Effect of SnS thin film thickness on visible light photo detection

Abstract

In this study, SnS thin films of various thicknesses (500 nm–700 nm) were prepared by the thermal evaporation technique for potential photodetector application. High purity SnS prepared at 1000 °C is used to deposit thin films at room temperature. The prepared SnS thin films were characterized to assess the thickness effect on the crystallite size, morphology, transmittance, band gap, and photo-sensing properties. SnS pure phase confirmed through XRD and Raman spectral analysis. Among the fabricated SnS thin films, the sample having a thickness of 650 nm showed better crystallinity with higher crystallite size and preferred orientation of crystallites. SnS grew plate-like-columnar grain morphology of different widths and thicknesses which is confirmed by FESEM results. The UV–Vis studies showed a minimum band gap value obtained for 650 nm thickness film. The 650 nm thickness SnS films have a highest photo response of 6.72 × 10−1 AW−1, external quantum efficiency (EQE) of 157%, and detectivity of 14.2 × 109 Jones. The transient photo-response analysis showed the 650 nm SnS thin film has a 5.3 s rise and 5.1 s fall duration, which is better suitable for photodetector applications compared to other samples.