Effect of uni-traveling-carrier on saturation current, optical responsivity and response speed of phototransistor

In this paper, the optical gain characteristics and optical high frequency characteristics of an InP-based uni-traveling-carrier double heterojunction phototransistor (UTC-DHPT) are illustrated. The detailed analysis of UTC effects on those perfomaces show that UTC transport mechanism successfully weaks the space charge effect in the collector junction and breaks the limitation of low mobility of the holes. Compared with traditional single heterojunction phototransistor (SHPT), UTC-DHPT improves its processing ability of high power optical signal and provides high saturation current, high responsivity and high response speed simultaneously.