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:
Feb. 17, 1998
Filed:
Mar. 14, 1996
Motoji Yagura, Tenri, JP;
John Kevin Twynam, Tenri, JP;
Hiroya Sato, Tenri, JP;
Toshiaki Kinosada, Izumi, JP;
Koken Yoshikawa, Ikoma, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
A hetero-junction bipolar transistor includes: a substrate; a first conductive type collector layer disposed on the substrate; a second conductive type base layer having an external base region; and a first conductive type emitter layer having a bandgap larger than the bandgap of the base layer disposed in this order, wherein the emitter layer includes a first emitter layer, an etching stop layer, and a second emitter layer disposed in this order starting from the substrate side; a base electrode is formed on the etching stop layer or the first emitter layer disposed on the external base region; a region of the first emitter layer on the base layer has a thickness such that the region is substantially depleted at all voltages applied when the transistor is normally operated; the second emitter layer has an electron affinity equal to or smaller than an electron affinity of the first emitter layer; and the etching stop layer has an electron affinity larger than the electron affinity of the first emitter layer, and has a thickness of approximately 3 nm.