Effects of the undoped layer on characteristics of amorphous silicon Schottky diodes

The effects of undoped layer thickness on the dark and illuminated I-V characteristics of hydrogenated amorphous silicon Schottky barrier solar cells are investigated. Schottky barrier (S.B.) metals having different work function (Cr and Pd) were deposited on the 0.22 µm - 1.45 µm thick a-Si:H films. Photovoltaic performance, Jsc, Voc, FF and efficiency, are independent of thickness of the undoped layer if film thickness is larger than the depletion region width. Jscand Vocare controlled by S.B. metal and FF is independent of S.B. metal. Dark I-V characteristics depend on both S.B. metal and device thickness suggesting a barrier controlled space charge limited phenomena. Variation of turn-on (threshold) voltage with undoped layer thickness can be applied to the design of switching and memory devices.