Hot Carrier Effects on HighFrequency Characteristics of SiGe HBTs

Abstract

ABSTRACTHot carrier (HC)induced degradation effects on the high-frequency characteristics of SiGe Heterojunction Bipolar Transistors (HBTs) are investigated using the TCAD tool. Simulations are carried out on a 2D structure with specific trap definitions to analyse the high-frequency figures of merit. The DC and low-frequency AC gains show similar degradation due to the generation of nonideal base current. No significant variation is observed in cut-off frequency mainly due to the minimal effect of HCs on transconductance and base emitter capacitance. However, significant degradation in maximum oscillation frequency is observed primarily because of the rise in base resistance. Finally, S parameter simulations are also carried out to investigate the hot carrier effect on RF characteristics and found that the parameters S11 and S21 are affected by HCs.KEYWORDS: SiGe HBThot carrier degradationhigh-frequency characteristicsS parameters AcknowledgmentsThe authors would like to acknowledge the DST, the Government of India, for providing improved infrastructure to the host institution through the FIST project. The authors also extend their sincere thanks to the MEMS and Microelectronics Laboratory, IIT Madras, for rendering the lab facility to do the simulations. The authors sincerely thank Dr Anjan Chakravorty, IIT Madras, and Dr Uppili S. Raghunathan, GlobalFoundries, USA, for useful preliminary discussions.Disclosure statementNo potential conflict of interest was reported by the author(s).