Avalanche breakdown of novel 650 V SiC Schottky-barrier rectifiers is investigated. The rectifier diode has low leakage current for the temperatures up to 300 degrees C. Thermal coefficient of avalanche breakdown increases with the temperature to around 0.009%/K at 200 degrees C. Near-uniform avalanche breakdown is verified using emission imaging, and maximum specific avalanche energy of 20.7 J/cm(2) is achieved. The critical temperature for stability in unclamped inductive switching (UIS) is above 520 degrees C as estimated through thermal simulation. Longterm walkout of breakdown voltage at 176 degrees C is less than 0.02%.