AXT (AXTI) 10-Q 6 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 01, 2020
Document And Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
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	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		41,300,000
Entity Central Index Key	0001051627
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 22,384	$ 26,892
Short-term investments	4,505	9,427
Accounts receivable, net of allowances of $121 and $34 as of September 30, 2020 and December 31, 2019	22,653	19,031
Inventories	48,357	49,152
Prepaid expenses and other current assets	10,649	8,703
Total current assets	108,548	113,205
Long-term investments	2,884
Property, plant and equipment, net	108,295	97,403
Operating lease right-of-use assets	2,702	2,938
Other assets	10,308	9,803
Total assets	232,737	223,349
Current liabilities:
Accounts payable	12,271	10,098
Accrued liabilities	10,842	11,681
Bank loan	3,380	5,747
Total current liabilities	26,493	27,526
Long-term portion of royalty payments	1,193
Noncurrent operating lease liabilities	2,415	2,695
Other long-term liabilities	744	366
Total liabilities	30,845	30,587
Commitments and contingencies (Note 12)
Stockholders' equity:
Preferred stock Series A, $0.001 par value; 2,000 shares authorized; 883 shares issued and outstanding as of September 30, 2020 and December 31, 2019 (Liquidation preference of $7,301 and $7,169 as of September 30, 2020 and December 31, 2019)	3,532	3,532
Common stock, $0.001 par value; 70,000 shares authorized; 41,135 and 40,632 shares issued and outstanding as of September 30, 2020 and December 31, 2019	41	41
Additional paid-in capital	240,422	236,957
Accumulated deficit	(46,609)	(47,783)
Accumulated other comprehensive loss	(1,992)	(4,862)
Total AXT, Inc. stockholders' equity	195,394	187,885
Noncontrolling interests	6,498	4,877
Total stockholders' equity	201,892	192,762
Total liabilities and stockholders' equity	$ 232,737	$ 223,349

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Accounts receivable, allowances for doubtful accounts	$ 121	$ 34
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	$ 7,301	$ 7,169
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)	41,135,000	40,632,000
Common stock, shares outstanding (in shares)	41,135,000	40,632,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
Revenue	$ 25,469	$ 19,841	$ 68,326	$ 64,846
Cost of revenue	16,646	14,082	47,213	43,886
Gross profit	8,823	5,759	21,113	20,960
Operating expenses:
Selling, general and administrative	4,623	4,755	14,119	14,247
Research and development	2,023	1,482	4,973	4,227
Total operating expenses	6,646	6,237	19,092	18,474
Income (loss) from operations	2,177	(478)	2,021	2,486
Interest income (expense), net	(70)	41	(138)	215
Equity in income (loss) of unconsolidated joint ventures	45	(204)	(243)	(1,650)
Other income (expense), net	(34)	169	2,940	(55)
Income (loss) before provision for income taxes	2,118	(472)	4,580	996
Provision for income taxes	637	23	1,923	776
Net (loss) income	1,481	(495)	2,657	220
Less: Net income attributable to noncontrolling interests	(490)	(403)	(1,483)	(771)
Net income (loss) attributable to AXT, Inc.	$ 991	$ (898)	$ 1,174	$ (551)
Net income (loss) attributable to AXT, Inc. per common share:
Basic	$ 0.02	$ (0.02)	$ 0.03	$ (0.02)
Diluted	$ 0.02	$ (0.02)	$ 0.03	$ (0.02)
Weighted-average number of common shares outstanding:
Basic	40,152	39,466	39,978	39,438
Diluted	40,979	39,466	40,688	39,438

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income (loss)	$ 1,481	$ (495)	$ 2,657	$ 220
Other comprehensive income (loss), net of tax:
Change in foreign currency translation gain (loss), net of tax	4,699	(4,322)	3,086	(4,322)
Change in unrealized gain on available-for-sale debt investments, net of tax	(10)	(2)	11	78
Reclassification adjustment for gains included in net loss upon deconsolidation of a subsidiary				(617)
Total other comprehensive income (loss), net of tax	4,689	(4,324)	3,097	(4,861)
Comprehensive income (loss)	6,170	(4,819)	5,754	(4,641)
Less: Comprehensive income(loss) attributable to noncontrolling interests	(806)	(189)	(1,710)	(1,178)
Comprehensive income (loss) attributable to AXT, Inc.	$ 5,364	$ (5,008)	$ 4,044	$ (5,819)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income	$ 2,657	$ 220
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,963	4,173
Amortization of marketable securities premium	28	26
Impairment charge on equity investee		1,068
Stock-based compensation	1,932	1,709
Provision for doubtful accounts	87
Loss on disposal of equipment	36	43
Gain from deconsolidation of a subsidiary		(175)
Loss from equity method investments, net	243	757
Return on equity method investments		362
Changes in operating assets and liabilities:
Accounts receivable	(3,500)	1,876
Inventories	1,638	8,272
Prepaid expenses and other current assets	(1,790)	3,277
Other assets	(424)	(3,108)
Accounts payable	1,992	(4,993)
Accrued liabilities	(1,226)	(6,216)
Other long-term liabilities, including royalties	1,688	46
Net cash provided by operating activities	6,324	7,337
Cash flows from investing activities:
Purchases of property, plant and equipment	(12,121)	(13,969)
Purchases of available-for-sale debt securities	(2,880)	(8,725)
Proceeds from sales and maturities of available-for-sale debt securities	4,901	20,988
Net cash used in investing activities	(10,100)	(1,706)
Cash flows from financing activities:
Proceeds from common stock options exercised	1,137	267
Proceeds from sale of previously consolidated subsidiary shares		366
Consideration paid to repurchase subsidiary shares from noncontrolling interests		(262)
Payments on short-term loan	(5,801)
Proceeds from short-term loan	3,380	5,760
Proceeds from sale of subsidiary shares to noncontrolling interest	396
Dividends paid by joint ventures to their minority shareholders	(89)
Net cash provided by (used in) financing activities	(977)	6,131
Effect of exchange rate changes on cash and cash equivalents	245	(451)
Net increase (decrease) in cash and cash equivalents	(4,508)	11,311
Cash and cash equivalents at the beginning of the year	26,892	16,526
Cash and cash equivalents at the end of the year	$ 22,384	27,837
Supplemental disclosure of non-cash flow information:
Consideration payable to repurchase subsidiary shares from noncontrolling interests, included in accrued liabilities		151
Reduction of noncontrolling interests in excess (deficit) of total consideration paid and payable in connection with the repurchase of subsidiary shares from noncontrolling interests		$ (74)

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2020
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 and nine months ended September 30, 2020 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 2019 Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on March 12, 2020 and our Quarterly Report on Form 10-Q for the three months ended March 31, 2020 and June 30, 2020 filed with the SEC on May 8, 2020 and August 7, 2020, respectively. ​ The condensed consolidated financial statements include the accounts of AXT, our wholly-owned subsidiaries, Beijing Tongmei Xtal Technology Co., Ltd. (“Tongmei”), Baoding Tongmei Xtal Technology Co., Ltd. (“Tongmei Baoding”), ChaoYang Tongmei Xtal Technology Co., Ltd. (“Tongmei ChaoYang”), and ChaoYang LiMei Semiconductor Technology Co., Ltd. (“LiMei ChaoYang”), and, except as discussed below and in Note 7, our majority-owned subsidiaries, Nanjing JinMei Gallium Co., Ltd. (“JinMei”), ChaoYang JinMei Gallium Ltd., MaAnShan JinMei Gallium Ltd., and Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd. (“BoYu”). Tongmei Baoding is located in the city of Dingxing, China. Each of Tongmei ChaoYang and LiMei ChaoYang is located in the city of Kazuo, China. 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 September 30, 2020 and December 31, 2019, 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 noncontrolling interests on our condensed consolidated balance sheets in stockholders' equity and in our condensed consolidated statements of operations. ​ When market conditions are warranted, we intend to construct facilities at the LiMei ChaoYang location to provide us with additional production capacity. For the three and nine months ended September 30, 2020, expenses associated with LiMei ChaoYang had a de minimis impact on our condensed consolidated financial statements. ​ As discussed in Note 7, “Investments in Privately-Held Companies”, effective as of March 11, 2019 we reduced our ownership in Beijing JiYa Semiconductor Material Co., Ltd. (“JiYa”) from 46% to 39% by selling a portion of our JiYa shares to our investor partner, which is also JiYa’s landlord. As a result of this transaction, our investor partner became the largest shareholder of JiYa and assumed the right to appoint the general manager of JiYa and thereby exercised greater control over JiYa’s long-term strategic direction. Further, although our Chief Executive Officer remains on the board, as of March 11, 2019, he was no longer the chairman of JiYa’s board of directors and our Chief Financial Officer was no longer a member of JiYa’s board of financial supervisors. Therefore, we deconsolidated JiYa from our consolidated financial statements as of March 11, 2019 in accordance with Accounting Standards Codification (“ASC”) Topic 810 Consolidation (“ASC 810”). As of March 12, 2019, we accounted for our retained investment in JiYa under the equity method of accounting, as we continue to exercise significant influence. ​ Our condensed consolidated balance sheet as of December 31, 2019, as reported, does not include the assets and liabilities of JiYa since we deconsolidated JiYa as of March 11, 2019. Our unaudited condensed consolidated statement of operations for the nine months ended September 30, 2019 includes JiYa’s results for the period through March 11, 2019. ​ As discussed in Note 7, in May 2019, we purchased the remaining 3% ownership interest of JinMei that we did not own from retiring members of the JinMei management team for approximately $413,000. As a result, our ownership of JinMei increased from 97% to 100%. As of June 1, 2019, we referred to JinMei as a wholly-owned subsidiary instead of a significantly controlled 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.

Investments and Fair Value Meas

Investments and Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
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 September 30, 2020 and December 31, 2019, our cash, cash equivalents and debt investments are classified as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2020 ​ December 31, 2019 ​ ​ ​ Gross Gross ​ ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Cost Gain (Loss) Value Cost Gain (Loss) Value Classified as: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash ​ $ 22,384 ​ $ — ​ $ — ​ $ 22,384 ​ $ 26,892 ​ $ — ​ $ — ​ $ 26,892 ​ Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit 1 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Total cash and cash equivalents ​ 22,384 ​ — ​ — ​ 22,384 ​ 26,892 ​ — ​ — ​ 26,892 ​ Investments (available-for-sale): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit 2 ​ 2,880 ​ 4 ​ ​ — ​ 2,884 ​ 2,400 ​ 2 ​ ​ — ​ 2,402 ​ Corporate bonds ​ 4,501 ​ 4 ​ — ​ 4,505 ​ 7,030 ​ 4 ​ (9) ​ 7,025 ​ Total investments ​ 7,381 ​ 8 ​ — ​ 7,389 ​ 9,430 ​ 6 ​ (9) ​ 9,427 ​ Total cash, cash equivalents and investments ​ $ 29,765 ​ $ 8 ​ $ — ​ $ 29,773 ​ $ 36,322 ​ $ 6 ​ $ (9) ​ $ 36,319 ​ Contractual maturities on investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Due within 1 year 3 ​ $ 4,501 ​ ​ ​ ​ ​ ​ ​ $ 4,505 ​ $ 9,430 ​ ​ ​ ​ ​ ​ ​ $ 9,427 ​ Due after 1 through 5 years 4 ​ 2,880 ​ ​ ​ ​ ​ ​ ​ 2,884 ​ — ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ $ 7,381 ​ ​ ​ ​ ​ ​ ​ $ 7,389 ​ $ 9,430 ​ ​ ​ ​ ​ ​ ​ $ 9,427 ​ 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 were no gross unrealized losses on our available-for-sale debt securities as of September 30, 2020, 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. ​ None of our debt investments would generate a loss if we sold them on September 30, 2020. ​ 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, 2019 (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, 2019 ​ Value ​ (Loss) ​ Value ​ (Loss) ​ Value ​ (Loss) Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds ​ 4,515 ​ (9) ​ — ​ — ​ 4,515 ​ ​ (9) ​ Total in loss position ​ $ 4,515 ​ $ (9) ​ $ — ​ $ — ​ $ 4,515 ​ $ (9) ​ ​ 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 $5.8 million and $6.0 million as of September 30, 2020 and December 31, 2019, respectively. As of September 30, 2020, there were five companies accounted for under the equity method. There were no impairment charges in the three and nine months ended September 30, 2020. The nine months ended September 30, 2019 include an impairment charge of $1.1 million for one of our minority investments (see Note 7). There were no impairment charges in the three months ended September 30, 2019. ​ 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 September 30, 2020 and December 31, 2019, the total unrealized loss, net of tax, included in accumulated other comprehensive loss 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. ASC Topic 820, Fair Value Measurements and Disclosures we measure certain financial assets and liabilities at fair value, primarily consisting of our short-term and long-term debt investments. ​ 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 September 30, 2020, 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 and nine months ended September 30, 2020. There have been no transfers between fair value measurements levels during the three and nine months ended September 30, 2020. ​ The following table summarizes our financial assets and liabilities measured at fair value on a recurring basis in accordance with ASC 820 as of September 30, 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices in ​ ​ ​ Significant ​ ​ ​ ​ ​ Active Markets of ​ Significant Other ​ Unobservable ​ ​ Balance as of ​ Identical Assets ​ Observable Inputs ​ Inputs ​ September 30, 2020 (Level 1) (Level 2) (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents and investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ $ 2,884 ​ $ — ​ $ 2,884 ​ $ — ​ Corporate bonds ​ 4,505 ​ — ​ 4,505 ​ — ​ Total ​ $ 7,389 ​ $ — ​ $ 7,389 ​ $ — ​ ​ 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, 2019 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices in ​ ​ ​ Significant ​ ​ ​ ​ ​ Active Markets of ​ Significant Other ​ Unobservable ​ ​ Balance as of ​ Identical Assets ​ Observable Inputs ​ Inputs ​ December 31, 2019 (Level 1) (Level 2) (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents and investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ $ 2,402 ​ $ — ​ $ 2,402 ​ $ — ​ Corporate bonds ​ 7,025 ​ — ​ 7,025 ​ — ​ Total ​ $ 9,427 ​ $ — ​ $ 9,427 ​ $ — ​ ​ 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). One such investment is a 25 % ownership interest in a germanium materials company in China. After receiving such company’s preliminary first quarter 2019 financial results in early April 2019 and its projections for significant losses going forward, we determined that this asset was fully impaired and wrote the asset balance down to zero . This resulted in a $1.1 million impairment charge in our first quarter 2019 financial results. Except as mentioned above, we did not record other-than-temporary impairment charges for the remainder of these investments during the three and nine months ended September 30, 2020 and 2019, respectively.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2020
Inventories
Inventories	Note 3. Inventories ​ The components of inventories are summarized below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2020 2019 Inventories: ​ ​ ​ ​ ​ ​ ​ Raw materials ​ $ 23,078 ​ $ 20,677 ​ Work in process ​ 23,166 ​ 24,946 ​ Finished goods ​ 2,113 ​ 3,529 ​ ​ ​ $ 48,357 ​ $ 49,152 ​ ​ As of September 30, 2020 and December 31, 2019, carrying values of inventories were net of inventory reserves of $16.9 million and $16.4 million, respectively, for excess and obsolete inventory and $86,000 and $91,000, respectively, for lower of cost or net realizable value reserves.

