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:
Oct. 15, 1991
Filed:
Feb. 12, 1991
Toshitaka Torikai, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
A planar heterojunction avalanche photodiode (APD) having a first semiconductor layer of a first conductivity type for generating carriers by absorbing light, a second semiconductor layer of the same first conductivity type having an impurity concentration which decreases with the distance from the first semiconductor layer and a bandgap greater than that of the first semiconductor layer for avalanche-multiplying the carriers injected from the first semiconductor layer. A first semiconductor region of a second conductivity type is diffused in the second semiconductor layer at a prescribed depth from the upper surface of the second semiconductor layer thus forming a stepwise p-n junction. A guard-ring of the second conductivity type is formed in the second semiconductor layer to overlap the circumferential part of the first semiconductor region and forming a linearly graded p-n junction with the second semiconductor layer in a position closer to the first semiconductor layer than the stepwise p-n junction.