During the last decades, a-Si:H alloys have proven to be materials with a range of potential application including solar cells.Despite the success of a-Si:H alloys in solar cells, fundamental problems with regard to the improvements of the efficiency and the long-term stability of the material have not been solved due to the Staebler-Wronski effect (SWE).In the present work, chalcogen (S/Se) doped amorphous hydrogenated silicon (a-Si,S/Se:H) films were prepared by the conventional plasma enhanced chemical vapor deposition (PECVD) technique.Both Se and S doped a-Si:H films have band gaps that range from 1.7 to 2.0 eV, as a function of doping concentration.The photo response and intensity variation of photoconductivity (PC) of the films were determined by illuminating with white light of 100mW/cm2 intensity.The optical properties such as absorption coefficient, photoconductivity (PC), PPC and photo-degradation of S-and Se-doped a-Si: H films have been measured to determine the suitability of these materials for photovoltaic devices.The variation of the excess conductivity with exposure time at room temperature was measured by exposing the sample to light for various irradiation times.Further, effect of annealing on the optical properties of a-Si,S/Se:H films also carried out after annealing the samples in vacuum (10-6 torr) in the temperature range from 1000C to 5000C.The persistent photoconductivity (PPC) measurements at room temperature showed that PPC increased with increasing irradiation time.Photo degradation results indicate that a-Si,S/Se:H system would be more stable than the its counterpart a-Si,C:H system as the compensation of the photo degradation due to PPC is larger in the case of S/Se doped a-Si:H films.