High Current Gain Silicon Carbide Bipolar Power Transistors

Silicon carbide NPN bipolar junction transistors were fabricated and a current gain exceeding 60 was obtained for a BJT with a breakdown voltage B
CEO
=1100 V. A reduction Of the current gain was observed after contact annealing at 950 °C and this was attributed to degradation of the oxide passivation. Device simulations with varying emitter doping resulted in a maximum current gain for an emitter doping around 1·10
¹⁹
cm
^-3
. Resistive turn-off measurements were performed and a minimum collector-emitter voltage (V
C
E) rise-time of 40 ns was found. The V
CE
rise-time showed a clear dependence on the on-state base current thus indicating a significant stored charge.