Interfacial Trap Effect on the DC and RF Characteristics of SiGe Heterojunction Bipolar Transistor

Abstract

In this paper, the effects of interfacial traps on the AC and RF characteristics of SiGe heterojunction bipolar transistor have been investigated. TCAD simulations were carried out by defining and varying traps near the emitter base spacer oxide which can replicate the effects of hot carriers under various stress conditions. Reduction in DC current gain is observed with increase in traps whereas AC current gain degradation is occurred only at low frequencies. It is found that the cut off frequency fT is insignificantly affected by traps. However, degradation in maximum oscillation frequency, fmax with trap density variations is significantly high. The S parameter simulations carried out for different trap densities shows significant variations in S11 and S21 parameters.