Investigations on Fe doped SnS thin films by nebulizer spray pyrolysis technique for solar cell applications

Undoped and different concentrations of iron (Fe) doped tin sulphide (SnS) thin films were coated by nebulizer spray pyrolysis method with the substrate temperature of 350 °C. Polycrystalline nature of orthorhombic crystal structured pure and Fe doped SnS (Fe:SnS) thin films confirmed by X-ray diffraction (XRD) patterns. Structural studies further explored the preferential orientation of (201) plane for undoped SnS and their shifts to (400) and (111) directions for Fe:SnS at 6 and 10 wt. % of Fe concentration, respectively. The versatile route of structural modification has obviously demonstrated due to inclusion of Fe doping in SnS. Raman spectra further confirmed the structural variation of Fe:SnS. Topological variations obviously explained by atomic force microscopy images for pure and Fe:SnS. Optical results evidently claimed the deterioration of band gap values from 1.96 to 1.58 eV due to increase of Fe doping concentrations from 0 to 10 wt. %, respectively. Luminescence spectra showed a strong emission peak centered at 772 nm and low resistivity 3.32 x 10^-2 Ω cm with the high carrier concentration for 8 wt. % of Fe concentration using prepared Fe:SnS film. The fabricated solar cell device with n-CdS exposed the 0.18% of efficiency for p-Fe:SnS prepared using 8 wt. % Fe concentration.