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, J
sc
, V
oc
, FF and efficiency, are independent of thickness of the undoped layer if film thickness is larger than the depletion region width. J
sc
and V
oc
are 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.