Characteristics of metal/p-SnS Schottky barrier with and without post-deposition annealing

With growing interest in SnS for solar photovoltaic device fabrication, the barrier characteristics to this semiconductor with respect to different metal contacts have become increasingly important. In this work we have studied barrier characteristics of polycrystalline SnS thin films metallized with indium, aluminium, copper and silver under different annealing conditions. Indium has been observed to form ohmic contact to p-SnS under all annealing conditions. With the other three metals, Schottky diodes were fabricated and subsequently the contact parameters were extracted under forward bias using indium top contact under different annealing conditions. Although aluminium formed Schottky contact to polycrystalline SnS, annealing at 350 °C rendered it ohmic. EDX analysis confirmed desulfurization from SnS thin films due to annealing. Breakdown voltages of the Al/SnS Schottky barrier diode were determined and were in the decreasing trend with higher annealing temperature, supporting the increase in the doping profile with annealing temperature. Photoluminescence spectra of SnS films were studied and correlated to surface trap centers generated due to annealing.

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