Diffusion-Induced Degradation of AlGaAs/GaAs Heterojunction Bipolar Transistors by Thermal Stress

Two-dimensional simulations of the impact of beryllium diffusion at the junction interface of AlGaAs/GaAs heterojunction bipolar transistors (HBTs) on the device performance are reported. It is shown that the current driving capability is greatly influenced by the redistributed profile of beryllium at the emitter-base junction due to outdiffusion. In addition, the dependence of the RP characteristics on the Be outdiffusion is estimated for a series of AlGaAs/GaAs HBTs with different Be distribution.