Decrease in interface states density of 4H-SiC MOS under high electric field stress

An Al/SiO/sub 2//4H-SiC metal-insulator-semiconductor (MOS) structure has been characterized using high frequency C-V measurements. By subjecting the MOS to high electric field stress (6 MV/cm), the flat-band voltage and effective oxide charge have been found to increase with stress time. In contrast, there is a decrease in the interface states density upon the electric field stress. The results can be explained by electron trapping in the complicated intermediary interfacial layer between SiO/sub 2/ and 4H-SiC.