Abstract
In this paper, we summarize recent progresses in 4H-SiC BJTs at Purdue University. For 50 μm collector devices, BV <sub>CEO</sub> > 3,200V is achieved. Large devices (active area = 1.05 mm <sup>2</sup> ) exhibit common emitter current gain β around 15, and specific on-resistance R <sub>ON,SP</sub> of 78 mΩ-cm <sup>2</sup> . Smaller devices (active are = 0.0072mm <sup>2</sup> ) have ββ of 20 and R <sub>ON,SP</sub> of 28 mΩ-cm <sup>2</sup> . For 20 μm collector devices, β's greater than 50 and R <sub>ON,SP</sub> around 26 mΩ-cm <sup>2</sup> 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</sub> and negative coefficient of β show that 4H-SiC BJTs can be safely operated in parallel connections. We also observe that β 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.