A novel structure phototransistor CE-PTHPT

A phototransistor of CE-PTHPT (punch-through heterojunction phototransistor with control electrode) with novel emitter control electrode and wide band gap emitter has been designed. The devices were working under the depletion on the base region. The base current is nearly zero and the output noise current decreases eventually so as to increase the optical gain greatly. There is an i type layer between the emitter and base region, low doped base region, implant isolated planar device and decreased emitter area in this device. The novel CE-PTHPT has been fabricated in this paper. The optical gain of GaAlAs/GaAs CE-PTHPT for the incident light power 1.3 and 43 nW with the wavelength of 0.8 μm reached 1260 and 8108. The input noise current calculated is 3.7×10^-16 A/H_Z¹2/. For polysilicon emitter CE-PTHPT, the optical gain is 3083 at the input power of 0.174 μW. The optical gain of InGaAs/InP CE-PTHPT reaches 350 for an incident power of 0.3 μW at the wavelength of 1.55 μm.