1200-V 5.2-mΩ · cm² 4H-SiC BJTs with a high common-emitter current gain

This letter presents fabrication of a power 4H-SiC bipolar junction transistor (BJT) with a high open-base breakdown voltage BV_CEO ≈ 1200 V, a low specific ON-resistance RSP_ON ≈ 5.2 mΩ · cm², and a high common-emitter current gain β ≈ 60. The high gain of the BJT is attributed to reduced surface recombination that has been obtained using passivation by thermal silicon dioxide grown in nitrous oxide (N₂O) ambient. Reference BJTs with passivation by conventional dry thermal oxidation show a clearly lower current gain and a more pronounced emitter-size effect. BJTs with junction termination by a guard-ring-assisted junction-termination extension (JTE) show about 400 V higher breakdown voltage compared with BJTs with a conventional JTE.