Raman spectroscopy of ion irradiated SiC: chemical defects, strain, annealing, and oxidation

TL;DR

This study uses Raman spectroscopy to analyze chemical defects, strain, oxidation, and annealing effects in ion-irradiated SiC crystals, revealing defect structures, residual stresses, and oxidation phenomena.

Contribution

It provides detailed insights into defect structures and stress states in SiC post-irradiation and annealing, highlighting chemical defect roles in radiation damage.

Findings

Neon and silicon ion irradiation cause distinct defect structures.

Ion irradiated SiC exhibits less tensile strain than neutron irradiated samples.

Oxidation occurs during high-temperature ion implantation, evidenced by C-O and Si-O signals.

Abstract

Raman spectroscopy has been used to identify defective bonding in neon and silicon ion irradiated single crystals of 6H-SiC. Observable differences exist in the C-C bonding region corresponding to different defect structures for neon and silicon ion implantations. Raman spectra of ion irradiated SiC show less tensile strain than neutron irradiations, explained by a residual compressive stress caused by the swelling constrained by the undamaged substrate. Evidence of oxidation during high temperature ion implantation is observed as C-O and Si-O Raman signals. Annealing irradiated SiC while acquiring Raman spectra shows rapid recovery of Si-C bonding, but not a complete recovery of the unirradiated structure. Annealing irradiated SiC causes surface oxidation where unirradiated SiC does not oxidise. Comparisons are made to the apparent radiation resistance of diamond and silicon which have similar crystal structures, but are monatomic, leading to the suggestion that chemical defects are responsible for increased radiation damage in SiC.