Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2020	Aug. 01, 2020
Document And Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 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 Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		40,997,141
Entity Central Index Key	0001051627
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Amendment Flag	false