Disordering behavior and helium diffusion in He+ irradiated 6H–SiC

Abstract

Single-crystal 6H–SiC wafers were irradiated at 300 K with 50 keV He+ ions to fluences ranging from 7.5 to 250 He+/nm2. Ion-channeling experiments with 2.0 MeV He+ Rutherford backscattering spectrometry were performed to determine the depth profile of Si disorder. The measured profiles are consistent with SRIM-97 simulations at and below 45 He+/nm2 but higher than the SRIM-97 prediction at both 100 and 150 He+/nm2. Cross-sectional transmission electron microscopy study indicated that the volume expansion of the material is not significant at intermediate damage levels. Results from elastic recoil detection analysis suggested that the implanted He atoms diffuse in a high-damage regime toward the surface.