Numerical Device Simulation Aided Study of RF-Stress-Caused Degradation in SiGe HBTs

TCAD simulations of an advanced SiGe HBT are performed with and without considering the impact of compressive lattice strain on the effective density of states and on the carrier mobility. Relaxation of compressive lattice strain is discussed as a possible physical cause of the collector current degradation in SiGe HBTs that has been experimentally observed in previously reported RF stress tests.