High-performance power BJTs in 4H-SiC

In this paper, we summarize recent progress in 4H-SiC BJTs at Purdue University. For 50 /spl mu/m collector devices, BV/sub CEO/>3,200 V is achieved. Large devices (active area=1.05 mm/sup 2/) exhibit common emitter current gain /spl beta/ of around 15, and. specific on-resistance R/sub ON,SP/ of 78 m/spl Omega//cm/sup 2/. Smaller devices (active area=0.0072 mm/sup 2/) have /spl beta/ of 20 and R/sub ON,SP/ of 28 m/spl Omega//cm/sup 2/. For 20 /spl mu/m collector devices, /spl beta/s greater than 50 and R/sub ON,SP/ around 26 m/spl Omega//cm/sup 2/ are observed. The blocking voltage is low (500-700 V) for these devices because of aluminum spiking during the base contact anneal. The observed positive temperature coefficient of R/sub ON,SP/ and negative coefficient of /spl beta/ show that 4H-SiC BJTs can be safely operated in parallel connection. We also observe that /spl beta/ decreases as the spacing between base contact implant and emitter finger is reduced. We attribute this to recombination at defect sites in the p+ implanted base contact.