Impact of Interface Defect Passivation on Conduction Band Offset at SiO<sub>2</sub>/4H-SiC Interface

Abstract

The change in energy band alignment of thermally grown SiO2/4H-SiC(0001) structures due to an interface defect passivation treatment was investigated by means of synchrotron radiation photoelectron spectroscopy (SR-PES) and electrical characterization. Although both negative fixed charge and interface state density in SiO2/SiC structures were effectively reduced by high-temparature hydrogen gas annealing (FGA), the conduction band offset (ΔEc) at the SiO2/SiC interface was found to be decreased by about 0.1 eV after FGA. In addition, a subsequent vacuum annealing to induce hydrogen desorption from the interface resulted in not only a slight degradation in interface property but also a partial recovery of ΔEc value. These results indicate that the hydrogen passivation of negatively charged defects near the thermally grown SiO2/SiC interface causes the reduction in conduction band offset. Therefore, the tradeoff between interface quality and conduction band offset for thermally grown SiO2/SiC MOS structure needs to be considered for developing SiC MOS devices.