Spectra study of He-irradiation induced defects in 6H-SiC

Abstract

Specimens of 6H-SiC were irradiated by 300keV He ions at temperatures of RT, 450, 600 and 750 ℃ with fluences ranging from 11015 to 11017 cm-2. Post-irradiation, virgin and irradiated 6H-SiC specimens are measured and studied by microscopic laser confocal Raman spectrometer and UV-visible transmission apparatus. Analyses of both experimental results shown that production and recovery of defects caused by irradiation are directly related to the fluences and temperatures. Amorphization of 6H-SiC irradiated at RT occurrs, which is reflected by the disappearance of the Raman peaks and the saturation of the relative Raman intensity(simultaneously a strong Si-Si peak appears). Recovery of defects may exist in high-temperature irradiation, when helium bubbles do not exist, so that irradiation-induced defects can be easily recovered during irradiation process at elevated temperatures; but when helium bubbles are present, they can inhibit defects to recover, as shown in the trend of slopes of curves representing the relative Raman intensity and the relative absorption coefficients. This paper mainly focuses on the effects of helium bubbles on defect accumulation and recovery under the condition of high temperature irradiation, and then the comparison with the results of 6H-SiC irradiated by Si ions at elevated temperatures.