Infrared absorption and hydrogen effusion were measured on silicon rich a-SiC:H films deposited by d.c. sputtering. Hydrogen concentration was changed by hydrogen implantation. The results show that the shift of the Si-H stretching absorption from 2000 to 2100 cm-1 with increasing carbon concentration is mainly due to hydrogen-related void formation. The absorption strength of Si-H stretching and wagging absorptions are found to be independent of carbon concentration. The data suggest that both 720 and 780 cm-1 absorptions are due to C-Si stretching vibrations with the 720 cm-1 absorption presumably related to H-Si-C groups. Under the deposition condition applied, these H-Si-C groups are the predominant sites for hydrogen and carbon incorporation.