Intensity and temperature dependence of photocurrent of a-Si:H Schottky diodes

The photocurrent of hydrogenated amorphous silicon (a-Si:H) Schottky diode has been studied as a function of light intensity from a HeNe laser, applied electric bias, and temperature, by using a constant photocurrent method. The I–V characteristics and thus fill factor (FF) values were also obtained over the temperature range 173–297 K. The FF increases very little as the temperature is decreased. The exponent γ in the power relationship Iph ∼ Gγ between photocurrent and light intensity was found to be temperature and electric field dependent, and peaked around 260 K measured. The activation energy obtained from thermally activated photocurrent was also found to be electric field dependent. These experimental results are discussed by means of the influence of the trapping of charge carriers on the electric field profile.