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                                                                     EXHIBIT 5.1



August 29, 2000

Securities and Exchange Commission
450 Fifth Street, N.W.
Washington, D.C.  20549

        Re:    AXT, INC.
               REGISTRATION STATEMENT ON FORM S-3

Ladies and Gentlemen:

        As counsel to AXT, Inc., a Delaware corporation (the "Company"), we are
rendering this opinion in connection with a proposed sale of those certain
shares of the Company's newly-issued Common Stock, par value $0.001, as set
forth in the registration statement on Form S-3 (the "Registration Statement")
to which this opinion is being filed as Exhibit 5.1 (the "Shares").

        We have examined such instruments, documents and records as we deemed
relevant and necessary for the basis of our opinion hereinafter expressed. In
such examination, we have assumed the genuineness of all signatures and the
authenticity of all documents submitted to us as originals and the conformity to
the originals of all documents submitted to us as copies.

        Based on such examination, we are of the opinion that the Shares of the
Company identified in the above-referenced Registration Statement will be, upon
effectiveness of the Registration Statement and receipt by the Company of
payment therefor, validly authorized, legally issued, fully paid and
nonassessable.

        We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement referred to above and the use of our name wherever it
appears in said Registration Statement, including the Prospectus constituting a
part thereof, as originally filed or as subsequently amended.


                                        Respectfully submitted,

                                        /s/ Gray Cary Ware & Freidenrich LLP

                                        GRAY CARY WARE & FREIDENRICH LLP