Current transport in <i>a</i>-Si:Ge alloy Schottky barriers

Abstract

In this paper, we have investigated the temperature dependence of forward and reverse currents of a-Si:Ge:H-Pd barriers. In contrast to a-Si:H, we find that the diode quality factor is 2 and is independent of temperature. We have confirmed quantitatively that the forward current is recombination limited and the reverse current is generation limited. The barrier height ΦB=0.7 eV, which is half the measured optical gap. The frequency, bias, and temperature dependence of capacitance have also been investigated. From the capacitance measurements, we infer that the density of states near midgap is approximately 2×1017 cm−3 eV−1.