Analytical Modeling of a Novel Heterojunction Bipolar Transistor Structure

A novel heterojunction bipolar transistor (HBT) structure is presented in this paper. Emitter region of this transistor is made of n type Si-Ge while base and collector regions are made of p and n type Ge respectively. Current gain (beta) and forward transit time(tauF) are two important factors for determining the performance of a transistor. Variations of current gain and forward transit time with temperature and other device parameters are predicted with the help of analytical models. Studies have been made for different Ge composition in the emitter and doping concentration in the base region. Performance characteristics of this novel device are compared with those of Si BJT and Si-SiGe HBTs.