The ADHT (alternately repeating deposition and hydrogen plasma treatment) method and the DLE (deposition of low emission) method were developed for the formation of high quality a-SiGe:H (hydrogenated amorphous silicon germanium) films. High photosensitivity was obtained by the ADHT and DLE methods, with a wide range of optical bandgaps between 1.3 eV and 1.7 eV, higher than those of films obtained by the hydrogen dilution method. It was also proved that these films were solar cell device-grade. A conversion efficiency of 8.9% was obtained with a bandgap of 1.6 eV by the ADHT method, and a conversion efficiency of 8.2% and a short circuit current of 20.4 mA/cm 2 were obtained with a bandgap of 1.47 eV by the DLE method.