Bias-temperature stress experiments performed on two generations of SiC power MOSFETs from the same manufacturer show reductions in threshold voltage (V_T) shift at elevated temperatures from first- to second-generation. The negative V_T shift is reduced from a range of-1 V to -1.6 V to a range of-100 mV to -300 mV for temperatures from 125°C to 175°C. Plastic-packaged parts show a gate-bias-independent junction leakage current at temperatures above the rated temperature, suggesting that the plastic packaging introduces an extrinsic leakage path. Junction leakage in metal-packaged parts can be significantly reduced by applying a small negative gate bias at elevated temperatures. Switching gate bias temperature stresses show V_T shifts dependent on duty cycle, with a higher duty cycle resulting in a higher rate of V_T shift. Cumulative damage effects may be observed between switching gate bias stresses.
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