We fabricated a a-SiC:H / a-SiGe:H / a-Si:H thin film solar cell by adjusting CH4 flow rate in order to absorb long wavelength of solar spectrum without stacked structures such as triple junctions. The a-SiC:H, a-SiGe:H and a-Si:H layers with sheet resistance 7 similar to 8 ohm/sq were deposited on indium tin oxide (ITO) glass by 13.56 MHz radical-assisted plasma-enhanced chemical vapor deposition (RA-PECVD). The working pressure and substrate temperature were 750 mTorr and 250 degrees C, respectively. The a-SiC:H films for p-layer thickness of 300 angstrom were deposited using 10% CH4 diluted in H-2. The thickness of a-SiGe:H for i-layer corresponded to 2000 angstrom. The n-layer was fabricated using 1% PH3 in diluted H-2. The optical properties of these films were measured by UV-VIS spectrophotometer. The thickness of the film was estimated by FE-SEM were observation. The various values of Jsc, Voc, FF and conversion efficiency were evaluated by the solar simulator.