DocumentCode :
1311804
Title :
Neutral base recombination and its influence on the temperature dependence of Early voltage and current gain-Early voltage product in UHV/CVD SiGe heterojunction bipolar transistors
Author :
Joseph, Alvin J. ; Cressler, John D. ; Richey, David M. ; Jaeger, Richard C. ; Harame, David L.
Author_Institution :
Alabama Microelectron. Sci. & Technol. Center, Auburn Univ., AL, USA
Volume :
44
Issue :
3
fYear :
1997
fDate :
3/1/1997 12:00:00 AM
Firstpage :
404
Lastpage :
413
Abstract :
We present the first comprehensive investigation of neutral base recombination (NBR) in ultra-high vacuum/chemical vapor deposited (UHV/CVD) SiGe heterojunction bipolar transistors (HBT´s), and its influence on the temperature characteristics of Early voltage (VA ) and current gain-Early voltage product (βVA). We show that a direct consequence of NBR in SiGe HBT´s is the degradation of VA when transistors are operated with constant-current input (forced-IB) as opposed to a constant-voltage input (forced-VBE). In addition, experimental and theoretical evidence indicates that with cooling, VA in SiGe HBT´s degrades faster than in Si bipolar junction transistors (BJT´s) for forced-IB mode of operation. Under the forced-VBE mode of operation, however, SiGe HBT´s exhibit a thermally-activated behavior for both VA and βVA, in agreement with the first-order theory. The differences in VA as a function of the input bias and temperature for SiGe HBT´s are accurately modeled using a modified version of SPICE. The performance of various practical SiGe HBT circuits as a function of temperature, in the presence of NBR, is analyzed using this calibrated SPICE model
Keywords :
Ge-Si alloys; SPICE; bipolar integrated circuits; electron-hole recombination; heterojunction bipolar transistors; semiconductor device models; semiconductor materials; Early voltage; Gummel characteristics; SiGe; SiGe HBT; SiGe HBT circuits; UHV/CVD SiGe heterojunction bipolar transistors; calibrated SPICE model; constant-current input; constant-voltage input; current gain-Early voltage product; first-order theory; input bias dependence; neutral base recombination; temperature dependence; thermally-activated behavior; Chemical products; Chemical vapor deposition; Cooling; Degradation; Germanium silicon alloys; Heterojunction bipolar transistors; SPICE; Silicon germanium; Temperature; Voltage;
fLanguage :
English
Journal_Title :
Electron Devices, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9383
Type :
jour
DOI :
10.1109/16.556150
Filename :
556150
Link To Document :
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