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EXHIBIT 31.2

I, Donald L. Tatzin, certify that:



| | 1. |  | I have reviewed this Form 10-Q of AXT, Inc.;                                                                                                                                                                                                                                                              
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| | 2. |  | Based on my knowledge, this report does not contain any untrue
statement of a material fact or omit to state a material fact necessary
to make the statements made, in light of the circumstances under which
such statements were made, not misleading with respect to the period
covered by this report;
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| | 3. |  | Based on my knowledge, the financial statements, and other
financial information included in this report, fairly present in all
material respects the financial condition, results of operations and
cash flows of the registrant as of, and for, the periods presented in
this report;                   
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| | 4. |  | The registrants other certifying officer and I are responsible for
establishing and maintaining disclosure controls and procedures (as
defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the
registrant and have:                                                                               

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| |  | (a) Designed such disclosure controls and procedures, or caused such
disclosure controls and procedures to be designed under our
supervision, to ensure that material information relating to the
registrant, including its consolidated subsidiaries, is made known to
us by others within those entities, particularly during the period in
which this report is being prepared;         
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| |  | (b) Evaluated the effectiveness of the registrants disclosure
controls and procedures and presented in this report our conclusions
about the effectiveness of the disclosure controls and procedures, as
of the end of the period covered by this report based on such
evaluation; and                                                                                                    
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| |  | (c) Disclosed in this report any change in the registrants internal
control over financial reporting that occurred during the registrants
most recent fiscal quarter (the registrants fourth fiscal quarter in
the case of an annual report) that has materially affected, or is
reasonably likely to materially affect, the registrants internal
control over financial reporting; and



| | 5. |  | The registrants other certifying officer and I have disclosed,
based on our most recent evaluation of internal control over financial
reporting, to the registrants auditors and the audit committee of the
registrants board of directors (or persons performing the equivalent
functions):
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| |  | (a) All significant deficiencies and material weaknesses in the design
or operation of internal control over financial reporting which are
reasonably likely to adversely affect the registrants ability to
record, process, summarize and report financial information; and
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| |  | (b) Any fraud, whether or not material, that involves management or
other employees who have a significant role in the registrants
internal control over financial reporting.                                                                                               

Date: November 13, 2003

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|/s/  Donald L. Tatzin  
|Donald L. Tatzin       
|Chief Financial Officer