Exploratory Development of SiC Bipolar Transistors and GaN Heterojunction Bipolar Transistors for High-Power Switching Applications
Final technical rept. 1 Jul 1999-30 Jun 2002
PURDUE UNIV LAFAYETTE IN SCHOOL OF ELECTRICAL AND COMPUTER ENGINERING
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Homojunction bipolar transistors BJTs have been designed, fabricated, and characterized in 4H-SiC Devices optimized for high current gain have betas as high as 55, a new record for SiC BJTs. Devices optimized for blocking voltage exhibit blocking voltages of 3,200 V, again a new record for SiC BJTs. For the high-gain devices, the critical parameter is the base doping, which must be high enough to prevent punchthrough, while low enough to achieve a high emitter injection efficiency. The optimum value in these devices is a doping of about 1xl017 cm3 at a base thickness of 1 micron. Another critical parameter is the lateral spacing between the edge of the emitter and the implanted P region used to form the base contact.
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