Title :
Base transit time for SiGe-base heterojunction bipolar transistors
Author :
Gao, G.-B. ; Morkoc, H.
Author_Institution :
Coordinated Sci. Lab., Illinois Univ., Urbana, IL, USA
Abstract :
The base transit time expressions for SiGe base heterojunction bipolar transistors are presented including the accelerating field effects due to the base bandgap grading and doping grading, and the retarding field (opposing drift field) effect from the graded boron profile down towards the emitter. It is found that the retarding field exhibits 40-80% contribution to the base transit time, depending on the boron concentration near the emitter. The results of base transit time from these analytic expressions are unambiguously supported by the published simulation data.
Keywords :
Ge-Si alloys; boron; heterojunction bipolar transistors; semiconductor device models; semiconductor doping; SiGe base; SiGe:B; accelerating field effects; base bandgap grading; base transit time; base transit time expressions; doping grading; graded B profile; heterojunction bipolar transistors; opposing drift field; retarding field;
Journal_Title :
Electronics Letters
DOI :
10.1049/el:19910884
