The capability of hot-wire chemical vapor deposition (HWCVD, Cat-CVD) has been studied for the preparation of silicon-carbon alloy (Si1-xCx) films. The changes in deposition rate, carbon content, optical gap and IR absorption of Si-C and C-H-n are demonstrated for Si1-xCx alloy films deposited with the preparation conditions, gas ratio R=CH4/(SiH4+CH4+H-2) from 0.3 to 0.6, and filament temperature from 1750 to 2100 degreesC. A deposition rate over 0.9 nm/s is obtained for all samples. The samples have a heterogeneous structure, consisting of hydrogenated amorphous silicon-carbon alloy (a-Si1-yCy:H) and hydrogenated microcrystalline silicon ( Lc-Si:H). Impurity doping using B,H, gas has been tried for the sample with a carbon content of similar to 28%. The photoconductivity was measured, and the activation energy for the dark conductivity was 0.17 eV with the doping gas ratio, B2H6/(SiH4+CH4) of similar to0.054%.