Property, Plant and Equipment,

Property, Plant and Equipment, Net	9 Months Ended
	Sep. 30, 2020
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): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ 2020 ​ 2019 ​ Property, plant and equipment: ​ ​ ​ ​ ​ ​ ​ Machinery and equipment, at cost ​ $ 46,207 ​ $ 45,742 ​ Less: accumulated depreciation and amortization ​ ​ (37,876) ​ ​ (37,115) ​ Building, at cost ​ ​ 39,870 ​ ​ 38,837 ​ Less: accumulated depreciation and amortization ​ ​ (14,070) ​ ​ (12,736) ​ Leasehold improvements, at cost ​ 5,903 ​ 4,877 ​ Less: accumulated depreciation and amortization ​ ​ (4,404) ​ ​ (4,035) ​ Construction in progress ​ 72,665 ​ 61,833 ​ ​ ​ $ 108,295 ​ $ 97,403 ​ ​ As of September 30, 2020, the balance of construction in progress was $72.7 million, of which $57.8 million was related to our buildings in our new Dingxing and Kazuo locations, $4.2 million was for manufacturing equipment purchases not yet placed in service and $10.7 million was for our construction in progress for our other consolidated subsidiaries. As of December 31, 2019, the balance of construction in progress was $61.8 million, of which $48.8 million was for our buildings in our new Dingxing and Kazuo locations, $3.4 million was for manufacturing equipment purchases not yet placed in service and $9.6 million was for our construction in progress at our other consolidated subsidiaries. ​ From time to time we review our estimates of the useful lives of our property, plant and equipment. As a result of the review, we determined a portion of our manufacturing equipment was lasting longer than the estimate previously established for the respective useful lives. Where appropriate, we extended the useful life of the manufacturing equipment in our accounting records. In addition, the useful life of our buildings located in China was extended to better align with industry standards. The changes in our estimate of the useful life, effective January 1, 2020, were made in order to remain consistent with US GAAP regarding management estimates. The effect of the change in the useful lives decreased our manufacturing costs for the three and nine months ended September 30, 2020 by approximately $0.3 million and $0.9 million, respectively, and increased our basic and diluted net income per share by approximately $0.01 and $0.03, respectively, as a result of lower depreciation expense.

Accrued Liabilities

Accrued Liabilities	9 Months Ended
	Sep. 30, 2020
Accrued Liabilities
Accrued Liabilities	Note 5. Accrued Liabilities ​ The components of accrued liabilities are summarized below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2020 2019 Preferred stock dividends payable ​ $ 2,901 ​ $ 2,901 ​ Accrued compensation and related charges ​ ​ 2,213 ​ ​ 3,307 ​ Payable in connection with land restoration of Nanjing JinMei factory ​ ​ 720 ​ ​ 703 ​ Accrued income taxes ​ ​ 714 ​ ​ 171 ​ Accrued professional services ​ ​ 659 ​ ​ 630 ​ Accrued product warranty ​ ​ 529 ​ ​ 387 ​ Advance from customers ​ ​ 494 ​ ​ 396 ​ Current portion of operating lease liabilities ​ ​ 421 ​ ​ 319 ​ Other tax payable ​ ​ 357 ​ ​ 50 ​ Current portion of royalty payments ​ ​ 300 ​ ​ — ​ Payable in connection with construction ​ ​ 208 ​ ​ 1,447 ​ Other personnel-related costs ​ ​ 142 ​ ​ 180 ​ Accrual for sales returns ​ ​ 92 ​ ​ 26 ​ Payable in connection with repurchase of subsidiaries shares ​ ​ 49 ​ ​ 151 ​ Other accrued liabilities ​ ​ 1,043 ​ ​ 1,013 ​ ​ ​ $ 10,842 ​ $ 11,681 ​ ​

