AXTI AXT Inc

The Board of Directors recommends you vote FOR the following: 1. To elect Two (2) Class I Directors to hold office for a three-year term and until their respective successors are elected and qualified. Class I Directors: 01) Dr. Morris S. Young 02) Dr. David C. Chang The Board of Directors recommends you vote FOR proposals 2 and 3. 2. To approve, on an advisory basis, the compensation of AXT's named executive officers. 3. To ratify the appointment of BPM LLP as AXT's independent registered public accounting firm for the fiscal year ending December 31, 2020. NOTE: Such other business as may properly come before the meeting or any adjournment thereof. E99790-P34637 Voting Items

VOTE BY INTERNET - www.proxyvote.com Use the Internet to transmit your voting instructions and for electronic delivery of information up until 11:59 P.M. Eastern Time the day before the cut-off date or meeting date. Have your proxy card in hand when you access the web site and follow the instructions to obtain your records and to create an electronic voting instruction form. c/o BROADRIDGE P.O. BOX 1342 BRENTWOOD, NY 11717 ELECTRONIC DELIVERY OF FUTURE PROXY MATERIALS If you would like to reduce the costs incurred by our company in mailing proxy materials, you can consent to receiving all future proxy statements, proxy cards and annual reports electronically via e-mail or the Internet. To sign up for electronic delivery, please follow the instructions above to vote using the Internet and, when prompted, indicate that you agree to receive or access proxy materials electronically in future years. VOTE BY PHONE - 1-800-690-6903 Use any touch-tone telephone to transmit your voting instructions up until 11:59 P.M. Eastern Time the day before the cut-off date or meeting date. Have your proxy card in hand when you call and then follow the instructions. VOTE BY MAIL Mark, sign and date your proxy card and return it in the postage-paid envelope we have provided or return it to Vote Processing, c/o Broadridge, 51 Mercedes Way, Edgewood, NY 11717. TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: E99782-P34637 KEEP THIS PORTION FOR YOUR RECORDS DETACH AND RETURN THIS PORTION ONLY THIS PROXY CARD IS VALID ONLY WHEN SIGNED AND DATED. AXT, INC. The Board of Directors recommends you vote FOR the following: For Withhold For All AllAllExcept To withhold authority to vote for any individual nominee(s), mark "For All Except" and write the number(s) of the nominee(s) on the line below. ! ! ! 1. To elect Two (2) Class I Directors to hold office for a three-year term and until their respective successors are elected and qualified. Class I Directors: 01) Dr. Morris S. Young 02) Dr. David C. Chang The Board of Directors recommends you vote FOR proposals 2 and 3. For Against Abstain ! ! ! ! ! ! 2. To approve, on an advisory basis, the compensation of AXT's named executive officers. 3. To ratify the appointment of BPM LLP as AXT's independent registered public accounting firm for the fiscal year ending December 31, 2020. NOTE: Such other business as may properly come before the meeting or any adjournment thereof. For address change/comments mark here. (see reverse for instructions) ! ! Yes ! No Please indicate if you plan to attend this meeting. Please sign exactly as your name(s) appear(s) hereon. When signing as attorney, executor, administrator, or other fiduciary, please give full title as such. Joint owners should each sign personally. All holders must sign. If a corporation or partnership, please sign in full corporate or partnership name by authorized officer. Signature [PLEASE SIGN WITHIN BOX] Date Signature (Joint Owners) Date

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting: The Notice and Proxy Statement and Annual Report on Form 10-K are available at www.proxyvote.com. E99783-P34637 AXT, INC. Annual Meeting of Stockholders May 21, 2020 11:00 a.m. This proxy is solicited by the Board of Directors The undersigned hereby constitutes and appoints Dr. Morris S. Young and Gary L. Fischer and each of them, as his or her true and lawful agents and proxies with full power of substitution, and hereby authorizes them to represent the undersigned and to vote all of the shares of common stock in AXT, Inc., which the undersigned is entitled to vote, at the 2020 Annual Meeting of Stockholders to be held at 4281 Technology Drive, Fremont, California on May 21, 2020 at 11:00 a.m. Pacific Daylight Time, and at any adjournment thereof (1) as hereinafter specified upon the proposals listed and as more particularly described in AXT's proxy statement, receipt of which is hereby acknowledged, and (2) in their discretion upon such other matters as may properly come before the meeting. This proxy, when properly executed, will be voted in the manner directed herein. If no such direction is made, this proxy will be voted in accordance with the Board of Directors' recommendations. (If you noted any Address Change and/or Comments above, please mark corresponding box on the reverse side.) Continued and to be signed on reverse side Address change/comments: