Helium effusion measurements for studying the microstructure of a-SiC:H films deposited by d.c. sputtering

Abstract

The effusion of helium was used for microstructure characterisation of d.c. sputtered amorphous silicon carbon (a-SiC:H) alloys. The results show that up to carbon concentrations of approximately 25 at.%, helium effuses mainly in two stages: a lower temperature effusion peak near 500 °C is attributed to the out-diffusion of He from network sites while higher temperature He effusion is attributed to the release of He precipitated in isolated voids present from the deposition process. At carbon concentrations exceeding 25 at.%, helium is found to effuse predominantly in a single stage at lower temperature indicating the presence of interconnected voids. The results are in agreement with effusion results of implanted neon, argon as well as hydrogen.