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2020
Related Party Transactions
Related Party Transactions	Note 6. Related Party Transactions ​ Effective as of March 11, 2019, we reduced our ownership in JiYa from 46% to 39% by selling a portion of our JiYa shares to our investor partner, which is also JiYa’s landlord. Based on an independent third party valuation analysis, we sold these shares for $366,000 . Previously, we were the largest shareholder of JiYa and as such, we had the right to appoint the general manager of JiYa and the ability to exercise control in substance over JiYa’s long-term strategic direction. Further, our Chief Executive Officer was the chairman of JiYa’s board of directors and our Chief Financial Officer was a member of JiYa’s board of financial supervisors. As a result of this transaction, our investor partner, Shanxi Aluminum Industrial Co., Ltd. became the largest shareholder of JiYa and assumed the right to appoint the general manager of JiYa and thereby exercised greater control over JiYa’s long-term strategic direction. Further, although our Chief Executive Officer remains on the board, as of March 11, 2019, he was no longer chairman of JiYa’s board of directors and our Chief Financial Officer was no longer on JiYa’s board of financial supervisors. ​ Previously, we accounted for JiYa’s financial performance under the consolidation method of accounting. As a result of the changes, we began to account for JiYa’s financial performance under the equity method of accounting. Therefore, we deconsolidated JiYa from our consolidated financial statements as of March 11, 2019 in accordance with ASC 810. As of March 12, 2019, we accounted for our investment in JiYa under the equity method of accounting as we continue to have board representation and substantial ownership. ​ Beginning in 2012, our consolidated joint venture, JinMei, became contractually obligated under an agency sales agreement to sell raw material on behalf of its equity investment entity. JinMei bills the customers and remits the receipts, net of its portions of sales commission, to this equity investment entity. For the three months ended September 30, 2020 and 2019, JinMei has recorded $0 and $0 income from agency sales, respectively. For the nine months ended September 30, 2020 and 2019, JinMei has recorded $0 and $0 income from agency sales, respectively, which were included in “Other income (expense), net” in the condensed consolidated statements of operations. ​ In March 2012, Tongmei, entered into an operating lease for the land it owns with our consolidated joint venture, 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 ​ Tongmei ChaoYang 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 September 30, 2020 and December 31, 2019, amounts payable of $163,000 and $0 , respectively, were included in “Accounts payable” in our condensed consolidated balance sheets. ​ Tongmei ChaoYang also purchases raw materials from one of our equity investment entities, Emei Shan Jiamei Materials Co., Ltd. (“JiaMei”), for production in the ordinary course of business. As of September 30, 2020 and December 31, 2019, amounts payable of $0 and $0 , respectively, were included in “Accounts payable” in our condensed consolidated balance sheets. ​ Tongmei and Tongmei ChaoYang also purchase raw materials from one of our equity investment entities, Xilingol Tongli Germanium Refine Co., Ltd. (“Tongli”), for production in the ordinary course of business. As of September 30, 2020 and December 31, 2019, amounts payable of $0 and $0 , 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 April 2016, our consolidated joint venture, BoYu, provided a personal loan of $177,000 to one of its executive employees. This loan is secured by the officer’s shares in BoYu. The loan bears interest at 2.75% per annum. During the three months ended June 30, 2017, the repayment of the principal and interest totaling $180,000 was received by our consolidated joint venture. and December 31, 2019 both principal and accrued interest, were $618,000 and $449,000 , respectively, and included in “Other assets” in our condensed consolidated balance sheets. ​ On November 2, 2017, our consolidated joint venture, 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. This third-party investor is an immediate family member of the owner of one of BoYu's customers. For the three months ended September 30, 2020 and 2019, BoYu has recorded $37,000 and $0, respectively, in revenue from this customer. For the nine months ended September 30, 2020 and 2019, BoYu has recorded $0.3 million and $0.1 million, respectively, in revenue from this customer. As of September 30, 2020 and December 31, 2019, amounts receivable of ​ 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	9 Months Ended
	Sep. 30, 2020
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. ​ As of September 30, 2020, the investments are summarized below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Investment Balance as of ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ Accounting ​ Ownership ​ Company 2020 2019 Method Percentage ​ Nanjing JinMei Gallium Co., Ltd. ​ $ 592 ​ $ 592 Consolidated **100 % Chaoyang JinMei Gallium Co., Ltd. ​ $ 1,820 ​ $ 1,820 ​ Consolidated ​ ***91.5 % Beijing JiYa Semiconductor Material Co., Ltd. ​ ​ N/A ​ ​ N/A ​ Consolidated ​ *46 % Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd. ​ 1,346 ​ 1,346 Consolidated 63 % ​ ​ $ 3,758 ​ $ 3,758 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Donghai County Dongfang High Purity Electronic Materials Co., Ltd. ​ $ 1,509 ​ $ 1,326 Equity 46 % Beijing JiYa Semiconductor Material Co., Ltd. ​ ​ 1,192 ​ ​ 1,621 ​ Equity ​ *39 % Xilingol Tongli Germanium Co., Ltd. ​ — ​ — Equity 25 % Xiaoyi XingAn Gallium Co., Ltd. ​ ​ 2,605 ​ ​ 2,367 ​ Equity ​ 25 % Emeishan Jia Mei High Purity Metals Co., Ltd. ​ 520 ​ 647 Equity 25 % ​ ​ $ 5,826 ​ $ 5,961 ​ ​ ​ ​ ​ ​ * Ownership percentage decreased from 46% to 39% as of March 11, 2019 in connection with our sale of shares of this entity. ** In May 2019, we purchased the remaining 3% ownership interest that we did not own from retiring members of the JinMei management team for approximately $413,000. As a result, our ownership of JinMei increased from 97% to 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%. ​ Effective as of March 11, 2019, we reduced our ownership in JiYa from 46% to 39 % by selling a portion of our JiYa shares to our investor partner, which is also JiYa’s landlord. Based on an independent third party valuation analysis, we sold these shares for $366,000 . Previously, we were the largest shareholder and, as such, we had the right to appoint the general manager of JiYa and the ability to exercise control in substance over JiYa’s long-term strategic direction. Further, our Chief Executive Officer was the chairman of JiYa’s board of directors and our Chief Financial Officer was a member of JiYa’s board of financial supervisors. As a result of this transaction, our investor partner, Shanxi Aluminum Industrial Co., Ltd., became the largest shareholder and assumed the right to appoint the general manager and thereby exercised greater control over JiYa’s long-term strategic direction. Further, although our Chief Executive Officer remains on the board, as of March 11, 2019 he was no longer the chairman of JiYa’s board of directors and our Chief Financial Officer was no longer a member of JiYa’s board of financial supervisors. ​ Previously, we accounted for JiYa’s financial performance under the consolidation method of accounting. As a result of the changes we began to account for JiYa’s financial performance under the equity method of accounting. Therefore, we deconsolidated JiYa from our consolidated financial statements as of March 11, 2019 in accordance with ASC 810. As of March 12, 2019, we accounted for our investment in JiYa under the equity method of accounting as we continue to have board representation and substantial ownership. periods presented. JiYa continues to be a related party to us after deconsolidation, whom we may purchase raw materials from for production in the ordinary course of business from time to time. ​ We recorded a gain on the deconsolidation of JiYa of $175,000 as a component of “Equity in loss of unconsolidated joint ventures” for the three months ended March 31, 2019 in the condensed consolidated statement of operations and comprehensive income (loss). On the date of deconsolidation, the fair value of the Company’s investment in JiYa exceeded the Company’s share of the net assets of JiYa, which generated the gain. As of March 12, 2019, we recorded our investment in JiYa at a fair value of $2,040,000, which was based on an independent third party valuation analysis. The valuation is based on the asset-based approach. The market-based approach is not deemed appropriate due to lack of availability of market data for comparable companies on the open market and the discounted cash flow approach is not deemed reliable because of the difficulty in predicting the future profitability of JiYa due to the volatility of the gallium market, the concentration of customers and the significant accumulated losses of JiYa. The asset-based approach examines the value of a company’s assets net of its liabilities to derive a value for the equity holders. The gain on deconsolidation includes the following: ​ ​ ​ ​ ​ ​ ​ Amount ​ (in thousands) Fair value of the consideration received ​ $ 366 Fair value of the retained investment in Beijing JiYa Semiconductor Material Co., Ltd. ​ ​ 2,040 Carrying value of noncontrolling interests, net of accumulated other comprehensive income attributable to subsidiary ​ ​ 617 Derecognition of Beijing JiYa Semiconductor Material Co., Ltd.'s net asset ​ ​ (2,848) Gain recognized on deconsolidation of Beijing JiYa Semiconductor Material Co., Ltd. ​ $ 175 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount ​ ​ (in thousands) Fair value of the retained investment in Beijing JiYa Semiconductor Material Co., Ltd. ​ $ 2,040 Carrying value of retained noncontrolling investment ​ ​ (1,559) Gain on retained noncontrolling investment due to remeasurement ​ $ 481 ​ ​ 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. ​ Our ownership of BoYu is 63%. 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%. 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. ​ 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. ​ During the three months ended September 30, 2020 and 2019, the consolidated joint ventures, before eliminating inter-company transactions, generated income of $1.8 million and $1.1 million, respectively, of which gains of $0.5 million and $0.4 million, respectively, were allocated to noncontrolling interests, resulting in an increase of $1.3 million to our net income and a reduction to our net loss of $0.7 million, respectively. During the nine months ended September 30, 2020 and 2019, the consolidated joint ventures, before eliminating inter-company transactions, generated income of $4.3 million and $2.6 million, respectively, of which gains of $1.5 million and $0.8 million, respectively, were allocated to noncontrolling interests, resulting in an increase of $2.8 million to our net income and $1.8 million reduction to our net loss, respectively. Our unaudited condensed consolidated statements of operations for the nine months ended September 30, 2019 include JiYa’s results for the period through March 11, 2019. ​ 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 $5.8 million and $6.0 million as of September 30, 2020 and December 31, 2019, 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. ​ One of the minority investment entities in which we have a 25% ownership interest is a germanium materials company in China. This company provides results to us only on a quarterly basis. We received its preliminary first quarter 2019 financial results in early April 2019 as well as its projections for significant losses going forward. Such projected losses would fully deplete our asset investment balance for this company in 2019. This company is experiencing significant disruptions due to upgrades and repairs required to comply with stronger environmental regulations in China. As a result, we determined that this asset was fully impaired and wrote the asset balance down to zero . This resulted in a $1.1 million impairment charge in our first quarter 2019 financial results. ​ AXT’s minority investment entities are not consolidated and are accounted for under the equity method. Excluding one fully impaired entity, the equity entities had the following summarized income information (in thousands) for the three and nine months ended September 30, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ ​ 2020 2019 2020 2019 Net revenue ​ $ 5,052 ​ $ 3,713 ​ $ 12,610 ​ $ 14,713 ​ Gross profit ​ $ 918 ​ $ 309 ​ $ 2,944 ​ $ 1,423 ​ Operating income (loss) ​ $ 136 ​ $ (436) ​ $ 598 ​ $ (1,857) ​ Net income (loss) ​ $ 7 ​ $ (502) ​ $ (151) ​ $ (2,518) ​ ​ 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 a gain of $45,000 and a loss of $0.2 million, respectively, for the three months ended September 30, 2020 and 2019. Our portion of the income and losses, including impairment charges, from these minority investment entities that are not consolidated and are accounted for under the equity method was a loss of $0.2 million and $1.7 million, respectively, for the nine months ended September 30, 2020 and 2019.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2020
Stockholders' Equity
Stockholders' Equity	Note 8. Stockholders’ Equity ​ Condensed Consolidated Statements of Changes in Stockholders’ Equity (in thousands) ​ The changes in stockholders’ equity by component for the three and nine months ended September 30, 2020 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, 2019 $ 3,532 $ 41 $ 236,957 $ (47,783) $ (4,862) ​ $ 187,885 $ 4,877 $ 192,762 ​ Common stock options exercised ​ ​ — ​ ​ — ​ ​ 441 ​ ​ — ​ ​ — ​ ​ 441 ​ ​ — ​ ​ 441 ​ Stock-based compensation ​ ​ — ​ ​ — ​ ​ 643 ​ ​ — ​ ​ — ​ ​ 643 ​ ​ — ​ ​ 643 ​ Net income (loss) ​ ​ — ​ ​ — ​ ​ — ​ ​ (178) ​ ​ — ​ ​ (178) ​ ​ 395 ​ ​ 217 ​ Other comprehensive loss ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (1,775) ​ ​ (1,775) ​ ​ (98) ​ ​ (1,873) ​ Balance as of March 31, 2020 ​ $ 3,532 ​ $ 41 ​ $ 238,041 ​ $ (47,961) ​ $ (6,637) ​ $ 187,016 ​ $ 5,174 ​ $ 192,190 ​ Common stock options exercised ​ ​ — ​ ​ — ​ ​ 72 ​ ​ — ​ ​ — ​ ​ 72 ​ ​ — ​ ​ 72 ​ Stock-based compensation ​ ​ — ​ ​ — ​ ​ 641 ​ ​ — ​ ​ — ​ ​ 641 ​ ​ — ​ ​ 641 ​ Net income ​ ​ — ​ ​ — ​ ​ — ​ ​ 361 ​ ​ — ​ ​ 361 ​ ​ 598 ​ ​ 959 ​ Net dividend declared by joint ventures ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (89) ​ ​ (89) ​ Other comprehensive income ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 272 ​ ​ 272 ​ ​ 9 ​ ​ 281 ​ Balance as of June 30, 2020 $ 3,532 ​ $ 41 ​ $ 238,754 ​ $ (47,600) ​ $ (6,365) ​ $ 188,362 ​ $ 5,692 ​ $ 194,054 ​ Common stock options exercised ​ ​ — ​ ​ — ​ ​ 624 ​ ​ — ​ ​ — ​ ​ 624 ​ ​ — ​ ​ 624 ​ Sale of subsidiary shares to noncontrolling interests ​ ​ — ​ ​ — ​ ​ 396 ​ ​ — ​ ​ — ​ ​ 396 ​ ​ — ​ ​ 396 ​ Stock-based compensation ​ ​ — ​ ​ — ​ ​ 648 ​ ​ — ​ ​ — ​ ​ 648 ​ ​ — ​ ​ 648 ​ Net income ​ ​ — ​ ​ — ​ ​ — ​ ​ 991 ​ ​ — ​ ​ 991 ​ ​ 490 ​ ​ 1,481 ​ Other comprehensive income ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 4,373 ​ ​ 4,373 ​ ​ 316 ​ ​ 4,689 ​ Balance as of September 30, 2020 $ 3,532 ​ $ 41 ​ $ 240,422 ​ $ (46,609) ​ $ (1,992) ​ $ 195,394 ​ $ 6,498 ​ $ 201,892 ​ ​ The changes in stockholders’ equity by component for the three and nine months ended September 30, 2019 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, 2018 $ 3,532 $ 40 $ 234,418 $ (45,183) $ (1,972) ​ $ 190,835 $ 3,697 $ 194,532 Reclassification out of accumulated other comprehensive income and noncontrolling interests upon the deconsolidation of a subsidiary ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (1,150) ​ ​ (1,150) ​ ​ 533 ​ ​ (617) Stock-based compensation ​ ​ — ​ ​ — ​ ​ 558 ​ ​ — ​ ​ — ​ ​ 558 ​ ​ — ​ ​ 558 Net income (loss) ​ ​ — ​ ​ — ​ ​ — ​ ​ (1,104) ​ ​ — ​ ​ (1,104) ​ ​ 81 ​ ​ (1,023) Other comprehensive income ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 2,389 ​ ​ 2,389 ​ ​ 142 ​ ​ 2,531 Balance as of March 31, 2019 ​ $ 3,532 ​ $ 40 ​ $ 234,976 ​ $ (46,287) ​ $ (733) ​ $ 191,528 ​ $ 4,453 ​ $ 195,981 Common stock options exercised ​ ​ — ​ ​ — ​ ​ 232 ​ ​ — ​ ​ — ​ ​ 232 ​ ​ — ​ ​ 232 Purchase of subsidiary shares from noncontrolling interests ​ ​ — ​ ​ — ​ ​ (74) ​ ​ — ​ ​ — ​ ​ (74) ​ ​ (339) ​ ​ (413) Stock-based compensation ​ ​ — ​ ​ — ​ ​ 568 ​ ​ — ​ ​ — ​ ​ 568 ​ ​ — ​ ​ 568 Net income ​ ​ — ​ ​ — ​ ​ — ​ ​ 1,451 ​ ​ — ​ ​ 1,451 ​ ​ 287 ​ ​ 1,738 Other comprehensive loss ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (2,397) ​ ​ (2,397) ​ ​ (54) ​ ​ (2,451) Balance as of June 30, 2019 $ 3,532 ​ $ 40 ​ $ 235,702 ​ $ (44,836) ​ $ (3,130) ​ $ 191,308 ​ $ 4,347 ​ $ 195,655 Common stock options exercised ​ ​ — ​ ​ — ​ ​ 35 ​ ​ — ​ ​ — ​ ​ 35 ​ ​ — ​ ​ 35 Stock-based compensation ​ ​ — ​ ​ — ​ ​ 583 ​ ​ — ​ ​ — ​ ​ 583 ​ ​ — ​ ​ 583 Net income ​ ​ — ​ ​ — ​ ​ — ​ ​ (898) ​ ​ — ​ ​ (898) ​ ​ 403 ​ ​ (495) Other comprehensive loss ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (4,110) ​ ​ (4,110) ​ ​ (214) ​ ​ (4,324) Balance as of September 30, 2019 $ 3,532 ​ $ 40 ​ $ 236,320 ​ $ (45,734) ​ $ (7,240) ​ $ 186,918 ​ $ 4,536 ​ $ 191,454 ​ ​ Except as shown above related to the deconsolidation of a subsidiary, 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 2019. During the three and nine months ended September 30, 2020, we did not repurchase any shares under the approved stock repurchase program. As of September 30, 2020, 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	9 Months Ended
	Sep. 30, 2020
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 recognized as expense over the employee’s requisite service period of the award. All of our stock compensation is accounted for as an equity instrument. ​ The following table summarizes compensation costs related to our stock-based awards (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ ​ 2020 2019 2020 2019 Cost of revenue ​ $ 28 ​ $ 31 ​ $ 83 ​ $ 92 ​ Selling, general and administrative ​ 496 ​ 433 ​ 1,480 ​ 1,296 ​ Research and development ​ 124 ​ 119 ​ 369 ​ 321 ​ Total stock-based compensation ​ 648 ​ 583 ​ 1,932 ​ 1,709 ​ Tax effect on stock-based compensation ​ — ​ — ​ — ​ — ​ Net effect on net income (loss) ​ $ 648 ​ $ 583 ​ $ 1,932 ​ $ 1,709 ​ ​ As of September 30, 2020, the unamortized compensation costs related to unvested stock options granted to employees under our stock option plan was approximately $1.0 million, net of estimated forfeitures of $80,000 . 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 September 30, 2020 and December 31, 2019 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 and nine months ended September 30, 2020 and 2019. ​ The following table summarizes the stock option transactions during the nine months ended September 30, 2020 (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, 2020 2,953 ​ $ 4.00 5.95 ​ $ 3,040 ​ Granted — ​ — ​ — ​ ​ — ​ Exercised (460) ​ 2.47 ​ — ​ ​ — ​ Canceled and expired (162) ​ 5.83 ​ — ​ ​ — ​ Balance as of September 30, 2020 2,331 ​ $ 4.18 5.89 ​ $ 5,061 ​ Options vested as of September 30, 2020 and unvested options expected to vest, net of forfeitures 2,313 ​ $ 4.18 5.87 ​ $ 5,012 ​ Options exercisable as of September 30, 2020 1,703 ​ $ 4.20 4.88 ​ $ 3,675 ​ ​ The aggregate intrinsic value in the table above represents the total pretax intrinsic value, based on our closing price of $6.12 on September 30, 2020, 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 nine months ended September 30, 2020 is presented below (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ Grant Date Stock Awards Shares Share Value Non-vested as of January 1, 2020 ​ 939 ​ $ 5.02 ​ Granted 55 ​ $ 5.21 ​ Vested (127) ​ $ 6.00 ​ Forfeited ​ (12) ​ $ 5.69 ​ Non-vested as of September 30, 2020 855 ​ $ 4.88 ​ ​ As of September 30, 2020, the unamortized compensation costs related to unvested restricted stock awards was approximately $3.0 million, which is to be amortized on a straight-line basis over a weighted-average period of approximately 1.1 years.

Net Income (Loss) Per Share

Net Income (Loss) Per Share	9 Months Ended
	Sep. 30, 2020
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 ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ ​ 2020 2019 2020 2019 Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) attributable to AXT, Inc. ​ $ 991 ​ $ (898) ​ $ 1,174 ​ $ (551) ​ Less: Preferred stock dividends ​ (44) ​ (44) ​ (132) ​ (132) ​ Net income (loss) available to common stockholders ​ $ 947 ​ $ (942) ​ $ 1,042 ​ $ (683) ​ Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator for basic net income (loss) per share - weighted-average common shares ​ 40,152 ​ 39,466 ​ 39,978 ​ 39,438 ​ Effect of dilutive securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Common stock options ​ 575 ​ — ​ 510 ​ — ​ Restricted stock awards ​ 252 ​ — ​ 200 ​ — ​ Denominator for dilutive net income (loss) per common shares ​ 40,979 ​ 39,466 ​ 40,688 ​ 39,438 ​ Net income (loss) attributable to AXT, Inc. per common share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ $ 0.02 ​ $ (0.02) ​ $ 0.03 ​ $ (0.02) ​ Diluted ​ $ 0.02 ​ $ (0.02) ​ $ 0.03 ​ $ (0.02) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options excluded from diluted net income (loss) per share as the impact is anti-dilutive ​ 1,036 ​ 2,523 ​ 1,298 ​ 2,523 ​ Restricted stock excluded from diluted net income (loss) per share as the impact is anti-dilutive ​ 218 ​ 698 ​ 347 ​ 698 ​ ​ The 883,000 shares of $0.001 par value Series A preferred stock issued and outstanding as of September 30, 2020 and December 31, 2019, 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	9 Months Ended
	Sep. 30, 2020
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 ​ Nine Months Ended ​ ​ ​ ​ September 30, ​ September 30, ​ ​ ​ 2020 2019 2020 2019 Product Type: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Substrates ​ $ 20,311 ​ $ 15,959 ​ $ 54,066 ​ $ 53,324 ​ ​ Raw Materials and Other ​ 5,158 ​ 3,882 ​ 14,260 ​ 11,522 ​ ​ Total ​ $ 25,469 ​ $ 19,841 ​ $ 68,326 ​ $ 64,846 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Geographical Information ​ The following table represents revenue amounts (in thousands) reported for products shipped to customers in the corresponding geographic region: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ ​ September 30, ​ September 30, ​ ​ ​ 2020 2019 2020 2019 Geographical region: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ China ​ $ 10,568 ​ $ 5,117 ​ $ 23,045 ​ $ 21,870 ​ ​ Taiwan ​ ​ 3,333 ​ ​ 4,399 ​ ​ 12,908 ​ ​ 12,062 ​ ​ Japan ​ 2,233 ​ 1,339 ​ 5,265 ​ 4,641 ​ ​ Asia Pacific (excluding China, Taiwan and Japan) ​ ​ 1,446 ​ ​ 2,234 ​ ​ 4,503 ​ ​ 6,156 ​ ​ Europe (primarily Germany) ​ ​ 4,689 ​ ​ 4,737 ​ ​ 15,017 ​ ​ 13,752 ​ ​ North America (primarily the United States) ​ 3,200 ​ 2,015 ​ ​ 7,588 ​ ​ 6,365 ​ ​ Total ​ $ 25,469 ​ $ 19,841 ​ $ 68,326 ​ $ 64,846 ​ ​ ​ 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 ​ ​ ​ September 30, ​ December 31, ​ ​ 2020 2019 Long-lived assets by geographic region, net of depreciation: ​ ​ ​ ​ ​ ​ ​ North America ​ $ 857 ​ $ 1,069 ​ China ​ 110,140 ​ 99,272 ​ ​ ​ $ 110,997 ​ $ 100,341 ​ ​ Significant Customers ​ No customer represented 10% of our revenue for the three months ended ​ Two customers, represented 11% and 10% , respectively, of our revenue for the nine months ended represented 14% and 10% ​ 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 10% and 10% of our accounts receivable balance as of September 30, 2020 ,

