Noncontrolling interest portion of Tongmei stock-based compensation	17
Sale of common stock to employees in connection with the reorganization		538
Tongmei stock-based compensation	213
Purchase of subsidiary shares from noncontrolling interests		(2,691)
Balance, end of period	232,317	229,617		231,622
Accumulated Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(29,970)	(44,545)
Net income (loss)	3,165	3,425
Balance, end of period	(26,805)	(41,120)		(29,970)
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	6,302	3,209
Other comprehensive income (loss)	327	(131)
Balance, end of period	6,629	3,078		6,302
AXT, Inc. Stockholders' Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	211,529	192,619
Common stock options exercised		704
Stock-based compensation	875	816
Investment in subsidiary with noncontrolling interest	(410)	131
Noncontrolling interest portion of Tongmei stock-based compensation	17
Sale of common stock to employees in connection with the reorganization		538
Tongmei stock-based compensation	213
Net income (loss)	3,165	3,425
Other comprehensive income (loss)	327	(131)
Purchase of subsidiary shares from noncontrolling interests		(2,691)
Balance, end of period	215,716	195,149		211,529
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	18,317	15,350
Investment in subsidiary with noncontrolling interest	204	(707)
Noncontrolling interest portion of Tongmei stock-based compensation	(7)
Net income (loss)	389	311
Investment in subsidiary from noncontrolling interest	1,887
Other comprehensive income (loss)	45	(16)
Purchase of subsidiary shares from noncontrolling interests		(1,039)
Balance, end of period	$ 20,835	$ 15,313		$ 18,317

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 1,088	$ 816
Net effect on net income	1,088	816
Cost of Revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	113	39
Selling, General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	811	640
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 164	$ 137

Stock-Based Compensation - Opti

Stock-Based Compensation - Options (Details) - Options [Member] - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation costs related to unvested stock options not yet recognized	$ 300,000
Value of estimated forfeitures	$ 35,000
Weighted-average period of amortization	1 year 4 months 24 days
Number of Options Outstanding [Roll Forward]
Options outstanding, beginning of period (in shares)	1,378
Granted (in shares)	0	0
Options outstanding, end of period (in shares)	1,378		1,378
Options vested and unvested options expected to vest, net of forfeitures, end of period (in shares)	1,376
Options exercisable, end of period (in shares)	1,140
Weighted-average Exercise Price [Roll Forward]
Options outstanding, beginning of period (in dollars per share)	$ 4.83
Options outstanding, end of period (in dollars per share)	4.83		$ 4.83
Options vested and unvested options expected to vest, net of forfeitures (in dollars per share)	4.83
Options exercisable, end of period (in dollars per share)	$ 5.10
Weighted average Remaining Contractual Life [Abstract]
Options outstanding	5 years 4 months 9 days		5 years 7 months 6 days
Options vested and unvested options expected to vest, net of forfeitures, end of period	5 years 4 months 6 days
Option exercisable, end of period	4 years 11 months 1 day
Aggregate Intrinsic Value [Abstract]
Options outstanding, beginning of period	$ 5,573,000
Options outstanding, end of period	3,383,000		$ 5,573,000
Options vested and expected to vest, end of period	3,371,000
Options exercisable, end of period	$ 2,547,000
Closing price (in dollars per share)	$ 7.02

Stock-Based Compensation - RSU

Stock-Based Compensation - RSU (Details) - Restricted Stock Awards [Member] $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2022USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation costs related to unvested stock options not yet recognized | $	$ 4.3
Weighted-average period of amortization	1 year 4 months 24 days
Shares [Roll Forward]
Non-vested, beginning of period (in shares) | shares	875
Granted (in shares) | shares	2
Vested (in shares) | shares	(9)
Forfeited (in shares) | shares	(8)
Non-vested, end of period (in shares) | shares	860
Weighted Average Grant Date Fair Value [Roll Forward]
Non-vested, beginning of period (in dollars per share) | $ / shares	$ 6.26
Granted (in dollars per share) | $ / shares	9.05
Vested (in dollars per share) | $ / shares	11.60
Forfeited (in dollars per share) | $ / shares	5.21
Non-vested, end of period (in dollars per share) | $ / shares	$ 6.22

