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

Abstract

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 ( N S) 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 N S≈10 19 to N S=3×10 18 cm −3 and diminishes the room temperature dark conductivity by two orders of magnitude.