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
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” on the condensed consolidated balance sheets, during the three and nine months ended September 30, 2020 and 2019 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ September 30, ​ September 30, ​ 2020 2019 2020 2019 Beginning accrued product warranty ​ $ 352 ​ $ 353 ​ $ 387 ​ $ 236 ​ Accruals for warranties issued ​ 195 ​ 146 ​ 384 ​ 388 ​ Adjustments related to pre-existing warranties including expirations and changes in estimates ​ 171 ​ 27 ​ 99 ​ 175 ​ Cost of warranty repair ​ (189) ​ (183) ​ (341) ​ (456) ​ Ending accrued product warranty ​ $ 529 ​ $ 343 ​ $ 529 ​ $ 343 ​ ​ 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 processing 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 tax credits 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 the 3-D sensing VCSELs), 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 September 30, 2020, 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 Income (Expense), Net

Other Income (Expense), Net	9 Months Ended
	Sep. 30, 2020
Other Income (Expense), Net
Other Income (Expense), Net	Note 13. Other Income (Expense), Net ​ Other income (expense), net for the three and nine months ended September 30, 2020, includes a grant of $0 ​ In addition, we incurred a foreign currency transaction exchange loss of $135,000 and gain of $165,000 for the three months ended September 30, 2020 and 2019, respectively. We incurred a foreign currency transaction exchange loss of $126,000 and gain of $85,000 for the nine months ended September 30, 2020 and 2019, respectively.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
Income Taxes
Income Taxes	Note 14. Income Taxes ​ We account for income taxes in accordance with ASC Topic 740, Income Taxes ​ 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 and nine months ended September 30, 2020 includes no interest and penalties. As of September 30, 2020, 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 and nine months ended September 30, 2020 was mostly related to our wholly owned China subsidiaries and our partially owned subsidiaries in China. Besides the state tax liabilities, no income taxes or benefits have been provided for U.S. operations for the three and nine months ended September 30, 2020 due to the loss in the U.S. and the uncertainty of generating future profit in the U.S., which has resulted in our deferred tax assets being fully reserved. ​ On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) was passed into law. The CARES Act includes several significant business tax provisions including modification to the taxable income limitation for utilization of net operating losses (“NOLs”) incurred in 2018, 2019 and 2020 and the ability to carry back NOLs from those years for a period of up to five years, an increase to the limitation on deductibility of certain business interest expense, bonus depreciation for purchases of qualified improvement property and special deductions on certain corporate charitable contributions. The Company analyzed the provisions of the CARES Act and determined there was no effect on its provision for the current period and will continue to evaluate the impact, if any, the CARES Act may have on the Company’s condensed consolidated financial statements and disclosures. ​ 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	9 Months Ended
	Sep. 30, 2020
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 ​ We receive payments from customers based on a billing schedule as established in our contracts. 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 September 30, 2020. The following table reflects the contract liabilities balance as of September 30, 2020 and December 31, 2019 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ 2020 ​ 2019 ​ Contract liabilities ​ $ (494) ​ $ (396) ​ During the three and nine months ended September 30, 2020, the Company recognized $8,000 and $242,000, respectively, of revenue that was included in the contract balances as of December 31, 2019. ​ ​ ​ ​ ​ ​ ​ 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	9 Months Ended
	Sep. 30, 2020
Bank Loans and Line of Credit
Bank Loans and Line of Credit	Note 16. Bank Loans and Line of Credit ​ On November 6, 2018, the Company entered into a Credit Agreement (the “Credit Agreement”), by and between the Company and Wells Fargo Bank, National Association (“Wells Fargo Bank”), which established a $10 million secured revolving line of credit with a $1.0 million letter of credit sublimit facility. The revolving credit facility is collateralized by substantially all of the assets of the Company located within the United States, subject to certain exceptions. The commitments under the Credit Agreement expire on November 30, 2020 and any loans thereunder will bear interest at a rate based on the daily one-month London Inter-bank Offered Rate (“LIBOR”) for the applicable interest period plus a margin of 2.00%. On February 5, 2020, the Company entered into the First Amendment to Credit Agreement (the “First Amendment”), by and between the Company and Wells Fargo Bank, which reduced the $10 million secured revolving line of credit under the Credit Agreement to $7 million. The commitments under the Credit Agreement, as amended by the First Amendment, expire on November 30, 2020 and any loans thereunder will bear interest at a rate based on the daily one-month LIBOR for the applicable interest period plus a margin of 2.5% . As of September 30, 2020, ​ On August 9, 2019, Tongmei entered into a 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 July 31, 2020. The credit facility is collateralized by Tongmei Baoding’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. ​ ​ 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 is due on March 22, 2021, however the credit facility contains an option to renew for an additional six months. As of September 30, 2020, $2.9 million was included in “Bank loan” in our condensed consolidated balance sheets. ​ ​ ​ ​

Leases

Leases	9 Months Ended
	Sep. 30, 2020
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 expires 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 ​ On January 1, 2019, we adopted Accounting Standard Update 2016-02, Leases Leases ​ We adopted ASC 842 using a modified retrospective approach for all leases existing at January 1, 2019. The adoption of ASC 842 had a material impact on our consolidated balance sheet. The most significant impact was the recognition of the operating lease right-of-use assets and the liability for operating leases. Accordingly, upon adoption, leases that were classified as operating leases under ASC 840 were classified as operating leases under ASC 842, and we recorded an adjustment of $1.1 million to operating practical expedients ​ 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 September 30, 2020, the maturities of our operating lease liabilities (excluding short-term leases) are as follows (in thousands): ​ ​ ​ ​ Maturity of Lease Liabilities ​ 2020 $ 129 2021 ​ 555 2022 ​ 571 2023 ​ 562 2024 ​ 274 Thereafter ​ 1,252 Total minimum lease payments ​ 3,343 Less: Interest ​ (507) Present value of lease obligations ​ 2,836 Less: Current portion, included in accrued liabilities ​ (421) Long-term portion of lease obligations $ 2,415 ​ The weighted average remaining lease term and the weighted-average discount rate for our operating leases as of each date is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ 2020 ​ 2019 ​ Weighted-average remaining lease term (years) ​ 7.34 ​ 7.94 ​ 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): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended ​ ​ ​ September 30, ​ ​ ​ 2020 ​ 2019 ​ Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ 324 ​ $ 159 ​ Supplemental noncash information on lease liabilities arising from obtaining right-of-use assets: ​ ​ ​ ​ ​ ​ ​ Leased assets obtained in exchange for new operating lease liabilities ​ $ — ​ $ 2,072 ​ ​ The components of lease expense are as follows (in thousands) within our condensed consolidated statements of operations: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ September 30, ​ September 30, ​ ​ 2020 ​ 2019 ​ 2020 ​ 2019 Operating lease ​ $ 128 ​ $ 106 ​ $ 383 ​ $ 229 Short-term lease expense ​ ​ 27 ​ ​ 14 ​ ​ 61 ​ ​ 42 Total ​ $ 155 ​ $ 120 ​ $ 444 ​ $ 271 ​

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2020
Recent Accounting Pronouncements
Recent Accounting Pronouncements	Note 18. Recent Accounting Pronouncements Accounting Standard Update (“ASU”) No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”) was issued in June 2016. Under ASU 2016-13, existing guidance on reporting credit losses for trade and other receivables and available for sale debt securities have been replaced with a new forward-looking “expected loss” model that has resulted in the earlier recognition of allowances for losses. Our adoption of ASU 2016-13 and its subsequent series of amendments during the three and nine months ended September 30, 2020 using the modified retrospective transition approach did not result in a material impact on our condensed consolidated financial statements. As part of our assessment of the adequacy of our allowances for credit losses, we consider a number of factors including, but not limited to, customer credit ratings, bankruptcy filings, published or estimated credit default rates, age of receivables, adequacy of our allowance for doubtful accounts and expected loss rates. ​

Investments and Fair Value Me_2

Investments and Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
Investments and Fair Value Measurements
Cash, cash equivalents and investments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2020 ​ December 31, 2019 ​ ​ ​ Gross Gross ​ ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Cost Gain (Loss) Value Cost Gain (Loss) Value Classified as: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash ​ $ 22,384 ​ $ — ​ $ — ​ $ 22,384 ​ $ 26,892 ​ $ — ​ $ — ​ $ 26,892 ​ Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit 1 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Total cash and cash equivalents ​ 22,384 ​ — ​ — ​ 22,384 ​ 26,892 ​ — ​ — ​ 26,892 ​ Investments (available-for-sale): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit 2 ​ 2,880 ​ 4 ​ ​ — ​ 2,884 ​ 2,400 ​ 2 ​ ​ — ​ 2,402 ​ Corporate bonds ​ 4,501 ​ 4 ​ — ​ 4,505 ​ 7,030 ​ 4 ​ (9) ​ 7,025 ​ Total investments ​ 7,381 ​ 8 ​ — ​ 7,389 ​ 9,430 ​ 6 ​ (9) ​ 9,427 ​ Total cash, cash equivalents and investments ​ $ 29,765 ​ $ 8 ​ $ — ​ $ 29,773 ​ $ 36,322 ​ $ 6 ​ $ (9) ​ $ 36,319 ​ Contractual maturities on investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Due within 1 year 3 ​ $ 4,501 ​ ​ ​ ​ ​ ​ ​ $ 4,505 ​ $ 9,430 ​ ​ ​ ​ ​ ​ ​ $ 9,427 ​ Due after 1 through 5 years 4 ​ 2,880 ​ ​ ​ ​ ​ ​ ​ 2,884 ​ — ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ $ 7,381 ​ ​ ​ ​ ​ ​ ​ $ 7,389 ​ $ 9,430 ​ ​ ​ ​ ​ ​ ​ $ 9,427 ​ 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 December 31, 2019 (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, 2019 ​ Value ​ (Loss) ​ Value ​ (Loss) ​ Value ​ (Loss) Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds ​ 4,515 ​ (9) ​ — ​ — ​ 4,515 ​ ​ (9) ​ Total in loss position ​ $ 4,515 ​ $ (9) ​ $ — ​ $ — ​ $ 4,515 ​ $ (9) ​
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 September 30, 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices in ​ ​ ​ Significant ​ ​ ​ ​ ​ Active Markets of ​ Significant Other ​ Unobservable ​ ​ Balance as of ​ Identical Assets ​ Observable Inputs ​ Inputs ​ September 30, 2020 (Level 1) (Level 2) (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents and investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ $ 2,884 ​ $ — ​ $ 2,884 ​ $ — ​ Corporate bonds ​ 4,505 ​ — ​ 4,505 ​ — ​ Total ​ $ 7,389 ​ $ — ​ $ 7,389 ​ $ — ​ ​ 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, 2019 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices in ​ ​ ​ Significant ​ ​ ​ ​ ​ Active Markets of ​ Significant Other ​ Unobservable ​ ​ Balance as of ​ Identical Assets ​ Observable Inputs ​ Inputs ​ December 31, 2019 (Level 1) (Level 2) (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents and investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Certificates of deposit ​ $ 2,402 ​ $ — ​ $ 2,402 ​ $ — ​ Corporate bonds ​ 7,025 ​ — ​ 7,025 ​ — ​ Total ​ $ 9,427 ​ $ — ​ $ 9,427 ​ $ — ​

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2020
Inventories
Components of inventories	The components of inventories are summarized below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2020 2019 Inventories: ​ ​ ​ ​ ​ ​ ​ Raw materials ​ $ 23,078 ​ $ 20,677 ​ Work in process ​ 23,166 ​ 24,946 ​ Finished goods ​ 2,113 ​ 3,529 ​ ​ ​ $ 48,357 ​ $ 49,152 ​

Property, Plant and Equipment_2

Property, Plant and Equipment, Net (Tables)	9 Months Ended
	Sep. 30, 2020
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): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ 2020 ​ 2019 ​ Property, plant and equipment: ​ ​ ​ ​ ​ ​ ​ Machinery and equipment, at cost ​ $ 46,207 ​ $ 45,742 ​ Less: accumulated depreciation and amortization ​ ​ (37,876) ​ ​ (37,115) ​ Building, at cost ​ ​ 39,870 ​ ​ 38,837 ​ Less: accumulated depreciation and amortization ​ ​ (14,070) ​ ​ (12,736) ​ Leasehold improvements, at cost ​ 5,903 ​ 4,877 ​ Less: accumulated depreciation and amortization ​ ​ (4,404) ​ ​ (4,035) ​ Construction in progress ​ 72,665 ​ 61,833 ​ ​ ​ $ 108,295 ​ $ 97,403 ​