Stock-Based Compensation - Perf

Stock-Based Compensation - Performance Shares (Details) - Performance Shares - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	Mar. 14, 2022	Feb. 15, 2022	Feb. 17, 2021	Feb. 28, 2022	Feb. 28, 2021	Mar. 31, 2022	Dec. 31, 2021
Shares [Roll Forward]
Non-vested, beginning of period (in shares)						114
Granted (in shares)						74
Non-vested, end of period (in shares)						188	114
Weighted Average Grant Date Fair Value [Roll Forward]
Non-vested, beginning of period (in dollars per share)						$ 15.37
Granted (in dollars per share)						10.91
Non-vested, end of period (in dollars per share)						$ 12.42	$ 15.37
Weighted-average grant date fair value of stock options granted (in dollars per share)				$ 7.83	$ 15.37
Percentage of year-over-year annual revenue growth rate	44.00%
Percentage of targeted financial performance						150.00%	25.00%
Unrecognized compensation expense related to restricted stock awards						$ 1.5
Weighted average remaining contractual terms						1 year 9 months 18 days
Minimum | Scenario Performance Financial Metric Less Than 50%
Weighted Average Grant Date Fair Value [Roll Forward]
Percentage of targeted financial performance		50.00%
Minimum | Scenario Performance Financial Metric is Between 50% to 200%
Weighted Average Grant Date Fair Value [Roll Forward]
Percentage of targeted financial performance		50.00%
Maximum | Scenario Performance Financial Metric is Between 50% to 200%
Weighted Average Grant Date Fair Value [Roll Forward]
Percentage of targeted financial performance		200.00%
Maximum | Scenario Performance Financial Metric Greater Than 200%
Weighted Average Grant Date Fair Value [Roll Forward]
Percentage of targeted financial performance		200.00%
First Anniversary
Shares [Roll Forward]
Vested (in shares)						0
Weighted Average Grant Date Fair Value [Roll Forward]
Vesting period						4 years
Chief Executive Officer
Weighted Average Grant Date Fair Value [Roll Forward]
Stock options grants in period			113,130
Chief Executive Officer | Scenario Performance Financial Metric Less Than 50%
Weighted Average Grant Date Fair Value [Roll Forward]
Stock options grants in period		114,320
Chief Executive Officer | Scenario Performance Financial Metric is Between 50% to 200%
Weighted Average Grant Date Fair Value [Roll Forward]
Stock options grants in period		114,320
Chief Executive Officer | Scenario Performance Financial Metric Greater Than 200%
Weighted Average Grant Date Fair Value [Roll Forward]
Stock options grants in period		114,320
Chief Financial Officer
Weighted Average Grant Date Fair Value [Roll Forward]
Stock options grants in period			38,475
Chief Financial Officer | Scenario Performance Financial Metric Less Than 50%
Weighted Average Grant Date Fair Value [Roll Forward]
Stock options grants in period		32,100
Chief Financial Officer | Scenario Performance Financial Metric is Between 50% to 200%
Weighted Average Grant Date Fair Value [Roll Forward]
Stock options grants in period		32,100
Chief Financial Officer | Scenario Performance Financial Metric Greater Than 200%
Weighted Average Grant Date Fair Value [Roll Forward]
Stock options grants in period		32,100

Net Income (Loss) Per Share (De

Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Numerator:
Net income attributable to AXT, Inc.	$ 3,165	$ 3,425
Less: Preferred stock dividends	(44)	(44)
Net income available to common stockholders	$ 3,121	$ 3,381
Weighted-average number of common shares outstanding:
Denominator for basic net income (loss) per share - weighted-average common shares	41,871,000	41,004,000
Effect of dilutive securities:
Denominator for dilutive net income per common shares	42,662,000	42,726,000
Net income attributable to AXT,Inc. per common share:
Basic	$ 0.07	$ 0.08
Diluted	$ 0.07	$ 0.08
Preferred stock, shares issued (in shares)	883,000		883,000
Preferred stock, shares outstanding (in shares)	883,000		883,000
Preferred stock, par value (in dollars per share)	$ 0.001		$ 0.001
Preferred stock, value	$ 3,532		$ 3,532
Cumulative annual dividend rate (as a percent)	5.00%		5.00%
Liquidation preference over common stock (in dollars per share)	$ 4		$ 4
Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from diluted net income (loss) per share as the impact is anti-dilutive (in shares)	201,000	21,000
Restricted Stock Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from diluted net income (loss) per share as the impact is anti-dilutive (in shares)	218,000	57,000
Options [Member]
Effect of dilutive securities:
Effect of dilutive securities (in shares)	474,000	1,082,000
Restricted Stock Awards [Member]
Effect of dilutive securities:
Effect of dilutive securities (in shares)	317,000	640,000

