Current gain rolloff in graded-base SiGe heterojunction bipolar transistors

Author

Crabb, Emmanuel F. ; Cressler, John D. ; Patton, Gary L. ; Stork, Johannes M C ; Comfort, James H. ; Sun, Jack Y C

Author_Institution

IBM Thomas J. Watson Res. Center, Yorktown Heights, NY, USA

Volume

14

Issue

4

fYear

1993

fDate

4/1/1993 12:00:00 AM

Firstpage

193

Lastpage

195

Abstract

The authors report the experimental observation of a novel effect in SiGe heterojunction bipolar transistors (HBTs) with graded bases which results in a significant emitter-base bias dependence of the current gain. The nonideal collector current is caused by the interaction of the bias dependence of the emitter-base space-charge region width and the exponential dependence of the collector current on the germanium concentration at the edge of the space-charge region. The resulting current gain rolloff must be taken into account for accurate modeling of bipolar transistors with bandgap grading in the base.<>

Keywords

Ge-Si alloys; heterojunction bipolar transistors; semiconductor materials; space charge; SiGe; bandgap grading; bias dependence; current gain rolloff; emitter-base bias dependence; emitter-base space-charge region width; graded base HBT; heterojunction bipolar transistors; modeling; nonideal collector current; Associate members; Current density; Degradation; Electron devices; Germanium silicon alloys; Heterojunction bipolar transistors; Lifting equipment; Photonic band gap; Silicon germanium; Temperature dependence;

fLanguage

English

Journal_Title

Electron Device Letters, IEEE

Publisher

ieee

ISSN

0741-3106

Type

jour

DOI

10.1109/55.215153

Filename

215153