Phototransistor device with fully depleted base region

摘要

A phototransistor comprises a layer having two n-type semiconductor regions which constitute an emitter region and a collector region, and which sandwich a lightly doped p-type base region. In operating conditions the base region is completely depleted leading to punchthrough, and generation of high optical conversion gain when the phototransistor is illuminated. The base region and part of the emitter and collector regions are covered with an oxide layer. The phototransistor can be fabricated by CMOS processing technology, so very large scale integrated circuits can be fabricated comprising a large number of the phototransistors.