Influences of native defect on bulk and surface electronic properties of SnS: an experimental and first-principles study

The semiconductor SnS is a promising candidate for a low-cost, earth-abundant, photovoltaic absorbing layer for thin film solar cells. An understanding of bulk and surface electrical properties would aid in comprehending transport behavior and, therefore, would be extremely useful for the fabrication of high-performance devices. In this context, anomalies in bulk and surface electrical properties of SnS were investigated using a combination of experiment and theory. In experiments, RF magnetron sputtering was used to fabricate single-phase polycrystalline SnS films, which were investigated for their detailed microstructure, optical properties, and electrical properties of bulk and surface SnS. First-principles density functional theory (DFT) computations of the bulk and surface SnS were employed to evaluate the electronic structures and analyze the observed anomalies in their bulk and surface electrical properties. The experimentally observed semi-metallic behavior utilizing scanning tunnelling spectroscopy was further addressed by DFT calculations on various native surface defects including vacancy, interstitials, and antisites.