Abstract: One aspect of the present invention is directed to a heterojunction bipolar transistor (HBT) comprising: a substrate; a buffer layer of undoped semiconductor material; a sub-collector layer; a collector layer; a base layer; an emitter layer; a emitter cap layer; and a contact layer; wherein a planar doping sheet is included between the substrate layer and the collector layer; and a collector electrode in electrical connection to said collector layer; a base electrode in electrical connection with said base layer; and an emitter electrode provided in electrical connection to said emitter layer.
Type:
Grant
Filed:
September 13, 2005
Date of Patent:
July 8, 2008
Assignee:
Sumika Electronic Materials, Inc.
Inventors:
Kenneth Lee Campman, Brian Anthony Novak