Patents by Inventor William U.-C. Liu

William U.-C. Liu has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Method for fabricating microwave heterojunction bipolar transistors with emitters designed for high power applications
    Patent number: 5389554
    Abstract: In one form of the invention, an emitter structure for a bipolar transistor is disclosed. The structure is comprised of an emitter layer 6 of Al.sub.x Ga.sub.1-x As, where x>0.4, abutting a base layer 8.
    Type: Grant
    Filed: November 30, 1993
    Date of Patent: February 14, 1995
    Assignee: Texas Instruments Incorporated
    Inventors: William U. C. Liu, Darrell G. Hill
  • 1/f noise reduction in heterojunction bipolar transistors
    Patent number: 5298439
    Abstract: A method of making a transistor comprising the steps of providing a structure having a collector layer 3, a base layer 5, and an emitter layer 7, one atop the other, forming a contact 9 on the emitter layer, removing a portion of the emitter layer to leave a relatively thick mesa region 13 with the contact thereon, a surrounding relatively thin ledge region 11 and an exposed portion of the base layer 5 and forming a contact on the exposed portion of the base layer 5. The emitter layer 7 is preferably GaInP, and preferably Ga.sub.x In.sub.1-x P, wherein x is in the range of approximately 0.50 to 0.52, and the base 5 is preferably GaAs. The ledge portion 11 has a thickness of about 700 Angstroms.
    Type: Grant
    Filed: December 31, 1992
    Date of Patent: March 29, 1994
    Assignee: Texas Instruments Incorporated
    Inventors: William U.-C. Liu, Shou-Kong Fan