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	9 Months Ended
	Sep. 30, 2020
Accrued Liabilities
Schedule of components of accrued liabilities	The components of accrued liabilities are summarized below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2020 2019 Preferred stock dividends payable ​ $ 2,901 ​ $ 2,901 ​ Accrued compensation and related charges ​ ​ 2,213 ​ ​ 3,307 ​ Payable in connection with land restoration of Nanjing JinMei factory ​ ​ 720 ​ ​ 703 ​ Accrued income taxes ​ ​ 714 ​ ​ 171 ​ Accrued professional services ​ ​ 659 ​ ​ 630 ​ Accrued product warranty ​ ​ 529 ​ ​ 387 ​ Advance from customers ​ ​ 494 ​ ​ 396 ​ Current portion of operating lease liabilities ​ ​ 421 ​ ​ 319 ​ Other tax payable ​ ​ 357 ​ ​ 50 ​ Current portion of royalty payments ​ ​ 300 ​ ​ — ​ Payable in connection with construction ​ ​ 208 ​ ​ 1,447 ​ Other personnel-related costs ​ ​ 142 ​ ​ 180 ​ Accrual for sales returns ​ ​ 92 ​ ​ 26 ​ Payable in connection with repurchase of subsidiaries shares ​ ​ 49 ​ ​ 151 ​ Other accrued liabilities ​ ​ 1,043 ​ ​ 1,013 ​ ​ ​ $ 10,842 ​ $ 11,681 ​

Investments in Privately-Held_2

Investments in Privately-Held Raw Material Companies (Tables)	9 Months Ended
	Sep. 30, 2020
Investments in Privately-Held Raw Material Companies
Summary of investments	As of September 30, 2020, the investments are summarized below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Investment Balance as of ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ Accounting ​ Ownership ​ Company 2020 2019 Method Percentage ​ Nanjing JinMei Gallium Co., Ltd. ​ $ 592 ​ $ 592 Consolidated **100 % Chaoyang JinMei Gallium Co., Ltd. ​ $ 1,820 ​ $ 1,820 ​ Consolidated ​ ***91.5 % Beijing JiYa Semiconductor Material Co., Ltd. ​ ​ N/A ​ ​ N/A ​ Consolidated ​ *46 % Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd. ​ 1,346 ​ 1,346 Consolidated 63 % ​ ​ $ 3,758 ​ $ 3,758 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Donghai County Dongfang High Purity Electronic Materials Co., Ltd. ​ $ 1,509 ​ $ 1,326 Equity 46 % Beijing JiYa Semiconductor Material Co., Ltd. ​ ​ 1,192 ​ ​ 1,621 ​ Equity ​ *39 % Xilingol Tongli Germanium Co., Ltd. ​ — ​ — Equity 25 % Xiaoyi XingAn Gallium Co., Ltd. ​ ​ 2,605 ​ ​ 2,367 ​ Equity ​ 25 % Emeishan Jia Mei High Purity Metals Co., Ltd. ​ 520 ​ 647 Equity 25 % ​ ​ $ 5,826 ​ $ 5,961 ​ ​ ​ ​ ​
Summary of gain on deconsolidation	​ ​ ​ ​ ​ ​ ​ Amount ​ (in thousands) Fair value of the consideration received ​ $ 366 Fair value of the retained investment in Beijing JiYa Semiconductor Material Co., Ltd. ​ ​ 2,040 Carrying value of noncontrolling interests, net of accumulated other comprehensive income attributable to subsidiary ​ ​ 617 Derecognition of Beijing JiYa Semiconductor Material Co., Ltd.'s net asset ​ ​ (2,848) Gain recognized on deconsolidation of Beijing JiYa Semiconductor Material Co., Ltd. ​ $ 175 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount ​ ​ (in thousands) Fair value of the retained investment in Beijing JiYa Semiconductor Material Co., Ltd. ​ $ 2,040 Carrying value of retained noncontrolling investment ​ ​ (1,559) Gain on retained noncontrolling investment due to remeasurement ​ $ 481
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 entities had the following summarized income information (in thousands) for the three and nine months ended September 30, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ ​ 2020 2019 2020 2019 Net revenue ​ $ 5,052 ​ $ 3,713 ​ $ 12,610 ​ $ 14,713 ​ Gross profit ​ $ 918 ​ $ 309 ​ $ 2,944 ​ $ 1,423 ​ Operating income (loss) ​ $ 136 ​ $ (436) ​ $ 598 ​ $ (1,857) ​ Net income (loss) ​ $ 7 ​ $ (502) ​ $ (151) ​ $ (2,518) ​

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2020
Stockholders' Equity
Consolidated statements of changes in stockholders' equity	Condensed Consolidated Statements of Changes in Stockholders’ Equity (in thousands) ​ The changes in stockholders’ equity by component for the three and nine months ended September 30, 2020 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, 2019 $ 3,532 $ 41 $ 236,957 $ (47,783) $ (4,862) ​ $ 187,885 $ 4,877 $ 192,762 ​ Common stock options exercised ​ ​ — ​ ​ — ​ ​ 441 ​ ​ — ​ ​ — ​ ​ 441 ​ ​ — ​ ​ 441 ​ Stock-based compensation ​ ​ — ​ ​ — ​ ​ 643 ​ ​ — ​ ​ — ​ ​ 643 ​ ​ — ​ ​ 643 ​ Net income (loss) ​ ​ — ​ ​ — ​ ​ — ​ ​ (178) ​ ​ — ​ ​ (178) ​ ​ 395 ​ ​ 217 ​ Other comprehensive loss ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (1,775) ​ ​ (1,775) ​ ​ (98) ​ ​ (1,873) ​ Balance as of March 31, 2020 ​ $ 3,532 ​ $ 41 ​ $ 238,041 ​ $ (47,961) ​ $ (6,637) ​ $ 187,016 ​ $ 5,174 ​ $ 192,190 ​ Common stock options exercised ​ ​ — ​ ​ — ​ ​ 72 ​ ​ — ​ ​ — ​ ​ 72 ​ ​ — ​ ​ 72 ​ Stock-based compensation ​ ​ — ​ ​ — ​ ​ 641 ​ ​ — ​ ​ — ​ ​ 641 ​ ​ — ​ ​ 641 ​ Net income ​ ​ — ​ ​ — ​ ​ — ​ ​ 361 ​ ​ — ​ ​ 361 ​ ​ 598 ​ ​ 959 ​ Net dividend declared by joint ventures ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (89) ​ ​ (89) ​ Other comprehensive income ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 272 ​ ​ 272 ​ ​ 9 ​ ​ 281 ​ Balance as of June 30, 2020 $ 3,532 ​ $ 41 ​ $ 238,754 ​ $ (47,600) ​ $ (6,365) ​ $ 188,362 ​ $ 5,692 ​ $ 194,054 ​ Common stock options exercised ​ ​ — ​ ​ — ​ ​ 624 ​ ​ — ​ ​ — ​ ​ 624 ​ ​ — ​ ​ 624 ​ Sale of subsidiary shares to noncontrolling interests ​ ​ — ​ ​ — ​ ​ 396 ​ ​ — ​ ​ — ​ ​ 396 ​ ​ — ​ ​ 396 ​ Stock-based compensation ​ ​ — ​ ​ — ​ ​ 648 ​ ​ — ​ ​ — ​ ​ 648 ​ ​ — ​ ​ 648 ​ Net income ​ ​ — ​ ​ — ​ ​ — ​ ​ 991 ​ ​ — ​ ​ 991 ​ ​ 490 ​ ​ 1,481 ​ Other comprehensive income ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 4,373 ​ ​ 4,373 ​ ​ 316 ​ ​ 4,689 ​ Balance as of September 30, 2020 $ 3,532 ​ $ 41 ​ $ 240,422 ​ $ (46,609) ​ $ (1,992) ​ $ 195,394 ​ $ 6,498 ​ $ 201,892 ​ ​ The changes in stockholders’ equity by component for the three and nine months ended September 30, 2019 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, 2018 $ 3,532 $ 40 $ 234,418 $ (45,183) $ (1,972) ​ $ 190,835 $ 3,697 $ 194,532 Reclassification out of accumulated other comprehensive income and noncontrolling interests upon the deconsolidation of a subsidiary ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (1,150) ​ ​ (1,150) ​ ​ 533 ​ ​ (617) Stock-based compensation ​ ​ — ​ ​ — ​ ​ 558 ​ ​ — ​ ​ — ​ ​ 558 ​ ​ — ​ ​ 558 Net income (loss) ​ ​ — ​ ​ — ​ ​ — ​ ​ (1,104) ​ ​ — ​ ​ (1,104) ​ ​ 81 ​ ​ (1,023) Other comprehensive income ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 2,389 ​ ​ 2,389 ​ ​ 142 ​ ​ 2,531 Balance as of March 31, 2019 ​ $ 3,532 ​ $ 40 ​ $ 234,976 ​ $ (46,287) ​ $ (733) ​ $ 191,528 ​ $ 4,453 ​ $ 195,981 Common stock options exercised ​ ​ — ​ ​ — ​ ​ 232 ​ ​ — ​ ​ — ​ ​ 232 ​ ​ — ​ ​ 232 Purchase of subsidiary shares from noncontrolling interests ​ ​ — ​ ​ — ​ ​ (74) ​ ​ — ​ ​ — ​ ​ (74) ​ ​ (339) ​ ​ (413) Stock-based compensation ​ ​ — ​ ​ — ​ ​ 568 ​ ​ — ​ ​ — ​ ​ 568 ​ ​ — ​ ​ 568 Net income ​ ​ — ​ ​ — ​ ​ — ​ ​ 1,451 ​ ​ — ​ ​ 1,451 ​ ​ 287 ​ ​ 1,738 Other comprehensive loss ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (2,397) ​ ​ (2,397) ​ ​ (54) ​ ​ (2,451) Balance as of June 30, 2019 $ 3,532 ​ $ 40 ​ $ 235,702 ​ $ (44,836) ​ $ (3,130) ​ $ 191,308 ​ $ 4,347 ​ $ 195,655 Common stock options exercised ​ ​ — ​ ​ — ​ ​ 35 ​ ​ — ​ ​ — ​ ​ 35 ​ ​ — ​ ​ 35 Stock-based compensation ​ ​ — ​ ​ — ​ ​ 583 ​ ​ — ​ ​ — ​ ​ 583 ​ ​ — ​ ​ 583 Net income ​ ​ — ​ ​ — ​ ​ — ​ ​ (898) ​ ​ — ​ ​ (898) ​ ​ 403 ​ ​ (495) Other comprehensive loss ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (4,110) ​ ​ (4,110) ​ ​ (214) ​ ​ (4,324) Balance as of September 30, 2019 $ 3,532 ​ $ 40 ​ $ 236,320 ​ $ (45,734) ​ $ (7,240) ​ $ 186,918 ​ $ 4,536 ​ $ 191,454

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2020
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 ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ ​ 2020 2019 2020 2019 Cost of revenue ​ $ 28 ​ $ 31 ​ $ 83 ​ $ 92 ​ Selling, general and administrative ​ 496 ​ 433 ​ 1,480 ​ 1,296 ​ Research and development ​ 124 ​ 119 ​ 369 ​ 321 ​ Total stock-based compensation ​ 648 ​ 583 ​ 1,932 ​ 1,709 ​ Tax effect on stock-based compensation ​ — ​ — ​ — ​ — ​ Net effect on net income (loss) ​ $ 648 ​ $ 583 ​ $ 1,932 ​ $ 1,709 ​
Summary of stock option activity	The following table summarizes the stock option transactions during the nine months ended September 30, 2020 (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, 2020 2,953 ​ $ 4.00 5.95 ​ $ 3,040 ​ Granted — ​ — ​ — ​ ​ — ​ Exercised (460) ​ 2.47 ​ — ​ ​ — ​ Canceled and expired (162) ​ 5.83 ​ — ​ ​ — ​ Balance as of September 30, 2020 2,331 ​ $ 4.18 5.89 ​ $ 5,061 ​ Options vested as of September 30, 2020 and unvested options expected to vest, net of forfeitures 2,313 ​ $ 4.18 5.87 ​ $ 5,012 ​ Options exercisable as of September 30, 2020 1,703 ​ $ 4.20 4.88 ​ $ 3,675 ​
Summary of restricted stock awards activity	A summary of activity related to restricted stock awards for the nine months ended September 30, 2020 is presented below (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ Grant Date Stock Awards Shares Share Value Non-vested as of January 1, 2020 ​ 939 ​ $ 5.02 ​ Granted 55 ​ $ 5.21 ​ Vested (127) ​ $ 6.00 ​ Forfeited ​ (12) ​ $ 5.69 ​ Non-vested as of September 30, 2020 855 ​ $ 4.88 ​

Net Income (Loss) Per Share (Ta

Net Income (Loss) Per Share (Tables)	9 Months Ended
	Sep. 30, 2020
Net Income (Loss) Per Share
Reconciliation of numerators and denominators of basic and diluted net income 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 ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ ​ 2020 2019 2020 2019 Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) attributable to AXT, Inc. ​ $ 991 ​ $ (898) ​ $ 1,174 ​ $ (551) ​ Less: Preferred stock dividends ​ (44) ​ (44) ​ (132) ​ (132) ​ Net income (loss) available to common stockholders ​ $ 947 ​ $ (942) ​ $ 1,042 ​ $ (683) ​ Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator for basic net income (loss) per share - weighted-average common shares ​ 40,152 ​ 39,466 ​ 39,978 ​ 39,438 ​ Effect of dilutive securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Common stock options ​ 575 ​ — ​ 510 ​ — ​ Restricted stock awards ​ 252 ​ — ​ 200 ​ — ​ Denominator for dilutive net income (loss) per common shares ​ 40,979 ​ 39,466 ​ 40,688 ​ 39,438 ​ Net income (loss) attributable to AXT, Inc. per common share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ $ 0.02 ​ $ (0.02) ​ $ 0.03 ​ $ (0.02) ​ Diluted ​ $ 0.02 ​ $ (0.02) ​ $ 0.03 ​ $ (0.02) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options excluded from diluted net income (loss) per share as the impact is anti-dilutive ​ 1,036 ​ 2,523 ​ 1,298 ​ 2,523 ​ Restricted stock excluded from diluted net income (loss) per share as the impact is anti-dilutive ​ 218 ​ 698 ​ 347 ​ 698 ​

