Improvement of SiO2/SiC Interface Properties by Nitrogen Radical Irradiation
Effects of nitrogen (N) radical irradiation on SiO2/4H- and 6H-SiC interface properties were investigated. N radicals were irradiated to dry thermal oxides on SiC. X-ray photoelectron spectroscopy measurements revealed that N atoms were introduced into the SiO2/SiC interface with 1 at%. To evaluate the interface state density, high and low frequency capacitance - voltage characteristics were measured using n-type metal-oxide-semiconductor (MOS) structures. The interface state density was reduced by irradiation of N radicals. Thin oxides were found to be effective in reducing the interface state density. The channel mobility of n-channel inversion-mode MOS field-effect transistors was improved. The N atom incorporation gives a favorable effect for the improvement of SiO2/SiC interface properties.