Common-emitter current gain of Al/sub x/Ga/sub 1-x/As/GaAs/GaAs heterojunction bipolar transistors operating at small collector current

Although the effects of electrical stress and temperature on the performance of the InGaP/GaAs heterojunction bipolar transistors (HBTs) have been widely studied and reported, little or none was reported for the InGaP/GaAs heterojunction phototransistors (HPTs) in the literature. In this paper, we discuss the temperature-dependent characteristic of InGaP/GaAs HPTs before and after electrical stress and assess the effectiveness of the emitter-ledge passivation, which was found to effectively keep the InGaP/GaAs HBTs from degrading at higher temperature or after an electrical stress. The emitter-ledge passivation is also effective keeping a higher optical gain even at higher temperature. An electrical stress was given to the HPTs by keeping the collector current at 60 mA for 15 min. Since the collector current density as an electrical stress is 24 A/cm2 and much smaller than the stress usually given to smaller HBTs for the stress test, the decreased optical gain was not observed when it was given at room temperature. However, when it was given at 420 K, significant decreases of the current gain and optical gain were observed at any temperature. Nevertheless, the emitter-ledge passivation was found effective in minimizing the decreases of the current gain and optical gain.

Download Full-text

SiC Heterojunction Bipolar Transistors with AlN/GaN Short-Period Superlattice Widegap Emitter

Materials Science Forum ◽

10.4028/www.scientific.net/msf.645-648.1029 ◽

2010 ◽

Vol 645-648 ◽

pp. 1029-1032

Author(s):

Hiroki Miyake ◽

Tsunenobu Kimoto ◽

Jun Suda

Keyword(s):

Potential Barrier ◽

Heterojunction Bipolar Transistors ◽

Bipolar Transistors ◽

Current Gain ◽

Band Offset ◽

Algan Layer ◽

Emitter Current ◽

Al Content ◽

Short Period ◽

Successful Control

In this study, new SiC-based heterojunction bipolar transistors (HBT) are proposed. An n-type AlN/GaN short-period superlattice (quasi-AlGaN) layer is grown on a SiC pn junction as a widegap emitter. By using quasi-AlGaN emitter, we have demonstrated successful control of band offset of AlGaN/SiC. Quasi-AlGaN/SiC HBT with an Al content over 0.5, which has no potential barrier to electron injection from an n-AlGaN emitter to a p-SiC base, exhibited a common-emitter current gain of β ~ 2.7, whereas the HBT with an Al content below 0.5 showed β ~ 0.1.

Download Full-text

The collapse of current gain in multi-finger heterojunction bipolar transistors: its substrate temperature dependence, instability criteria, and modeling

IEEE Transactions on Electron Devices ◽

10.1109/16.324577 ◽

1994 ◽

Vol 41 (10) ◽

pp. 1698-1707 ◽

Cited By ~ 74

Author(s):

W. Liu ◽

A. Khatibzadeh

Keyword(s):

Substrate Temperature ◽

Temperature Dependence ◽

Heterojunction Bipolar Transistors ◽

Bipolar Transistors ◽

Current Gain ◽

Instability Criteria

Download Full-text

Current gain-Early voltage products in heterojunction bipolar transistors with nonuniform base bandgaps

IEEE Electron Device Letters ◽

10.1109/55.116947 ◽

1991 ◽

Vol 12 (12) ◽

pp. 661-663 ◽

Cited By ~ 41

Author(s):

E.J. Prinz ◽

J.C. Sturm

Keyword(s):

Heterojunction Bipolar Transistors ◽

Bipolar Transistors ◽

Current Gain

Download Full-text

Current Gain of 4H-SiC Bipolar Transistors Including the Effect of Interface States

Materials Science Forum ◽

10.4028/www.scientific.net/msf.483-485.889 ◽

2005 ◽

Vol 483-485 ◽

pp. 889-892 ◽

Cited By ~ 6

Author(s):

Martin Domeij ◽

Erik Danielsson ◽

Hyung Seok Lee ◽

Carl Mikael Zetterling ◽

Mikael Östling

Keyword(s):

Side Wall ◽

Interface States ◽

Bipolar Transistors ◽

Current Gain ◽

Poor Agreement ◽

Collector Current ◽

Bandgap Narrowing ◽

Pulsed Measurements ◽

Emitter Junction ◽

Constant Distribution

The current gain (b) of 4H-SiC BJTs as function of collector current (IC) has been investigated by DC and pulsed measurements and by device simulations. A measured monotonic increase of b with IC agrees well with simulations using a constant distribution of interface states at the 4H-SiC/SiO2 interface along the etched side-wall of the base-emitter junction. Simulations using only bulk recombination, on the other hand, are in poor agreement with the measurements. The interface states degrade the simulated current gain by combined effects of localized recombination and trapped charge that influence the surface potential. Additionally, bandgap narrowing has a significant impact by reducing the peak current gain by about 50 % in simulations.

Download Full-text

Current gain increase in AlGaAs/GaAs heterojunction bipolar transistors using AlGaAs layer overgrowth

Applied Physics Letters ◽

10.1063/1.112065 ◽

1994 ◽

Vol 65 (11) ◽

pp. 1403-1405 ◽

Cited By ~ 3

Author(s):

S. R. D. Kalingamudali ◽

A. C. Wismayer ◽

R. C. Woods ◽

J. S. Roberts

Keyword(s):

Heterojunction Bipolar Transistors ◽

Bipolar Transistors ◽

Current Gain ◽

Algaas Layer

Download Full-text

Prevention of InP/InGaAs/InP Double Heterojunction Bipolar Transistors from Current Gain Reduction during Passivation

MRS Proceedings ◽

10.1557/proc-833-g3.7 ◽

2004 ◽

Vol 833 ◽

Author(s):

Byoung-Gue Min ◽

Jong-Min Lee ◽

Seong-Il Kim ◽

Chul-Won Ju ◽

Kyung-Ho Lee

Keyword(s):

Heterojunction Bipolar Transistors ◽

Silicon Oxide ◽

Surface Recombination ◽

Surface States ◽

Bipolar Transistors ◽

Base Layer ◽

Current Gain ◽

Device Structure ◽

Double Heterojunction ◽

Gain Reduction

ABSTRACTA significant degradation of current gain of InP/InGaAs/InP double heterojunction bipolar transistors was observed after passivation. The amount of degradation depended on the degree of surface exposure of the p-type InGaAs base layer according to the epi-structure and device structure. The deposition conditions such as deposition temperature, kinds of materials (silicon oxide, silicon nitride and aluminum oxide) and film thickness were not major variables to affect the device performance. The gain reduction was prevented by the BOE treatment before the passivation. A possible explanation of this behavior is that unstable non-stoichiometric surface states produced by excess In, Ga, or As after mesa etching are eliminated by BOE treatment and reduce the surface recombination sites.

Download Full-text