Crystallization and surface erosion of SiC by ion irradiation at elevated temperatures

Abstract

The effects of high dose ion irradiation through amorphous surface layers on single crystalline 6H–SiC at elevated temperatures are studied in detail. Material swelling, subsequent densification, and surface erosion are quantified for irradiation at 500 °C. Ion beam induced recrystallization is investigated in the temperature range between 300 and 1300 °C. The results demonstrate that undisturbed epitaxial regrowth of an amorphous surface layer in (0001)-oriented 6H–SiC cannot be achieved by ion irradiation. The shift of the amorphous/crystalline interface observed by Rutherford backscattering spectrometry/channeling analysis is a consequence of columnar growth and surface erosion. The columnar growth starts inside the heavily damaged transition region between the amorphous surface layer and the single crystalline bulk material. It is stopped by random nucleation which is strongly enhanced by ion irradiation in the temperature range between 300 and 1000 °C. Neither the interface roughness nor the kind of impurity atoms influence the thickness of the columnar layer. At higher temperatures, the interface shift is dominated by thermal regrowth and ion beam enhanced surface erosion.