Spin defects and transport in hydrogenated nanocrystalline silicon carbide films produced by photo-CVD technique

Hydrogenated nanocrystalline silicon-carbide (nc-SiC:H) films with a varied carbon content have been prepared by a mercury-sensitized photo-assisted chemical vapor deposition (photo-CVD) technique. The structural analysis by Raman spectroscopy and X-ray diffraction indicated that the deposited material is composed of nanocrystalline silicon grains embedded into an amorphous matrix. The transport behavior and spin defect densities (NS) of the films have been investigated by temperature dependent conductivity and electron spin resonance (ESR). It was found that during nc-SiC:H film growth the increase in carbon content (C-content) hinders the growth of a crystalline fraction. The decrease in film crystallinity caused by C-content increase (from 5 to 12 vol%) is accompanied by the decrease in spin densities from NS≈1019 to NS=3×1018 cm−3 and diminishes the room temperature dark conductivity by two orders of magnitude.