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:
Jul. 19, 1994
Filed:
Mar. 05, 1992
Kouhei Morizuka, Yokohama, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
A high-cut-off frequency, high-speed HBT is obtained by suppressing the diffusion of impurities to the utmost by lowering a heat treatment temperature in the step subsequent to the formation of a high concentration base layer. A base electrode for a base layer is made of a metal or an intermetallic compound which extends the emitter layer to reach at least a part of the base layer. The metal or intermetallic compound forms Schottky barrier with an emitter layer having a wide forbidden width ,and ohmic contacts with the base layer with a narrow forbidden band. The barrier potential of the Schottky junction formed between the intermetallic compound or metal and the emitter layer is higher than the diffusion potential of a pn junction between the base layer and the emitter layer.