Net Loss Per Share - Reconciliation of Basic and Diluted Net Income (Loss) per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Numerator:
Net loss attributable to AXT, Inc.	$ (2,083)	$ (3,348)
Less: Preferred stock dividends	(44)	(44)
Net loss available to common stockholders	$ (2,127)	$ (3,392)
Denominator:
Denominator for basic net income (loss) per share - weighted-average common shares	42,987	42,498
Effect of dilutive securities:
Denominator for dilutive net income (loss) per common shares	42,987	42,498
Net loss attributable to AXT, Inc. per common share:
Basic	$ (0.05)	$ (0.08)
Diluted	$ (0.05)	$ (0.08)
Common stock options
Net loss attributable to AXT, Inc. per common share:
Securities excluded from diluted net income (loss) per share as the impact is anti-dilutive (in shares)	1,189	1,203
Restricted stock awards
Net loss attributable to AXT, Inc. per common share:
Securities excluded from diluted net income (loss) per share as the impact is anti-dilutive (in shares)	1,401	1,081