In the field of photovoltaics, semiconductors of the III-V group such as GaAs and InP have been considered as the most efficient absorber materials due to their direct energy band gap and high mobility. In these compounds, arsenic and phosphorus are highly toxic and expensive. In this work we present systematic preparation of low cost SnS thin films and characterize these films to test their suitability for photovoltaic applications. We have observed that the films (with thickness ≅0.5μm) grown at the substrate temperature of 275°C exhibit a low resistive single SnS phase and have a direct optical band gap of 1.35eV with an absorption coefficient of ∼105cm−1. SnS films could be alternative semiconductor materials as absorbers for the fabrication of photovoltaic devices.

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SnS films with different thicknesses have been deposited on glass substrates at a constant substrate temperature of 300°C . The physical properties of the films were investigated using energy dispersive analysis of X-rays, X-ray diffraction, scanning electron microscopy, atomic force microscopy, van der Pauw method, and Fourier transform infrared spectroscopy measurements at room temperature. The deposited films exhibit only SnS phase with different orientations. We show that the electrical resistivity, activation energy, and optical bandgap of the films depend strongly on the preferred orientation of the SnS films. The electrical resistivity of films decreased with the increase of film thickness. The optical and electrical data of the SnS film are well interpreted with the composition, crystal, and surface structure data.

The effect of annealing on the composition, crystal structure, surface features and electro-optical properties of tin mono-sulfide (SnS) films, deposited by thermal evaporation at 300 • C, has been studied. Elemental analysis of the films shows sulfur deficiency, which increases at higher annealing temperatures (T a). The SnS structure in the as-deposited and annealed films remains orthorhombic. With an increase in T a , the grain size and the surface roughness are reduced. The electrical resistivity also decreases with increasing T a. The variation of activation energy and optical parameters with T a has been explained by taking into account the degree of preferred orientation of the grains. The films annealed at 100 • C show some unusual features compared to those annealed at other temperatures.