Silicon carbide Schottky diodes and MOSFETs: Solutions to performance problems

Silicon carbide has long been hailed as the successor to silicon in many power electronics applications. Its superior electrical and thermal properties have delivered devices that operate at higher voltages, higher temperatures and with lower on-resistances than silicon devices. However, SiC Schottky diodes are still the only devices commercially available today. Though SiC Schottkys are now being used with silicon IGBTs in dasiahybridpsila inverter modules, the real advantages will be seen when silicon switching devices can be replaced by SiC. This paper describes the current state of SiC diode and MOSFET technology, discussing possible solutions to making these devices commercially viable.

I. Introduction

Developments in silicon carbide growth technology have led to the release of 100 mm diameter wafers with zero micropipes (ZMP®) and significant reductions in the densities of a number of other defects and dislocations. In addition to the progress in crystal quality and wafer diameter, made by Cree [1], technology for increasing growth rates [2] using chlorine gas chemistry should also contribute to lower wafer prices. Currently, cost is still high but there are signs from manufacturing giants such as Toyota that the improved performance of SiC over silicon devices could eventually make SiC a financially viable product [3]. Despite these encouraging noises, commercially available SiC devices have been restricted to Schottky diodes, from Cree, Infineon and more recently Bipolar Junction Transistor for power applications from the new Swedish manufacturer, TRANSIC [4].