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:
Jun. 04, 1996
Filed:
Jun. 05, 1995
Applicant:
Inventor:
Masao Obara, Machida, JP;
Assignee:
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Primary Examiner:
Int. Cl.
CPC ...
H01L / ; H01L / ;
U.S. Cl.
CPC ...
257197 ; 257198 ;
Abstract
An AlGaAs/GaAs heterojunction bipolar transistor in which a base doping concentration is set to be as very high as 5.times.10.sup.19 cm.sup.-3 or more to cause a band gap narrowing effect and to reduce a band gap difference by an amount corresponding to the band gap narrowing effect, an Al composition ratio, i.e., x in an Al.sub.x Ga.sub.1-x As material of an emitter layer is set to be less than 0.25, whereby an emitter resistance can be made small, an operating speed can be made fast and a current gain can be made high. Preferably, the base doping concentration is set to be 1.2.times.10.sup.20 cm.sup.-3 or more so that the operation speed can be made remarkably fast.