**Exhibit 31.1**

 

**CERTIFICATIONPURSUANT TO**

**18 U.S.C.RULE 13a-14(a)/15d-14(a)**

**ASADOPTED PURSUANT TO**

**SECTION 302OF THE SARBANES-OXLEY ACT OF 2002**

 

I, Philip C.S. Yin,certify that:

 

1.            I have reviewed this quarterlyreport on Form 10-Q/A of AXT, Inc.;

 

2.            Based on my knowledge, this reportdoes not contain any untrue statement of a material fact or omit to state amaterial fact necessary to make the statements made, in light of thecircumstances under which such statements were made, not misleading with respectto the period covered by this report;

 

4.            The registrant’s other certifying officer(s) andI are responsible for establishing and maintaining disclosure controls andprocedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e))and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and15d-15(f)) for the registrant and have:

 

(a)           Designedsuch disclosure controls and procedures, or caused such disclosure controls andprocedures to be designed under our supervision, to ensure that materialinformation relating to the registrant, including its consolidatedsubsidiaries, is made known to us by others within those entities, particularlyduring the period in which this report is being prepared;

 

(b) Designed such internal control over financialreporting, or caused such internal control over financial reporting to bedesigned under our supervision, to provide reasonable assurance regarding thereliability of financial reporting and the preparation of financial statementsfor external purposes in accordance with generally accepted accountingprinciples;

 

(c) Evaluated the effectiveness of the registrant’sdisclosure controls and procedures and presented in this report our conclusionsabout the effectiveness of the disclosure controls and procedures, as of theend of the period covered by this report based on such evaluation; and

 

(d) Disclosed in this report any change in theregistrant’s internal control over financial reporting that occurred during theregistrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarterin the case of an annual report) that has materially affected, or is reasonablylikely to materially affect, the registrant’s internal control over financialreporting; and

 

5.            The registrant’s other certifyingofficer and I have disclosed, based on our most recent evaluation of internalcontrol over financial reporting, to the registrant’s auditors and the auditcommittee of the registrant’s board of directors (or persons performing theequivalent functions):

 

(a) All significant deficiencies and materialweaknesses in the design or operation of internal control over financialreporting which are reasonably likely to adversely affect the registrant’sability to record, process, summarize and report financial information; and

 

(b) Any fraud, whether or not material, thatinvolves management or other employees who have a significant role in theregistrant’s internal control over financial reporting.

 
| /s/ PHILIP C.S. YIN                               |   |
|---------------------------------------------------|--------|
| Philip C.S. Yin                                   |
| Chairman of the Board and Chief Executive Officer |
| May 21, 2008                                 |

 

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