Resonant tunneling via localized states in the photocurrent yield of Pd/amorphous silicon Schottky barriers

Abstract

A theoretical analysis of the effect of resonant tunneling via localized tail states on the photocurrent yield in Pd/hydrogenated amorphous silicon (a-Si:H) Schottky barriers is presented in terms of the transfer matrix approach. We use a single empty state with δ-type potential within the barrier. By adjusting the strength ( Ω 1 ) of the δ function, the barrier height θ b and the position χ 1 of the localized state, we fit the curves of the square root of the photocurrent yield as a function of photon energies for samples with different density of states in the gap. We find that the contribution of the resonant tunneling to the photocurrent yield is remarkable, in particular for the low photon energy region. It implies that the resonant tunneling effect is very important on the experimentally determined value of the barrier height.