Effect of Ge Profiles on the Performance of Lateral SiGe Heterojunction Bipolar Transistors with Substrate Bias

In the paper, the effect of Ge profiles on the performance of lateral SiGe heterojunction bipolar transistor (LHBT) on silicon-on-insulator (SOT) substrate with positive bias voltage has been studied. With the aid of substrate bias (V-S), the peak current gain (beta) of LHBT with trapezoidal Ge profile is obviously enhanced, which is almost as same as LHBT with uniform Ge profile. At the same time, the beta of LHBT with trapezoidal Ge profile is kept as temperature increases. However, the beta of LHBT with uniform Ge profile is decreased as temperature increases. Furthermore, for LHBT with trapezoidal Ge profile, the peak junction temperature is lowered by 20.51K and the cut-off frequency (f(T)) is also improved by 158.4 GHz when compared with that of the uniform one. The results show that LHBTs with trapezoidal Ge profile could achieve the superior electrical, thermal, and high frequency performance at the same time, which provides useful guidelines to design SiGe HBTs for microwave and digital or mixed-signal applications.