Segment Information and Forei_3

Segment Information and Foreign Operations - Product Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenue by product type
Revenue	$ 39,653	$ 31,350
Substrates
Revenue by product type
Revenue	31,745	23,373
Raw Materials And Others
Revenue by product type
Revenue	$ 7,908	$ 7,977

Segment Information and Forei_4

Segment Information and Foreign Operations - Segment and Geographical Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)segment	Mar. 31, 2021USD ($)	Dec. 31, 2021USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of operating segments | segment	1
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	$ 39,653	$ 31,350
Long-lived assets by geographic region, net of depreciation:
Long-lived assets	149,509		$ 144,739
Reportable Geographical Components | China
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	17,480	15,546
Long-lived assets by geographic region, net of depreciation:
Long-lived assets	148,612		143,129
Reportable Geographical Components | Taiwan
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	6,859	3,015
Reportable Geographical Components | Japan
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	2,807	2,523
Reportable Geographical Components | Asia Pacific (excluding China, Taiwan, and Japan)
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	1,756	1,817
Reportable Geographical Components | Europe
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	6,394	5,435
Reportable Geographical Components | North America
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	4,357	$ 3,014
Long-lived assets by geographic region, net of depreciation:
Long-lived assets	$ 897		$ 1,610

Segment Information and Forei_5

Segment Information and Foreign Operations - Concentration of Credit Risk (Details) - Customer concentration - customer	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Revenue [Member]
Revenue, Major Customer [Line Items]
Number of customers representing significant share		0
Accounts Receivable
Revenue, Major Customer [Line Items]
Number of customers representing significant share	2		0
Landmark [Member] | Revenue [Member]
Revenue, Major Customer [Line Items]
Number of customers representing significant share	1
Percentage share generated by major customers	10.00%
Major Customer One | Accounts Receivable
Revenue, Major Customer [Line Items]
Percentage share generated by major customers	12.00%
Major Customer Two | Accounts Receivable
Revenue, Major Customer [Line Items]
Percentage share generated by major customers	10.00%
Top Five Major Customers | Revenue [Member]
Revenue, Major Customer [Line Items]
Number of customers representing significant share	5	5
Percentage share generated by major customers	29.00%	26.00%

Commitments and Contingencies_2

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Product Warranty [Abstract]
Period of warranty	12 months
Change in warranty accrual [Roll Forward]
Beginning accrued product warranty	$ 743	$ 609
Accruals for warranties issued	556	113
Adjustments related to pre-existing warranties including expirations and changes in estimates	(113)	(54)
Cost of warranty repair	(354)	(86)
Ending accrued product warranty	$ 832	$ 582
Cross License Agreement
Preferred label sub abstract as Contractual Obligations
Term of agreement	10 years
Dingxing
Preferred label sub abstract as Contractual Obligations
Total investment agreement value	$ 90,000
Kazuo
Preferred label sub abstract as Contractual Obligations
Total investment agreement value	15,000
Kazuo | Beijing BoYu Semiconductor Vessel Craftwork Technology Co
Preferred label sub abstract as Contractual Obligations
Total investment agreement value	$ 8,000

Other Expense, Net (Details)

Other Expense, Net (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Other Expense, Net
Income from government grants	$ 200,000	$ 100,000
Foreign exchange loss	$ 228,000	$ 173,000

Income Taxes - (Details)

Income Taxes - (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)
Income Taxes
Unrecognized tax benefit interest and penalties expense	$ 0
Unrecognized tax benefits accrued interest and penalties	$ 0

Revenue - Contract Balances (De

Revenue - Contract Balances (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Revenue
Contract liabilities	$ 1,024,000	$ 946,000
Revenue recognized, included in contract balances	$ 321,000

