Characterization of Interface State Density of SiO_2/SiC(000-1) Based on Oxygen Concentration at the Interface during Thermal Oxidation

摘要

The interface state density for SiO_2/4H-SiC(000-1) was investigated and characterized with oxygen concentration at the interface during oxidation. The oxidation concentration was calculated by fitting the experimental oxidation data with the Deal-Grove model. It was found that the deep level (1.0 eV below the bottom of the conduction band of 4H-SiC) of the interface state was correlated to the concentration of oxygen at the interface. The interface state density decreases as the oxygen concentration increases, which corresponds to better interface property for thinner SiO_2 film. It was concluded that oxygen molecules act as remover of C-related impurities from the SiO_2 film. High temperature oxidation is effective to reduce interface state density, which is probably due to increase in the formation energy of CO giving rise to enhancement of out diffusion of the impurities.