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.