Sodium, Rubidium and Cesium in the Gate Oxides of SiC MOSFETs

Abstract

Large group-I elements such as sodium, rubidium and cesium have recently been incorporated in the gate oxide of SiC power MOSFETs. In the case of sodium incorporation, enhanced field effect mobilities have been definitively observed. Based on density functional calculations, we find large group-I elements serve as a shallow impurities near the interface. The enhanced mobility, observed in the case of sodium, can be explained in terms of an impurity band model.