Design of dual use, high efficiency, 4H-SiC Schottky and MPS diodes

Abstract

The prime benefit of the SiC Schottky diode lies in its ability to switch fast (<50 ns) and with almost no reverse recovery charge. The incorporation of a SiC Schottky-type rectifier in typical power-electronic systems, such as motor drive circuits and switching power supplies, will virtually eliminate the switching losses. In the forward bias, Ti Schottky diode provides a forward current density of 100 A/cm/sup 2/ at a forward drop of 1.15 V, at room temperature. However, the low barrier height of Ti Schottky diode results in a very high room temperature leakage current density of 300 /spl mu/A/cm2 at 500 V. Furthermore, the leakage current becomes unacceptable at temperatures higher than 100/spl deg/C. A 4H-SiC merged PiN Schottky (MPS) diode uses interdigitated p/sup +/ regions between Schottky contacts to limit the electric field at the Schottky interface during the off-state operation of the device. It has a low on-state voltage drop and fast switching of a Schottky diode and offers a low off-state leakage current like the PiN diode. The on-state and off-state performance was optimized by analyzing the effect of adjacent p/sup +/ region width and spacing by 2D device simulations.