The photoluminescence intensity has been measured as a function of time for a-Si:H films deposited by varying substrate temperature, doping concentration, and discharge geometry. The ratio of luminescence intensity measured after light exposure to that before exposure increases monotonously with the substrate temperature between 130 and 350 degree C and decreases as the hydrogen concentration is increased from 4 to 19 atomic % in the films deposited at 310 degree C. The luminescence fatigue time decreases as the substrate temperature is lowered, but is independent of the hydrogen and doping concentrations when the substrate temperature is fixed. The results indicate that the mechanism to interpret the light induced effects should involve the hydrogen.