Relaxation phenomena in keV-ion implanted hydrogenated amorphous silicon carbide

Infrared spectroscopy was used in order to monitor the relaxation phenomena in amorphous silicon carbide induced by hydrogen introduction. Amorphous silicon carbide (a-SiC) thin films (90 nm) were prepared by high fluence implantation (3×1017 ions cm−2) of C ions in silicon. To obtain hydrogenated (a-SiC:Hx) films hydrogen ions were also implanted at different fluences and the hydrogen fraction ranges from x=0.1 to x=1.0. The bonding structure was studied by infrared spectrometry, following the stretching mode vibration of Si–C, Si–H and CHn bonds. Hydrogen introduction in amorphous silicon carbide produces a decrease of width and of IR absorption cross section of Si–C mode, both effects being related to a decrease of disorder of the amorphous phase. The main role of hydrogen is the rearrangement of bonds, the saturation of dangling bonds and the reduction in the number of defects, which relax the structure of the amorphous material.