Aluminum nitride for 6H-SiC power devices

Abstract

Aluminum nitride (AlN) is a potential gate insulator material for 6H-SiC metal-insulator-semiconductor (MIS) devices for high temperature and high power applications. A critical requirement for a viable gate insulator material is that the insulator/semiconductor interface must have a very low interface state density, low insulator fixed charge density, as well as a low density of interfacial trapping centers. Our capacitance-voltage (CV) measurements have shown that it is possible to obtain an AlN/6H-SiC interface with such characteristics. Although CV measurements done at 573 K have shown evidence of the activation of deeper interfacial charged centers, they still reveal the presence of a low number of interface states and low insulator charge density. The disadvantage of this material system is the high leakage current density. However, by using a stacked AlN structure, we have found that it is possible to obtain MIS structures that are able to sustain breakdown fields close to the theoretical values. The possible use of a very thin AlN layer to enhance the characteristics of a Au-6H-SiC Schottky diode will also be discussed.