An Analytical Model of SiGe Heterojunction Bipolar Transistors on SOI Substrate for Large Current Situations

The large current effect of silicon germanium heterojunction bipolar transistors fabricated on thin silicon-on-insulator is included in the model. As the current is two-dimensional, the injection for large current is vertical plus horizontal and is quite different from that of the bulk device. Critical parameters modeling the large current, such as the collector injection width, the hole density and the corresponding potential in the injection region, are discussed, and the influence to the transit time is also analyzed.