Revenue - Disaggregated Revenue

Revenue - Disaggregated Revenue (Details)	3 Months Ended
	Mar. 31, 2022segment
Disaggregation of Revenue [Line Items]
Number of operating segments	1
Maximum
Disaggregation of Revenue [Line Items]
Sales commissions benefit period	1 year

Bank Loans and Line of Credit (

Bank Loans and Line of Credit (Details) - USD ($) $ in Thousands	Sep. 12, 2019	Aug. 09, 2019	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Apr. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Aug. 31, 2020	Mar. 31, 2020	Feb. 29, 2020	Dec. 31, 2019	Jan. 31, 2022	Nov. 30, 2021	Jun. 30, 2021	Oct. 31, 2020
Bank Of China | Beijing Tongmei Xtal Technology | Lines OF Credit, Current
Debt Instrument [Line Items]
Letters of credit outstanding			$ 0
Combined loans renewed			0
Bank Of China | Secured Debt | Lines OF Credit, Current
Debt Instrument [Line Items]
Letters of credit outstanding			4,400
Combined loans renewed			4,400
Bank Of China | Secured Debt | Beijing Tongmei Xtal Technology
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 5,800	3,100					$ 3,100					$ 4,400
Repayments of line of credit			$ 2,700		$ 3,100	$ 5,600
Letters of credit outstanding					2,700										$ 5,800
Proceeds from credit facility	$ 2,800	$ 2,800
Combined loans renewed					$ 2,700										$ 5,800
Interest rate			3.70%		3.85%			3.85%					4.55%		4.70%	4.70%
Combined loan totals																$ 5,600
Renewal period								6 months
Additional loan borrowed																$ 2,700
Repayments of loan									$ 5,900
Bank Of China | Secured Debt | Beijing Tongmei Xtal Technology | Lines OF Credit, Current
Debt Instrument [Line Items]
Letters of credit outstanding			$ 3,100
Combined loans renewed			3,100
Bank Of China | Secured Debt | Beijing Tongmei Xtal Technology | Prime Rate
Debt Instrument [Line Items]
Variable rate spread (as a percent)		0.40%										4.70%
ICBC | Secured Debt | Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd Investment
Debt Instrument [Line Items]
Maximum borrowing capacity											$ 1,400
Annual interest rate at end							4.30%
Repayments of line of credit				$ 1,600			$ 400
Letters of credit outstanding				1,600			1,500
Proceeds from lines of credit										$ 400
Combined loans renewed				$ 1,600			$ 1,500
Interest rate				3.92%
ICBC | Secured Debt | Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd Investment | Lines OF Credit, Current
Debt Instrument [Line Items]
Letters of credit outstanding			1,600
Combined loans renewed			1,600
ICBC | Secured Debt | Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd Investment | Prime Rate
Debt Instrument [Line Items]
Variable rate spread (as a percent)							0.07%				0.15%
Bank of Communications | Secured Debt | Lines OF Credit, Current
Debt Instrument [Line Items]
Letters of credit outstanding			1,600
Combined loans renewed			1,600
Bank of Communications | Secured Debt | Beijing Tongmei Xtal Technology
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 3,100								$ 1,600	$ 1,600
Letters of credit outstanding														4,700
Combined loans renewed														$ 4,700
Interest rate					4.00%								3.30%
Bank of Communications | Secured Debt | Beijing Tongmei Xtal Technology | Lines OF Credit, Current
Debt Instrument [Line Items]
Letters of credit outstanding			4,700
Combined loans renewed			4,700
Bank of Communications | Secured Debt | Nanjing JinMei Gallium Co., Ltd Investment
Debt Instrument [Line Items]
Maximum borrowing capacity													$ 1,600
Interest rate													3.30%
Bank of Communications | Secured Debt | Nanjing JinMei Gallium Co., Ltd Investment | Lines OF Credit, Current
Debt Instrument [Line Items]
Letters of credit outstanding			1,600
Combined loans renewed			1,600
China Merchants Bank | Secured Debt | Lines OF Credit, Current
Debt Instrument [Line Items]
Letters of credit outstanding			1,600
Combined loans renewed			1,600
China Merchants Bank | Secured Debt | Beijing Tongmei Xtal Technology
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 1,600
Interest rate				3.55%
Guarantee fee (as a percent)				1.50%
Amount of guarantee fee				$ 24
China Merchants Bank | Unsecured Debt | Beijing Tongmei Xtal Technology
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 1,600
Interest rate				4.22%
China Merchants Bank | Unsecured Debt | Beijing Tongmei Xtal Technology | Lines OF Credit, Current
Debt Instrument [Line Items]
Letters of credit outstanding			1,600
Combined loans renewed			$ 1,600

