DEGRADATION MECHANISMS AND CHARACTERIZATION TECHNIQUES IN SILICON CARBIDE MOSFETs AT HIGH-TEMPERATURE OPERATION

Due to a number of advantages over silicon, including higher breakdown field, higher operational junction temperature, and higher thermal conductivity, silicon carbide (SiC) has generated keen interest as a material of choice for power electronic devices. Device characteristics resulting directly from SiC’s superior material properties, including enhanced ability to withstand high voltage, lower on-state resistance and capacitance permitting higher switching frequency, and reduced thermal management requirements, give SiC-based power devices the potential to greatly reduce the system footprint and cost, and to increase system efficiency. Among all the possible semiconductor switches, the field-effect transistor provides very low switching loss and is thus an attractive option, especially at high switching frequency. A SiC metal-oxide semiconductor field-effect transistor (MOSFET) is now commercially available that provides a blocking voltage of 1200 volts (V), maximum DC current capability of 33 amps (A), and on-state resistance Ron of 80 milliohms (mΩ). However, the reliability of the silicon oxide (SiO2) insulator on SiC at high temperature is an open question. The predominant degradation trends in this MOSFET under hightemperature overvoltage and pulsed overcurrent stress are reported in this work. We also describe the development of a microcontroller-based condition monitoring module that can track changes in the semiconductor device characteristics in order to improve real-world system availability.