Author Type

Graduate Student

Date of Award

1994

Document Type

Thesis

Publication Status

Version of Record

Submission Date

October 2026

Thesis/Dissertation Advisor [Chair]

Tsai, Chi-Tay

Abstract

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.

Extent

125 p.

Comments

College of Engineering and Computer Science|FAU Electronic Theses and Dissertations Collection|Thesis (M.S.E.)--Florida Atlantic University, 1994.|College of Engineering and Computer Science

Identifier

FADT15081

Format

pdf

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