The structural and optical properties of hydrogenated amorphous silicon carbon (a-SiC:H) thin films, grown from pure SiH4, C2H2 and H-2 mixture by hot wire chemical vapor deposition (HWCVD) technique, were studied. Variable flow rates and other growth conditions were applied. A variety of techniques, including X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, Raman scattering (RS), Atomic force microscopy (AFM), UV-VIS-NIR spectroscopy and photoluminescence (PL) were used to characterize the grown materials. The results confirmed coexisting of the multiphase structure of the grown a-SiC:H thin films: Si-C network, carbon-like and silicon-like clusters. The room temperature (RT) PL shows a different result from the previous reports. It is suggested that both graphite-cluster phase and silicon cluster like phase are light-emitting grains. The two types of grains and Si-C network are the origin of the PL in hydrogenated amorphous silicon carbide material. (c) 2005 Elsevier B.V. All rights reserved.