Phototransistor of the type having an emitter-base heterojunction

US4620210A · kind A · utility

Inventors

• Andre Scavennec · Paris, FR
• David Ankri · Jouy-le-Moutier, FR

Key dates

• Filing date: Aug 17, 1984
• Grant date: Oct 28, 1986
• Expiry date: Aug 17, 2004

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10F30/245

Abstract

A phototransistor comprising a substrate (9), a collector layer (2), a base layer (3), and an emitter layer (4) is disclosed. The base layer (3) is of a first composite III-V semiconductor material with a first type of doping and the emitter layer (4) is of a second composite III-V semiconductor material. A diffusion well (6), of the first type of doping extends on a main part of the emitter layer (4) down to the base layer. The remaining part of the emitter layer (4) is of a second type of doping. The main part of the emitter layer (4) has an area at least 100 times larger than the area of the remaining part. A contact layer with the second type of doping is deposited on the remaining part of the emitter layer (4) with an emitter contact on the contact layer, and a base contact on an extremity of the diffusion well (6). Such a phototransistor thus comprises a heterojunction transistor under the emitter contact and a homojunction photodiode under the diffusion well (6), and the diffusion well (6) is transparent in most of its thickness to light radiation to be detected.