Damage in silicon carbide induced by Rutherford backscattering analysis

Damage in silicon carbide generated by ion implantation or irradiation is usually analyzed by Rutherford backscattering spectroscopy in combination with channeling (RBS/C) of MeV He+ ions, a technique which is considered to be largely non-destructive. In this paper we report on swelling of 6H-SiC induced by He+ implantation at doses commensurate with, or lower than those commonly used for obtaining RBS/C spectra of desirable statistics. The swelling increases by about 40% if the He+ ions are implanted in a non-channeling direction. The formation of high concentrations of deep-reaching (mu m range) defects due to RBS/C is confirmed by slow positron implantation spectroscopy (SPIS) measurements. An optical damage depth-profile, with distinct optical properties corresponding to the regions of electronic and nuclear stopping, is obtained from a fit to polarized infrared reflection spectroscopy (PIRR) data and compared to TRIM calculation. Auger electron spectroscopy (AES) shows that the specific color of the implanted area is not due to the deposition of a thin surface film during He+ implantation, and the swelling is not related to chemical reactions in the near-surface region. The formation of additional disorder from RBS/C may corrupt the respective data obtained subsequently by SPIS and PIRR. Therefore, RBS/C measurements should always be carried out last, i.e. following analytical techniques which are certainly non-destructive. (C) 1998 Elsevier Science B.V. All rights reserved.