The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 20, 1991
Filed:
Jul. 09, 1990
Applicant:
Inventor:
Riichi Katoh, Yokohama, JP;
Assignee:
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Primary Examiner:
Int. Cl.
CPC ...
H01L / ; H01L / ;
U.S. Cl.
CPC ...
357 16 ; 357 34 ;
Abstract
A heterojunction bipolar transistor comprises an emitter layer made of a material having a band gap larger than that of a base layer and which includes a region subjected to a composition variation so that the band gap is made gradually smaller from inside of the emitter layer into inside of the base layer toward a base/collector junction direction. In the transistor, the emitter layer is made of an InP composition, the base layer is made of a gaInAsP composition which is lattice matched with the InP composition, and a composition ratio .beta. of P to As in a base/emitter junction satisfies an inequality relationship 0.3.ltoreq..beta..ltoreq.0.7.