Differences in ac-analysis of Si/Si/sub 1-x/Ge/sub x/ HBTs using drift-diffusion and hydrodynamic based device simulators

This paper reports the differences in 2D device-level simulation based on drift-diffusion-ac and hydrodynamic-ac analysis of SiGe-HBTs. Different Ge profiles were simulated to determine the influence of nonstationary transport effects on device performance. A comparison between the two models is useful in order to estimate the differences of both models in device structure optimizing processes.