Segment Information and Forei_2

Segment Information and Foreign Operations (Tables)	9 Months Ended
	Sep. 30, 2020
Segment Information and Foreign Operations
Revenues reported by product type	The following table represents revenue amounts (in thousands) by product type: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ ​ September 30, ​ September 30, ​ ​ ​ 2020 2019 2020 2019 Product Type: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Substrates ​ $ 20,311 ​ $ 15,959 ​ $ 54,066 ​ $ 53,324 ​ ​ Raw Materials and Other ​ 5,158 ​ 3,882 ​ 14,260 ​ 11,522 ​ ​ Total ​ $ 25,469 ​ $ 19,841 ​ $ 68,326 ​ $ 64,846 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
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 ​ Nine Months Ended ​ ​ ​ ​ September 30, ​ September 30, ​ ​ ​ 2020 2019 2020 2019 Geographical region: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ China ​ $ 10,568 ​ $ 5,117 ​ $ 23,045 ​ $ 21,870 ​ ​ Taiwan ​ ​ 3,333 ​ ​ 4,399 ​ ​ 12,908 ​ ​ 12,062 ​ ​ Japan ​ 2,233 ​ 1,339 ​ 5,265 ​ 4,641 ​ ​ Asia Pacific (excluding China, Taiwan and Japan) ​ ​ 1,446 ​ ​ 2,234 ​ ​ 4,503 ​ ​ 6,156 ​ ​ Europe (primarily Germany) ​ ​ 4,689 ​ ​ 4,737 ​ ​ 15,017 ​ ​ 13,752 ​ ​ North America (primarily the United States) ​ 3,200 ​ 2,015 ​ ​ 7,588 ​ ​ 6,365 ​ ​ Total ​ $ 25,469 ​ $ 19,841 ​ $ 68,326 ​ $ 64,846 ​ ​
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 ​ ​ ​ September 30, ​ December 31, ​ ​ 2020 2019 Long-lived assets by geographic region, net of depreciation: ​ ​ ​ ​ ​ ​ ​ North America ​ $ 857 ​ $ 1,069 ​ China ​ 110,140 ​ 99,272 ​ ​ ​ $ 110,997 ​ $ 100,341 ​

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies
Product warranty accrued liability	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ September 30, ​ September 30, ​ 2020 2019 2020 2019 Beginning accrued product warranty ​ $ 352 ​ $ 353 ​ $ 387 ​ $ 236 ​ Accruals for warranties issued ​ 195 ​ 146 ​ 384 ​ 388 ​ Adjustments related to pre-existing warranties including expirations and changes in estimates ​ 171 ​ 27 ​ 99 ​ 175 ​ Cost of warranty repair ​ (189) ​ (183) ​ (341) ​ (456) ​ Ending accrued product warranty ​ $ 529 ​ $ 343 ​ $ 529 ​ $ 343 ​

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2020
Revenue
Schedule of amounts recorded in accrued liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ 2020 ​ 2019 ​ Contract liabilities ​ $ (494) ​ $ (396) ​ During the three and nine months ended September 30, 2020, the Company recognized $8,000 and $242,000, respectively, of revenue that was included in the contract balances as of December 31, 2019. ​ ​ ​ ​ ​ ​

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2020
Leases
Summary of maturities of our operating lease liabilities	As of September 30, 2020, the maturities of our operating lease liabilities (excluding short-term leases) are as follows (in thousands): ​ ​ ​ ​ Maturity of Lease Liabilities ​ 2020 $ 129 2021 ​ 555 2022 ​ 571 2023 ​ 562 2024 ​ 274 Thereafter ​ 1,252 Total minimum lease payments ​ 3,343 Less: Interest ​ (507) Present value of lease obligations ​ 2,836 Less: Current portion, included in accrued liabilities ​ (421) Long-term portion of lease obligations $ 2,415
Schedule of weighted-average remaining lease term and the weighted-average discount rate of operating leases	​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ 2020 ​ 2019 ​ Weighted-average remaining lease term (years) ​ 7.34 ​ 7.94 ​ 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): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended ​ ​ ​ September 30, ​ ​ ​ 2020 ​ 2019 ​ Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ 324 ​ $ 159 ​ Supplemental noncash information on lease liabilities arising from obtaining right-of-use assets: ​ ​ ​ ​ ​ ​ ​ Leased assets obtained in exchange for new operating lease liabilities ​ $ — ​ $ 2,072 ​
Summary of components of lease expense	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ September 30, ​ September 30, ​ ​ 2020 ​ 2019 ​ 2020 ​ 2019 Operating lease ​ $ 128 ​ $ 106 ​ $ 383 ​ $ 229 Short-term lease expense ​ ​ 27 ​ ​ 14 ​ ​ 61 ​ ​ 42 Total ​ $ 155 ​ $ 120 ​ $ 444 ​ $ 271

Basis of Presentation (Details)

Basis of Presentation (Details)

Jun. 15, 2018USD ($)

Aug. 31, 2020USD ($)

May 31, 2019USD ($)

Sep. 30, 2018USD ($)

Mar. 31, 2019USD ($)

Sep. 30, 2020USD ($)company

Dec. 31, 2019company

Jul. 31, 2020

Apr. 30, 2019

Mar. 11, 2019

Mar. 10, 2019

Aug. 31, 2018

Jun. 14, 2018

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

Number of equity method investments | company

5

5

Additional percentage of ownership, consolidated method

2

Proceeds from Divestiture of Interest in Consolidated Subsidiaries

$ 366,000

$ 366,000

Nanjing JinMei Gallium Co., Ltd Investment

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

Additional percentage of ownership, consolidated method

12

3

Purchase of subsidiary shares from noncontrolling interest

$ 1,400,000

$ 413,000

$ 252,000

Chaoyang JinMei Gallium Co., Ltd[member]

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

Additional percentage of ownership, consolidated method

8.5

Purchase of subsidiary shares from noncontrolling interest

$ 396,000

Percentage Of Ownership Interest Sold

8.50%

Proceeds from Divestiture of Interest in Consolidated Subsidiaries

$ 396,000

Beijing JiYa Semiconductor Material Co., Ltd

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

Percentage of ownership, consolidated method (in hundredths)

39.00%

46.00%

Nanjing JinMei Gallium Co., Ltd Investment

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

Percentage of ownership, consolidated method (in hundredths)

100.00%

97.00%

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

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

Percentage of ownership, consolidated method (in hundredths)

100.00%

95.00%

83.00%

Chaoyang JinMei Gallium Co., Ltd[member]

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

Percentage of ownership, consolidated method (in hundredths)

91.50%

100.00%

Chaoyang JinMei Gallium Co., Ltd[member] | Chaoyang JinMei Gallium Co., Ltd[member]

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

Percentage of ownership, consolidated method (in hundredths)

91.50%

91.50%

100.00%

Percentage Of Ownership Interest Sold

8.50%

Proceeds from Divestiture of Interest in Consolidated Subsidiaries

$ 396,000

Investments and Fair Value Me_3

Investments and Fair Value Measurements (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Cash, cash equivalents and investments [Abstract]
Cash	$ 22,384	$ 26,892
Cash equivalents [Abstract]
Total cash and cash equivalents	22,384	26,892
Amortized Cost	7,381	9,430
Cash, cash equivalents and investments, amortized costs	29,765	36,322
Gross Unrealized Gain	8	6
Gross Unrealized (Loss)		(9)
Fair Value	7,389	9,427
Cash, cash equivalents and investments, amortized costs	29,773	36,319
Contractual maturities on investments, amortized cost basis [Abstract]
Due within 1 year	4,501	9,430
Due after 1 through 5 years	2,880
Investments, amortized cost	7,381	9,430
Contractual maturities on investments, fair value basis [Abstract]
Due within 1 year	4,505	9,427
Due after 1 through 5 years	2,884
Investments, fair value	7,389	9,427
Total Investments
Cash equivalents [Abstract]
Amortized Cost	7,381	9,430
Gross Unrealized Gain	8	6
Gross Unrealized (Loss)		(9)
Fair Value	7,389	9,427
Contractual maturities on investments, amortized cost basis [Abstract]
Investments, amortized cost	7,381	9,430
Contractual maturities on investments, fair value basis [Abstract]
Investments, fair value	7,389	9,427
Certificates of Deposit [Member]
Cash equivalents [Abstract]
Amortized Cost	2,880	2,400
Gross Unrealized Gain	4	2
Fair Value	2,884	2,402
Contractual maturities on investments, amortized cost basis [Abstract]
Investments, amortized cost	2,880	2,400
Contractual maturities on investments, fair value basis [Abstract]
Investments, fair value	2,884	2,402
Corporate Bonds [Member]
Cash equivalents [Abstract]
Amortized Cost	4,501	7,030
Gross Unrealized Gain	4	4
Gross Unrealized (Loss)		(9)
Fair Value	4,505	7,025
Contractual maturities on investments, amortized cost basis [Abstract]
Investments, amortized cost	4,501	7,030
Contractual maturities on investments, fair value basis [Abstract]
Investments, fair value	$ 4,505	$ 7,025

Investments and Fair Value Me_4

Investments and Fair Value Measurements - Investment Category and Length (Details) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Sep. 30, 2020USD ($)company	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)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						$ 4,515
Gross unrealized loss, in loss position less than twelve months						(9)
Fair value, total in loss position						4,515
Gross unrealized loss, total in loss position						(9)
Minority Investments
Investments, equity method	$ 5,826			$ 5,826		$ 5,961
Number of equity method investments | company				5		5
Impairment charge	0	$ 0	$ 1,100	$ 0	$ 1,100
Xilingol Tongli Germanium Co. Ltd Investment | Xilingol Tongli Germanium Co. Ltd Investment
Minority Investments
Investments, equity method	$ 0			$ 0
Ownership (as a percent)	25.00%			25.00%
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						$ 4,515
Gross unrealized loss, in loss position less than twelve months						(9)
Fair value, total in loss position						4,515
Gross unrealized loss, total in loss position						(9)
Other assets
Minority Investments
Investments, equity method	$ 5,800			$ 5,800		$ 6,000

Investments and Fair Value Me_5

Investments and Fair Value Measurements - Recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019
Assets, Fair Value Disclosure [Abstract]
Investments, amortized cost	$ 7,389	$ 7,389	$ 9,427
Fair Value, Transfers Between Level 1 and Level 2, Description and Policy [Abstract]
Transfer from Level 1 to Level 2 , assets	0	0
Transfer from Level 2 to Level 1 , assets	0	0
Transfers into Level 3, assets	0	0
Transfer out of Level 3, assets		0
Recurring
Assets, Fair Value Disclosure [Abstract]
Total	7,389	7,389	9,427
Recurring | Certificates of Deposit [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents, fair value disclosure	2,884	2,884	2,402
Recurring | Corporate Bonds [Member]
Assets, Fair Value Disclosure [Abstract]
Investments, amortized cost	4,505	4,505	7,025
Recurring | Significant Other Observable Inputs (Level 2)
Assets, Fair Value Disclosure [Abstract]
Total	7,389	7,389	9,427
Recurring | Significant Other Observable Inputs (Level 2) | Certificates of Deposit [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents, fair value disclosure	2,884	2,884	2,402
Recurring | Significant Other Observable Inputs (Level 2) | Corporate Bonds [Member]
Assets, Fair Value Disclosure [Abstract]
Investments, amortized cost	$ 4,505	$ 4,505	$ 7,025

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Inventories
Raw materials	$ 23,078	$ 20,677
Work in process	23,166	24,946
Finished goods	2,113	3,529
Inventories, Total	48,357	49,152
Inventory reserve	16,900	16,400
Excess and obsolete inventory	$ 86,000	$ 91,000

Property, Plant and Equipment_3

Property, Plant and Equipment, Net (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019
Property, plant and equipment [Abstract]
Property, plant and equipment, net	$ 108,295	$ 108,295	$ 97,403
Service Life
Property, plant and equipment [Abstract]
Decrease in manufacturing costs as a result of lower depreciation	$ 300	$ 900
Decrease in net loss per share, basic and diluted, as a result of lower depreciation	$ 0.01	$ 0.03
Machinery and equipment
Property, plant and equipment [Abstract]
Property, plant and equipment, gross	$ 46,207	$ 46,207	45,742
Less: accumulated depreciation and amortization	(37,876)	(37,876)	(37,115)
Building
Property, plant and equipment [Abstract]
Property, plant and equipment, gross	39,870	39,870	38,837
Less: accumulated depreciation and amortization	(14,070)	(14,070)	(12,736)
Leasehold improvements
Property, plant and equipment [Abstract]
Property, plant and equipment, gross	5,903	5,903	4,877
Less: accumulated depreciation and amortization	(4,404)	(4,404)	(4,035)
Construction in progress
Property, plant and equipment [Abstract]
Property, plant and equipment, gross	72,665	72,665	61,833
Construction in progress Dingxin and Kazuo locations
Property, plant and equipment [Abstract]
Property, plant and equipment, gross	57,800	57,800	48,800
Construction in progress manufacturing equipment purchases
Property, plant and equipment [Abstract]
Property, plant and equipment, gross	4,200	4,200	3,400
Construction in progress other consolidated subsidiaries
Property, plant and equipment [Abstract]
Property, plant and equipment, gross	$ 10,700	$ 10,700	$ 9,600

