Analytical modelling of base transit time of SiGe HBTS including effect of temperature

Si/SiGe heterojunction bipolar transistors have increasingly become important in high speed applications due to better performance of these devices with a modest increase in process complexity. Base transit time is an important factor to determine the speed of these devices. An analytical model is developed here to predict the variation of base transit time with temperature and other device parameters. Studies have been made for both uniform and exponential doping distributions with different Ge profiles in the base region.