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Active and Passive Electronic Components
Volume 24 (2001), Issue 4, Pages 265-287

Thermal Effect and Frequency Response Analyses on Heterojunction Bipolar Power Transistor

1Optoelectronic Semiconductor Center, Department of Electrical Engineering, Far East College, Hsin-Shih, Taiwan 744, Tainan, China
2lnstitute of Microelectronics, Department of Electrical Engineering, National Cheng-Kung University, Taiwan 701, Tainan, China
3P.O. BOX 345, Taiwan 704, Tainan, China

Received 25 June 2001; Accepted 20 August 2001

Copyright © 2001 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Heterojunction bipolar transistors (HBT) based on Npn AlGaAs/GaAs material system have attracted considerable attention for microwave power and digital applications due to their high speed and high current capabilities. In this paper, a numerical model based on the Npn AlGaAs/GaAs HBT structure for the carrier transport is presented. Three figures of merit on device operation, current gain, cut-off frequency and maximum oscillation frequency are calculated. Besides, thermal instability plays an important role on power HBT resulted from the low thermal conductivity in GaAs. The generated heat will increase the junction temperature and cause self-destruction. Therefore, the thermal runaway study of the junction temperature, current–voltage (IV) characteristics and frequency response using an analytical thermal model is described.