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:
Jun. 19, 1990
Filed:
Aug. 07, 1989
Takashi Mikawa, Tokyo, JP;
Takao Kaneda, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
An APD of the invention has its avalanche multiplication layer, made of a material which can cause a resonant impact ionization therein, between its window layer having a big band gap energy and light-absorbing layer having a band gap energy smaller than the window layer. The layout of the invention lowers field intensity in the light absorbing layer, thus, a dark current produced by a tunnel effect in the light absorbing layer is reduced. Because of great amount of ionization ratio in the resonant impact ionization phenomena, both excessive noise factor and the applied operating DC voltage to the APD can be much less than that of the prior art APD without employing the resonant impact ionization, as well as the operation speed can be increased. The reduced operation voltage protects unexpected local avalanche breakdown in the pn junction area, thus uniform and reliable avalanche multiplication is always initiated in the multiplication layer, resulting in reduction of dark current and allowing a voltage margin. For fabricating the APD, there is no difficult problem like the difficulty of doping n.sup.+ impurity in the p-type window layer in the prior art APD employing the resonant impact ionization. Excessive noise factor below 3, operation at 12.5 V, and operation at 10 GHZ are achieved.