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Thermal analysis of a heterojunction bipolar transistor

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Date Issued:
1994
Summary:
The Heterojunction Bipolar Transistor (HBT) is capable of delivering high current density at microwave frequencies and are now being implemented in microwave circuitry as high power amplifiers. The heat generated during device operation is dissipated through the Gallium Arsenide substrate. Because of its poor thermal conductivity the junction temperature rise can be large enough to degrade and thermally limit the performance of the device. The power HBT with multiple emitter fingers are susceptible to the thermal effect due to non-uniform temperature distribution. This results in a thermal effect called thermal runaway causing thermal-induced current instability and hot spot formation thus destroying the device. Thermal shunt technique which has been developed to suppress this non-uniform temperature involves fabrication of a thick metal thermal shunt connecting all the fingers thus forming a strong thermal coupling between the emitter fingers. In this thesis 2 and 3-dimensional thermal simulations were carried out using Finite Element techniques to study the thermal behavior of the HBT's as a function of thermal shunt and other device design configurations such as the number of emitter fingers, thickness of thermal shunt, emitter spacing, Silicon as a substrate material, power variation etc. The results are projected as a design guideline for HBT device.
Title: Thermal analysis of a heterojunction bipolar transistor.
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Name(s): Kokkalera, Subbaiya U.
Florida Atlantic University, Degree grantor
Tsai, Chi-Tay, Thesis advisor
College of Engineering and Computer Science
Department of Ocean and Mechanical Engineering
Type of Resource: text
Genre: Electronic Thesis Or Dissertation
Issuance: monographic
Date Issued: 1994
Publisher: Florida Atlantic University
Place of Publication: Boca Raton, Fla.
Physical Form: application/pdf
Extent: 125 p.
Language(s): English
Summary: The Heterojunction Bipolar Transistor (HBT) is capable of delivering high current density at microwave frequencies and are now being implemented in microwave circuitry as high power amplifiers. The heat generated during device operation is dissipated through the Gallium Arsenide substrate. Because of its poor thermal conductivity the junction temperature rise can be large enough to degrade and thermally limit the performance of the device. The power HBT with multiple emitter fingers are susceptible to the thermal effect due to non-uniform temperature distribution. This results in a thermal effect called thermal runaway causing thermal-induced current instability and hot spot formation thus destroying the device. Thermal shunt technique which has been developed to suppress this non-uniform temperature involves fabrication of a thick metal thermal shunt connecting all the fingers thus forming a strong thermal coupling between the emitter fingers. In this thesis 2 and 3-dimensional thermal simulations were carried out using Finite Element techniques to study the thermal behavior of the HBT's as a function of thermal shunt and other device design configurations such as the number of emitter fingers, thickness of thermal shunt, emitter spacing, Silicon as a substrate material, power variation etc. The results are projected as a design guideline for HBT device.
Identifier: 15081 (digitool), FADT15081 (IID), fau:11859 (fedora)
Collection: FAU Electronic Theses and Dissertations Collection
Note(s): College of Engineering and Computer Science
Thesis (M.S.E.)--Florida Atlantic University, 1994.
Subject(s): Junction transistors
Thermal analysis
Microwave circuits
Held by: Florida Atlantic University Libraries
Persistent Link to This Record: http://purl.flvc.org/fcla/dt/15081
Sublocation: Digital Library
Use and Reproduction: Copyright © is held by the author, with permission granted to Florida Atlantic University to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Use and Reproduction: http://rightsstatements.org/vocab/InC/1.0/
Host Institution: FAU
Is Part of Series: Florida Atlantic University Digital Library Collections.