An implanted-emitter 4H-SiC bipolar transistor with high current gain

SiC has long been recognized as the material of choice for high voltage, high temperature, high power applications. Bipolar transistors are attractive due to their small forward voltage drop and ease of fabrication compared to MOSFETs. A previously fabricated epi-emitter BJT by Cree Research showed a common emitter current gain of 12 in 6H-SiC (Wang et al., 1995). The implanted-emitter BJT is more flexible in the control of the emitter depth and doping concentration compared to the epi-emitter BJT. In this work, we report an epi-base, implanted-emitter, npn bipolar transistor on 4H-SiC which shows a maximum common emitter current gain (/spl beta/) of 36; the highest current gain reported for any polytype of SiC. The forward drop is /spl sim/1 V at a forward current density of 50 A/cm/sup 2/.