Current-voltage analysis of a-Si:H Schottky diodes

Direct current (dc)-voltage (I-V) characteristics of the hydrogenated amorphous silicon (a-Si:H) Schottky diode have been measured at different temperatures under dark and light. From the fourth quadrant of illuminated characteristics, fill factor (FF) values were obtained for each temperature measured (173-297 K). We have found that FF increases very little as the temperature is decreased. The measured data from I-V characteristics has been analyzed in detail. In particular, from dark I-V characteristics obtained, the density of state (DOS) near the Fermi level was determined using a simple model based on the space-charge limited current (SCLC). On the other hand, from the illuminated I-V characteristics, the density of carriers was calculated for each temperature using the analysis of diode equation as known. A comparison of the carrier density and the measured photocurrent as a function of the reverse temperature was also made and a good correspondence was obtained.