Leases (Details)

Leases (Details) $ in Millions	1 Months Ended	3 Months Ended
	May 31, 2020	Mar. 31, 2022USD ($)ft²
Leases
Area of leased property (in square feet) | ft²		19,467
Operating lease, option to extend	true
Operating lease, extension term	3 years
Variable lease payments		$ 0
Residual value guarantee		$ 0

Leases - Maturities of Operatin

Leases - Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Future minimum lease payments
2022	$ 444
2023	582
2024	293
2025	293
2026	293
Thereafter	757
Total minimum lease payments	2,662
Less: Interest	(353)
Present value of lease obligations	2,309
Less: Current portion, included in accrued liabilities	$ (499)	$ (488)
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accrued Liabilities, Current
Long-term portion of lease obligations	$ 1,810	$ 1,935

Leases - Weighted-Average Remai

Leases - Weighted-Average Remaining Lease Term and Discount Rate (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Leases
Weighted-average remaining lease term (years)	6 years 3 months 14 days		6 years 5 months 8 days
Weighted-average discount rate	4.61%		4.61%
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 147	$ 141

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Lease expense
Operating lease	$ 134	$ 133
Short-term lease expense	36	24
Total	$ 170	$ 157

Redeemable Noncontrolling Int_3

Redeemable Noncontrolling Interests (Details) - Beijing Tongmei Xtal Technology - USD ($) $ in Millions	Jan. 25, 2021	Jan. 31, 2021	Mar. 31, 2022	Dec. 31, 2020
Noncontrolling Interest [Line Items]
Issue of redeemable noncontrolling interests		$ 1.5		$ 48.1
Redeemable noncontrolling interests ownership percentage				7.06%
Investments, government approved	$ 49
Percentage of equity issued on conversion of noncontrolling interests	7.28%		14.50%
Redemption value			$ 49

Redeemable Noncontrolling Int_4

Redeemable Noncontrolling Interests - Components of the Change in Redeemable Noncontrolling Interests (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)
Redeemable Noncontrolling Interests
Redeemable noncontrolling interests beginning balance	$ 50,385
Investment in subsidiary with redeemable noncontrolling interest	206
Equity issuance costs incurred	(227)
Stock-based compensation attributable to redeemable noncontrolling interests	(6)
Net income attributable to redeemable noncontrolling interests	418
Effect of foreign currency translation on redeemable noncontrolling interests	149
Effect of foreign currency translation attributable to redeemable noncontrolling interests	46
Redeemable noncontrolling interests ending balance	$ 50,971

Subsequent Event (Details)

Subsequent Event (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended
	Apr. 30, 2022	Jan. 31, 2022	Mar. 31, 2022	Mar. 31, 2021
Subsequent Event
Investment in subsidiary with noncontrolling interest			$ 206	$ 576
Loan from related party | Beijing Tongmei Xtal Technology | ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd
Subsequent Event
Increase in noncontrolling interest		$ 2,200
Increase in redeemable noncontrolling interests		$ 200
Percentage of ownership, equity method		58.50%
Subsequent Event | Loan from related party | ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd
Subsequent Event
Investment in subsidiary with noncontrolling interest	$ 4,500
Increase in redeemable noncontrolling interests	100
Subsequent Event | Loan from related party | Beijing Tongmei Xtal Technology | ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd
Subsequent Event
Amount paid to subsidiary	1,100
Investment in subsidiary with noncontrolling interest	2,600
Increase in noncontrolling interest	$ 800
Percentage of ownership, equity method	58.50%
Subsequent Event | Loan from related party | ChaoYang Xinshuo | ChaoYang XinMei High Purity Semiconductor Materials Co., Ltd
Subsequent Event
Amount paid to subsidiary	$ 700
Investment in subsidiary with noncontrolling interest	$ 1,900