Novel Approach for Improving Interface Quality of 4H-SiC MOS Devices with UV Irradiation and Subsequent Thermal Annealing

Abstract

We report on the harmful impact of ultraviolet (UV) light irradiation on thermally grown SiO2/4H-SiC(0001) structures and its use in subsequent thermal annealing for improving electrical properties of SiC-MOS devices. As we previously reported [1], significant UV-induced damage, such as positive flatband voltage shift and hysteresis in capacitance-voltage curves as well as increased interface state density, was observed for SiC-MOS devices with thermally grown oxides. Interestingly, the subsequent annealing of damaged SiO2/SiC samples resulted in superior electrical properties to those for untreated (fresh) devices. These findings imply that UV irradiation of the SiO2/SiC structure is effective for eliciting pre-existing carbon-related defects and transforming them into a simple configuration that can be easily passivated by thermal treatment.