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Components of accrued liabilities
Preferred stock dividends payable	$ 2,901	$ 2,901
Accrued compensation and related charges	2,213	3,307
Payable in connection with land restoration of Nanjing JinMei factory	720	703
Accrued income taxes	714	171
Accrued professional services	659	630
Accrued product warranty	529	387
Advance from customers	494	396
Current portion of operating lease liabilities	421	319
Other tax payable	357	50
Current portion of royalty payments	300
Payable in connection with construction	208	1,447
Other personnel-related costs	142	180
Accrual for sales returns	92	26
Payable in connection with repurchase of subsidiaries shares	49	151
Other accrued liabilities	1,043	1,013
Accrued liabilities, Total	$ 10,842	$ 11,681

Related Party Transactions (Det

Related Party Transactions (Details)	Nov. 02, 2017USD ($)	Mar. 31, 2020USD ($)	May 31, 2019USD ($)	Nov. 30, 2017USD ($)	Jul. 31, 2017USD ($)installment	Apr. 30, 2016USD ($)	Sep. 30, 2020USD ($)ft²	Sep. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Jun. 30, 2017USD ($)	Sep. 30, 2020USD ($)ft²	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Mar. 11, 2019	Mar. 10, 2019
Related Party Transaction [Line Items]
Proceeds from sale of previously consolidated subsidiary shares									$ 366,000		$ 366,000
Area of leased property (in square feet) | ft²							19,467				19,467
Beijing JiYa Semiconductor Material Co., Ltd Investment
Related Party Transaction [Line Items]
Percentage of ownership, consolidated method (in hundredths)														39.00%	46.00%
Equity investment entity | Raw materials sales to related party | Accounts receivable | Beijing JiYa Semiconductor Material Co., Ltd
Related Party Transaction [Line Items]
Amounts receivable from related party							$ 0				$ 0		$ 12,000
Equity investment entity | Raw material agency sales agreement | Other income (expense), net [Member] | Nanjing JinMei Gallium Co., Ltd
Related Party Transaction [Line Items]
Other income from related party							0	$ 0			0	$ 0
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							163,000				163,000		0
Emei Shan Jiamei 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							0				0		0
Xilingol Tongli Germanium Co. Ltd | Raw materials purchases from related party | Accounts payable | Beijing Tongmei Xtal Technology
Related Party Transaction [Line Items]
Amount payable to related party							$ 0				$ 0		0
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				22,081
Lease term							10 years				10 years
Annual lease payment											$ 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]
Amount of transaction					$ 768,000
Number of installments | installment					3
Amount payable to related party							$ 302,000				$ 302,000		285,000
Interest rate (as a percent)					4.90%
Repayment of related party notes receivable											501,000
Executive officer | Related party loan | Beijing BoYu Semiconductor Vessel Craftwork Technology Co
Related Party Transaction [Line Items]
Amount of transaction		$ 141,000	$ 146,000	$ 291,000		$ 177,000
Interest rate (as a percent)		2.75%	2.75%	2.75%		2.75%
Repayment of related party notes receivable										$ 180,000
Executive officer | Related party loan | Other assets | Beijing BoYu Semiconductor Vessel Craftwork Technology Co
Related Party Transaction [Line Items]
Related party notes receivable - current							618,000				618,000		$ 449,000
3rd party investor | Beijing BoYu Semiconductor Vessel Craftwork Technology Co
Related Party Transaction [Line Items]
Revenue from related parties							$ 37,000	$ 0			$ 300,000	$ 100,000
Raised additional capital	$ 2,000,000
Percentage ownership from issuance of shares	10.00%

Investments in Privately-Held_3

Investments in Privately-Held Raw Material Companies (Details)	Jun. 15, 2018USD ($)installment	Nov. 02, 2017USD ($)	Aug. 31, 2020USD ($)	Jul. 31, 2020USD ($)	Apr. 30, 2020USD ($)	May 31, 2019USD ($)	Sep. 30, 2018USD ($)employeeentity	Sep. 30, 2020USD ($)employee	Sep. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Sep. 30, 2020USD ($)entityemployee	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Jun. 01, 2019USD ($)	Apr. 30, 2019	Mar. 11, 2019	Mar. 10, 2019	Aug. 31, 2018	Jun. 14, 2018	Nov. 01, 2017
Summary of investments
Investments, equity method								$ 5,826,000			$ 5,826,000		$ 5,961,000
Proceeds from sale of previously consolidated subsidiary shares										$ 366,000	366,000
Gain on deconsolidation										175,000		$ 175,000
Additional percentage of ownership, consolidated method							2
Payment of first installment												262,000
Noncontrolling interests								6,498,000			6,498,000		4,877,000
Remainder portion of payment								49,000			49,000		151,000
Number of persons on board | employee							1
Net income attributable to noncontrolling interests								490,000	$ 403,000		1,483,000	771,000
Impairment charge								0	0	$ 1,100,000	$ 0	1,100,000
Impaired entities | entity											1
Joint Ventures
Summary of investments
Number of consolidated joint ventures | entity							3
Income from consolidated joint ventures								1,800,000	1,100,000		$ 4,300,000	2,600,000
Net income attributable to noncontrolling interests								500,000	400,000		1,500,000	800,000
Net income (loss) from joint ventures attributable to parent								1,300,000	$ 700,000		2,800,000	$ 1,800,000
Other assets
Summary of investments
Investments, equity method								5,800,000			$ 5,800,000		6,000,000
Xilingol Tongli Germanium Co. Ltd Investment
Summary of investments
Direct minority investments not consolidated | entity											1
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								$ 1,509,000			$ 1,509,000		1,326,000
Percentage of ownership, equity method (in hundredths)								46.00%			46.00%
Beijing JiYa Semiconductor Material Co., Ltd Investment | Beijing JiYa Semiconductor Material Co., Ltd Investment
Summary of investments
Investments, equity method								$ 1,192,000			$ 1,192,000		1,621,000
Percentage of ownership, equity method (in hundredths)								39.00%			39.00%
Xilingol Tongli Germanium Co. Ltd Investment | Xilingol Tongli Germanium Co. Ltd Investment
Summary of investments
Investments, equity method								$ 0			$ 0
Percentage of ownership, equity method (in hundredths)								25.00%			25.00%
Xiaoyi XingAn Gallium Co., Ltd. | Xiaoyi XingAn Gallium Co., Ltd.
Summary of investments
Investments, consolidated method								$ 2,605,000			$ 2,605,000		2,367,000
Percentage of ownership, equity method (in hundredths)								25.00%			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								$ 520,000			$ 520,000		647,000
Percentage of ownership, equity method (in hundredths)								25.00%			25.00%
Beijing JiYa Semiconductor Material Co., Ltd Investment
Summary of investments
Percentage of ownership, consolidated method (in hundredths)																39.00%	46.00%
Beijing JiYa Semiconductor Material Co., Ltd Investment | Beijing JiYa Semiconductor Material Co., Ltd Investment
Summary of investments
Percentage of ownership, consolidated method (in hundredths)																39.00%	46.00%
Chaoyang JinMei Gallium Co., Ltd[member]
Summary of investments
Percentage of ownership, consolidated method (in hundredths)			91.50%	100.00%
Nanjing JinMei Gallium Co., Ltd Investment
Summary of investments
Percentage of ownership, consolidated method (in hundredths)						100.00%									97.00%
Nanjing JinMei Gallium Co., Ltd
Summary of investments
Number of new board representatives | employee											2
Beijing Boyu Semiconductor Vessel Craftwork Technology Co Ltd
Summary of investments
Number of persons on board | employee								2			2
Majority-Owned Subsidiaries
Summary of investments
Investments, consolidated method								$ 3,758,000			$ 3,758,000		3,758,000
Nanjing JinMei Gallium Co., Ltd Investment
Summary of investments
Investments, consolidated method								$ 592,000			$ 592,000		592,000
Additional percentage of ownership, consolidated method	12					3
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			$ 29,000	$ 73,000	262,000
Payment of second installment						1,200,000
Noncontrolling interests														$ 0
Remainder portion of payment						$ 49,000
Nanjing JinMei Gallium Co., Ltd Investment | Nanjing JinMei Gallium Co., Ltd Investment
Summary of investments
Percentage of ownership, consolidated method (in hundredths)								100.00%			100.00%							95.00%	83.00%
Chaoyang JinMei Gallium Co., Ltd[member]
Summary of investments
Investments, consolidated method								$ 1,820,000			$ 1,820,000		1,820,000
Percentage Of Ownership Interest Sold			8.50%
Proceeds from sale of previously consolidated subsidiary shares			$ 396,000
Additional percentage of ownership, consolidated method			8.5
Purchase of subsidiary shares from noncontrolling interest			$ 396,000
Chaoyang JinMei Gallium Co., Ltd[member] | Chaoyang JinMei Gallium Co., Ltd[member]
Summary of investments
Percentage of ownership, consolidated method (in hundredths)			91.50%	100.00%				91.50%			91.50%
Percentage Of Ownership Interest Sold			8.50%
Proceeds from sale of previously consolidated subsidiary shares			$ 396,000
Beijing JiYa Semiconductor Material Co., Ltd Investment | Beijing JiYa Semiconductor Material Co., Ltd Investment
Summary of investments
Percentage of ownership, consolidated method (in hundredths)								46.00%			46.00%
Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd Investment
Summary of investments
Investments, consolidated method								$ 1,346,000			$ 1,346,000		$ 1,346,000
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%			63.00%									70.00%

Investments in Privately-Held_4

Investments in Privately-Held Raw Material Companies - Gain on Deconsolidation (Details) - USD ($)	3 Months Ended	9 Months Ended
	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Mar. 12, 2019
Investments in Privately-Held Raw Material Companies
Fair value of the consideration received	$ 366,000	$ 366,000
Fair value of the retained investment in Beijing JiYa Semiconductor Material Co., Ltd.	2,040,000			$ 2,040,000
Carrying value of non-controlling interest, net of accumulated other comprehensive income attributable to subsidiary	617,000
Derecognition of Beijing JiYa Semiconductor Material Co., Ltd.'s net asset	(2,848,000)
Gain recognized on deconsolidation of Beijing JiYa Semiconductor Material Co., Ltd.	175,000		$ 175,000
Carrying value of retained noncontrolling investment	(1,559,000)
Gain on retained noncontrolling investment due to remeasurement	$ 481,000

Investments in Privately-Held_5

Investments in Privately-Held Raw Material Companies - Minority Investment Entities (Details) - Five Minority Investments - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Summarized income information of all the minority investment entities that are not consolidated and accounted for under the equity method [Abstract]
Net revenue	$ 5,052,000	$ 3,713,000	$ 12,610,000	$ 14,713,000
Gross profit (loss)	918,000	309,000	2,944,000	1,423,000
Operating (loss)	136,000	(436,000)	598,000	(1,857,000)
Net income (loss)	7,000	(502,000)	(151,000)	(2,518,000)
Minority investment entities
Entity portion of loss from unconsolidated equity method investments, including impairment charges	$ 45,000	$ 200,000	$ 200,000	$ 1,700,000

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended		12 Months Ended	48 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2015	Dec. 31, 2019	Oct. 27, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	$ 194,054	$ 192,190	$ 192,762	$ 195,655	$ 195,981	$ 194,532	$ 192,762	$ 194,532
Common stock options exercised	624	72	441	35	232
Purchase of subsidiary shares from noncontrolling interest					(413)
Sale of subsidiary shares to noncontrolling interests	396
Reclassification out of accumulated other comprehensive income and non-controlling interest upon the deconsolidation of a subsidiary						(617)		(617)
Stock-based compensation	648	641	643	583	568	558
Net income (loss)	1,481	959	217	(495)	1,738	(1,023)	2,657	220
Net dividend declared by joint ventures		(89)
Other comprehensive income (loss)	4,689	281	(1,873)	(4,324)	(2,451)	2,531
Balance, end of period	201,892	194,054	192,190	191,454	195,655	195,981	201,892	191,454		$ 192,762
Reclassification adjustment from AOCI	0			0			0	0
Stock repurchase program, authorized amount											$ 5,000
Shares repurchased (in shares)									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						2,700
Preferred Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	3,532	3,532	3,532	3,532	3,532	3,532	3,532	3,532
Balance, end of period	3,532	3,532	3,532	3,532	3,532	3,532	3,532	3,532		$ 3,532
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	41	41	41	40	40	40	41	40
Balance, end of period	41	41	41	40	40	40	41	40		41
Additional Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	238,754	238,041	236,957	235,702	234,976	234,418	236,957	234,418
Common stock options exercised	624	72	441	35	232
Purchase of subsidiary shares from noncontrolling interest					(74)
Sale of subsidiary shares to noncontrolling interests	396
Stock-based compensation	648	641	643	583	568	558
Balance, end of period	240,422	238,754	238,041	236,320	235,702	234,976	240,422	236,320		236,957
Accumulated Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(47,600)	(47,961)	(47,783)	(44,836)	(46,287)	(45,183)	(47,783)	(45,183)
Net income (loss)	991	361	(178)	(898)	1,451	(1,104)
Balance, end of period	(46,609)	(47,600)	(47,961)	(45,734)	(44,836)	(46,287)	(46,609)	(45,734)		(47,783)
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(6,365)	(6,637)	(4,862)	(3,130)	(733)	(1,972)	(4,862)	(1,972)
Reclassification out of accumulated other comprehensive income and non-controlling interest upon the deconsolidation of a subsidiary						(1,150)
Other comprehensive income (loss)	4,373	272	(1,775)	(4,110)	(2,397)	2,389
Balance, end of period	(1,992)	(6,365)	(6,637)	(7,240)	(3,130)	(733)	(1,992)	(7,240)		(4,862)
AXT, Inc. Stockholders' Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	188,362	187,016	187,885	191,308	191,528	190,835	187,885	190,835
Common stock options exercised	624	72	441	35	232
Purchase of subsidiary shares from noncontrolling interest					(74)
Sale of subsidiary shares to noncontrolling interests	396
Reclassification out of accumulated other comprehensive income and non-controlling interest upon the deconsolidation of a subsidiary						(1,150)
Stock-based compensation	648	641	643	583	568	558
Net income (loss)	991	361	(178)	(898)	1,451	(1,104)
Other comprehensive income (loss)	4,373	272	(1,775)	(4,110)	(2,397)	2,389
Balance, end of period	195,394	188,362	187,016	186,918	191,308	191,528	195,394	186,918		187,885
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	5,692	5,174	4,877	4,347	4,453	3,697	4,877	3,697
Purchase of subsidiary shares from noncontrolling interest					(339)
Reclassification out of accumulated other comprehensive income and non-controlling interest upon the deconsolidation of a subsidiary						533
Net income (loss)	490	598	395	403	287	81
Net dividend declared by joint ventures		(89)
Other comprehensive income (loss)	316	9	(98)	(214)	(54)	142
Balance, end of period	$ 6,498	$ 5,692	$ 5,174	$ 4,536	$ 4,347	$ 4,453	$ 6,498	$ 4,536		$ 4,877

