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:
May. 16, 1989
Filed:
Sep. 22, 1988
Tadashi Umeji, Kawasaki, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
A P-type epitaxial silicon layer is formed between an N-type epitaxial layer and a P.sup.+ -type semiconductor substrate. An impurity concentration profile is formed in at least one region of the P-type epitaxial silicon layer to decrease with an increase in distance from the substrate and toward the N-type epitaxial layer. A depletion layer is formed as a function region (P-N junction) between the P-type epitaxial silicon layer and the N-type epitaxial layer. Carriers are generated when light is incident on the depletion layer. Carriers are also generated in a region of the P-type layer deeper than the depletion layer. A self-electric field is formed in the P-type epitaxial silicon layer by the impurity concentration profile, which is lowest at the junction. The carriers generated in this manner are accelerated by the self-electric field and flow rapidly into the function region. As a result, an optical semiconductor device according to the present invention has good response characteristics.