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:
Jan. 08, 1991
Filed:
Jan. 17, 1989
Shuichi Miura, Kawasaki, JP;
Takashi Mikawa, Tokyo, JP;
Haruhiko Kuwatsuka, Yokohama, JP;
Nami Yasuoka, Hachioji, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
An APD includes a substrate formed of n.sup.+ -type Al.sub.x Ga.sub.1-x Sb or Al.sub.x Ga.sub.1-x Sb.sub.y As.sub.1-y semiconductor, whose aluminum content ratio x is typically within a range from 0.1 to 0.3. A light absorbing layer is formed of an-type GaSb semiconductor on the substrate. An avalanche multiplication layer is formed of n-type Al.sub.x Ga.sub.1-x Sb or Al.sub.x Ga.sub.1-x Sb.sub.y As.sub.1-y semiconduct, whose aluminum content ratio x is from 0.02 to 0.1, typically 0.065, so that an ionization rate ratio of positive and negative carriers is essentially maximized by a resonant impact ionization phenomenon. A p.sup.+ -region is formed as a surface layer of n-type Al.sub.x Ga.sub.1-x Sb or Al.sub.x Ga.sub.1-x Sb.sub.y As.sub.1-y semiconductor on the avalanche multiplication layer or directly in the avalanche multiplication layer so as to form a pn junction. Electrodes are formed on the p-type region and the substrate so as to apply a bias voltage to the APD. A light to be detected is injected through the substrate via an opening in the substrate electrode, while producing no carriers therein, into the light absorbing layer. The avalanche multiplication layer generates resonant impact ionization with only the positive carriers from the light absorbing layer, so that low noise and fast operation of the APD is achieved. Furthermore, the APD structure of the invention allows for easy design of an APD.