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 648	$ 583	$ 1,932	$ 1,709
Net effect on net income	648	583	1,932	1,709
Cost of Revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	28	31	83	92
Selling, General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	496	433	1,480	1,296
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 124	$ 119	$ 369	$ 321

Stock-Based Compensation - Opti

Stock-Based Compensation - Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Aggregate Intrinsic Value [Abstract]
Closing price (in dollars per share)	$ 6.12		$ 6.12
Options
Number of Options Outstanding [Roll Forward]
Options outstanding, beginning of period (in shares)			2,953,000
Granted (in shares)	0	0	0	0
Exercised (in shares)			(460,000)
Canceled and expired (in shares)			(162,000)
Options outstanding, end of period (in shares)	2,331,000		2,331,000		2,953,000
Options vested and unvested options expected to vest, net of forfeitures, end of period (in shares)	2,313,000		2,313,000
Options exercisable, end of period (in shares)	1,703,000		1,703,000
Weighted-average Exercise Price [Roll Forward]
Options outstanding, beginning of period (in dollars per share)			$ 4
Exercised (in dollars per share)			2.47
Canceled and expired (in dollars per share)			5.83
Options outstanding, end of period (in dollars per share)	$ 4.18		4.18		$ 4
Options vested and unvested options expected to vest, net of forfeitures (in dollars per share)	4.18		4.18
Options exercisable, end of period (in dollars per share)	$ 4.20		$ 4.20
Weighted average Remaining Contractual Life [Abstract]
Options outstanding			5 years 10 months 20 days		5 years 11 months 12 days
Options vested and unvested options expected to vest, net of forfeitures, end of period			5 years 10 months 13 days
Option exercisable, end of period			4 years 10 months 17 days
Aggregate Intrinsic Value [Abstract]
Options outstanding, beginning of period			$ 3,040
Options outstanding, end of period	$ 5,061		5,061		$ 3,040
Options vested and expected to vest, end of period	5,012		5,012
Options exercisable, end of period	$ 3,675		$ 3,675

Stock-Based Compensation - RSU

Stock-Based Compensation - RSU (Details) $ / shares in Units, shares in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)$ / sharesshares
Weighted Average Grant Date Fair Value [Roll Forward]
Unrecognized compensation expense related to restricted stock awards | $	$ 3,000,000
Weighted average remaining contractual terms	1 year 1 month 6 days
Restricted Stock Awards
Shares [Roll Forward]
Non-vested, beginning of period (in shares) | shares	939
Granted (in shares) | shares	55
Vested (in shares) | shares	(127)
Forfeited (in shares) | shares	(12)
Non-vested, end of period (in shares) | shares	855
Weighted Average Grant Date Fair Value [Roll Forward]
Non-vested, beginning of period (in dollars per share) | $ / shares	$ 5.02
Granted (in dollars per share) | $ / shares	5.21
Vested (in dollars per share) | $ / shares	6
Forfeited (in dollars per share) | $ / shares	5.69
Non-vested, end of period (in dollars per share) | $ / shares	$ 4.88
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation costs related to unvested stock options not yet recognized | $	$ 1,000,000
Value of estimated forfeitures | $	$ 80,000
Weighted-average period of amortization	2 years 6 months

Net Income (Loss) Per Share (De

Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Numerator:
Net income (loss) attributable to AXT, Inc.	$ 991	$ (898)	$ 1,174	$ (551)
Less: Preferred stock dividends	(44)	(44)	(132)	(132)
Net income (loss) available to common stockholders	$ 947	$ (942)	$ 1,042	$ (683)
Weighted-average number of common shares outstanding:
Denominator for basic net income (loss) per share - weighted-average common shares	40,152,000	39,466,000	39,978,000	39,438,000
Effect of dilutive securities:
Denominator for dilutive net income (loss) per common shares	40,979,000	39,466,000	40,688,000	39,438,000
Net income (loss) attributable to AXT, Inc. per common share:
Basic	$ 0.02	$ (0.02)	$ 0.03	$ (0.02)
Diluted	$ 0.02	$ (0.02)	$ 0.03	$ (0.02)
Preferred stock, shares issued (in shares)	883,000		883,000		883,000
Preferred stock, shares outstanding (in shares)	883,000		883,000		883,000
Preferred stock, par value (in dollars per share)	$ 0.001		$ 0.001		$ 0.001
Preferred stock, value	$ 3,532		$ 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		$ 4
Options
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)	1,036,000	2,523,000	1,298,000	2,523,000
Restricted Stock Awards
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	698,000	347,000	698,000
Options
Effect of dilutive securities:
Effect of dilutive securities (in shares)	575,000		510,000
Restricted Stock Awards
Effect of dilutive securities:
Effect of dilutive securities (in shares)	252,000		200,000

Segment Information and Forei_3

Segment Information and Foreign Operations - Product Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue by product type
Revenue	$ 25,469	$ 19,841	$ 68,326	$ 64,846
Substrates
Revenue by product type
Revenue	20,311	15,959	54,066	53,324
Raw materials and others
Revenue by product type
Revenue	$ 5,158	$ 3,882	$ 14,260	$ 11,522

Segment Information and Forei_4

Segment Information and Foreign Operations - Segment and Geographical Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)segment	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)
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	$ 25,469	$ 19,841	$ 68,326	$ 64,846
Long-lived assets by geographic region, net of depreciation:
Long-lived assets	110,997		110,997		$ 100,341
Reportable Geographical Components | China
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	10,568	5,117	23,045	21,870
Long-lived assets by geographic region, net of depreciation:
Long-lived assets	110,140		110,140		99,272
Reportable Geographical Components | Taiwan
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	3,333	4,399	12,908	12,062
Reportable Geographical Components | Japan
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	2,233	1,339	5,265	4,641
Reportable Geographical Components | Asia Pacific (excluding China, Taiwan, and Japan)
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	1,446	2,234	4,503	6,156
Reportable Geographical Components | Europe (primarily Germany)
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	4,689	4,737	15,017	13,752
Reportable Geographical Components | North America (primarily the United States)
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	3,200	$ 2,015	7,588	$ 6,365
Long-lived assets by geographic region, net of depreciation:
Long-lived assets	$ 857		$ 857		$ 1,069

Segment Information and Forei_5

Segment Information and Foreign Operations - Concentration of Credit Risk (Details) - customer	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenues
Revenue, Major Customer [Line Items]
Number of customers representing significant share	0	1	2	2
Percentage share generated by major customers	10.00%
Accounts Receivable
Revenue, Major Customer [Line Items]
Number of customers representing significant share			2		3
Landmark | Revenues
Revenue, Major Customer [Line Items]
Percentage share generated by major customers		16.00%	11.00%	10.00%
Haisi Optoelectronics | Revenues
Revenue, Major Customer [Line Items]
Percentage share generated by major customers				14.00%
Osram Opto [Member] | Revenues
Revenue, Major Customer [Line Items]
Percentage share generated by major customers			10.00%
Major Customer One | Accounts Receivable
Revenue, Major Customer [Line Items]
Percentage share generated by major customers			10.00%		14.00%
Major Customer Two | Accounts Receivable
Revenue, Major Customer [Line Items]
Percentage share generated by major customers			10.00%		13.00%
Major Customer Three | Accounts Receivable
Revenue, Major Customer [Line Items]
Percentage share generated by major customers					12.00%
Top Five Major Customers | Revenues
Revenue, Major Customer [Line Items]
Number of customers representing significant share	5	5	5	5
Percentage share generated by major customers	29.00%	40.00%	33.00%	41.00%

Commitments and Contingencies_2

Commitments and Contingencies (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)ft²	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)ft²	Sep. 30, 2019USD ($)
Product Warranty [Abstract]
Period of warranty			12 months
Change in warranty accrual [Roll Forward]
Beginning accrued product warranty	$ 352	$ 353	$ 387	$ 236
Accruals for warranties issued	195	146	384	388
Adjustments related to pre-existing warranties including expirations and changes in estimates	171	27	99	175
Cost of warranty repair	(189)	(183)	(341)	(456)
Ending accrued product warranty	$ 529	$ 343	$ 529	$ 343
Leases
Area of property under long-term operating lease (in square feet) | ft²	19,467		19,467
Cross License Agreement
Preferred label sub abstract as Contractual Obligations
Term of Agreement			10 years
Dingxing
Leases
Total investment agreement value	$ 90,000		$ 90,000
Kazuo
Leases
Total investment agreement value	15,000		15,000
Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd Investment | Kazuo
Leases
Total investment agreement value	$ 8,000		$ 8,000

Other Income (Expense), Net (De

Other Income (Expense), Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Other Income (Expense), Net
Income from government grants	$ 0		$ 3,000
Foreign exchange gain (loss)	$ (135,000)	$ 165,000	$ (126,000)	$ 85,000

Income Taxes - (Details)

Income Taxes - (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2020USD ($)
Income Taxes
Deferred tax assets	$ 0	$ 0
Unrecognized tax benefit interest and penalties expense		0
Unrecognized tax benefits accrued interest and penalties	0	0
Federal income tax benefit or expense	$ 0	$ 0

Revenue - Revenue Recognition (

Revenue - Revenue Recognition (Details)	9 Months Ended
	Sep. 30, 2020
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales commissions benefit period	1 year

Revenue - Contract Balances (De

Revenue - Contract Balances (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Revenue
Contract liabilities	$ (494)	$ (396)
Revenue recognized, included in contract assets	$ 8,000	$ 242,000

Revenue - Disaggregated Revenue

Revenue - Disaggregated Revenue (Details)	9 Months Ended
	Sep. 30, 2020segment
Revenue
Number of operating segments	1

Bank Loans and Line of Credit (

Bank Loans and Line of Credit (Details) - USD ($) $ in Thousands

Aug. 09, 2020

Sep. 12, 2019

Aug. 09, 2019

Nov. 06, 2018

Oct. 31, 2020

Mar. 31, 2020

Feb. 29, 2020

Sep. 30, 2020

Sep. 30, 2019

Jul. 31, 2020

Feb. 05, 2020

Feb. 04, 2020

Dec. 31, 2019

Debt Instrument [Line Items]

Proceeds from lines of credit

$ 3,380

$ 5,760

Bank loan

$ 3,380

$ 5,747

Interest rate

3.85%

Renewal period

6 months

Subsequent Event

Debt Instrument [Line Items]

Interest rate

4.70%

Combined loan totals

$ 5,600

Renewal period

6 months

Additional loan borrowed

$ 2,700

Repayments of loan

$ 5,600

Lines OF Credit, Current

Debt Instrument [Line Items]

Letters of credit outstanding

$ 2,900

Bank Of China | Secured Debt | Beijing Tongmei Xtal Technology

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 5,800

Annual interest rate at end

4.70%

Proceeds from credit facility

$ 2,800

$ 2,800

Repayments of loan

$ 5,900

Bank Of China | Secured Debt | Beijing Tongmei Xtal Technology | Prime Rate

Debt Instrument [Line Items]

Variable rate spread (as a percent)

0.40%

ICBC | Secured Debt | Lines OF Credit, Current

Debt Instrument [Line Items]

Letters of credit outstanding

$ 400

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%

Proceeds from lines of credit

$ 400

ICBC | Secured Debt | Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd Investment | Prime Rate

Debt Instrument [Line Items]

Variable rate spread (as a percent)

0.15%

Wells Fargo Bank | Secured Debt

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 10,000

$ 7,000

$ 10,000

Letters of credit outstanding

$ 0

Wells Fargo Bank | Secured Debt | LIBOR

Debt Instrument [Line Items]

Variable rate spread (as a percent)

2.00%

2.50%

Wells Fargo Bank | Letter of credit

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 1,000

Leases (Details)

Leases (Details) $ in Thousands	1 Months Ended	9 Months Ended
	May 31, 2020	Sep. 30, 2020USD ($)ft²	Dec. 31, 2019USD ($)	Jan. 01, 2019USD ($)
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
Operating lease right-of-use assets		2,702	$ 2,938
Operating lease liability		$ 2,836
Lease, Practical Expedients, Package [true false]		true
ASU 2016-02
Leases
Operating lease right-of-use assets				$ 1,100
Operating lease liability				$ 1,100

Leases - Maturities of Operatin

Leases - Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Future minimum lease payments
2020	$ 129
2021	555
2022	571
2023	562
2024	274
Thereafter	1,252
Total minimum lease payments	3,343
Less: Interest	(507)
Present value of lease obligations	$ 2,836
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiablitiesCurrent
Less: Current portion, included in accrued liabilities	$ (421)	$ (319)
Long-term portion of lease obligations	$ 2,415	$ 2,695

Leases - Weighted-Average Remai

Leases - Weighted-Average Remaining Lease Term and Discount Rate (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Leases
Weighted-average remaining lease term (years)	7 years 4 months 2 days		7 years 11 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	$ 324	$ 159
Leased assets obtained in exchange for new operating lease liabilities		$ 2,072

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lease expense
Operating lease	$ 128	$ 106	$ 383	$ 229
Short-term lease expense	27	14	61	42
Total	$ 155	$ 120	$ 444	$ 271