| Document and Entity Information | Oct. 03, 2022 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Oct. 03, 2022 |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.001 par value |
| Trading Symbol | AXTI |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001051627 |
| Amendment Flag | false |
