Temperature Dependent Design of Silicon Carbide Schottky Diodes

A well designed Silicon Carbide (SiC) Schottky-Barrier Diode (SBD) has to optimize reverse leakage current in addition to the familiar silicon (Si) device trade-off of avalanche breakdown voltage (BV) and forward voltage drop (VF). Reverse leakage current is a strong function of temperature and we show experimentally that this sensitivity of reverse leakage to temperature is a function of the electric field at the Schottky interface at rated voltage. We model this phenomenon using Hatakeyama's approximations of electron emission across the metal-SiC barrier. This model and our results point to a previously un-reported design trade-off between BV margin over rated voltage and temperature dependence of SiC SBD rated reverse leakage current. Using this trade-off, we show that optimum epitaxial design of a SiC SBD is different for a given rated voltage than what mere BV vs R-on considerations indicate. Optimized epitaxy is also different for different JBS geometries.