Comparison of silicon carbide and GaAs schottky diode

The critical properties of power devices are high reverse breakdown voltage and low forward ON state resistance, R_on, during high forward current density operation. Both of these parameters are very sensitive to temperature. Nowadays silicon carbide (SiC) and GaAs are two most important materials for power device applications. SiC has been widely accepted as being superior to GaAs because it has much higher electric breakdown field, saturated electron drift velocity and thermal conductivity. In this work, the electrical performance and reliability of SiC Schottky diodes (SD) are evaluated and compared to commercially available GaAs SDs. Accelerated life tests (ACT) and high temperature device characterization have been performed. The activation energy and mean time to failure (MTTF) were calculated. Our results show that the strong temperature dependence of R_on is consistent with phonon scattering theory. Based on Baliga's figure-of-merit (BFOM) model, our result shows that under higher operating temperatures (>260°C) the GaAs devices have lower R_on than SiC, thus, it may be preferable to use GaAs over SiC for high temperature power device applications.