Stability of Electrical Characteristics of SiC “Super” Junction Transistors under Long-Term DC and Pulsed Operation at various Temperatures

Abstract

The reliability of the electrical characteristics of SiC "Super" Junction Transistors (SJTs) is investigated under long-term avalanche-mode, DC and pulsed-current operation. There is absolutely no change in the blocking I-V characteristics after a 934 hour repetitive avalanche stress test. Long-term operation of the Gate-Source diode (open-Drain mode) alone does not result in any degradation of the on-state voltage drop (V F ) or current gain (β). Long-term operation in common-Source mode results in negligible V F or β degradation, if the base-plate is maintained at 25 °C. A greater degradation of β results with increasing base-plate temperature. The same total electrical charge, if passed through the SJT as a pulsed current instead of a DC current results in a smaller β reduction. It is also shown that this β degradation can be reversed by annealing at ≥ 200 °C, suggesting the possibility of degradation-free operation of SiC SJTs, when operating in pulsed current mode at ≥ 200 °C temperatures.