Controlled growth, structure and optical properties of Fe-doped cubic pi-SnS thin films

In this paper, the structural, surface morphology and optical properties of Fe-doped cubic tin sulfide (pi-SnS) films are reported. The Fe-doped (0.0-10.0 by wt.% Fe in SnS) pi-SnS films are grown on glass substrate by chemical bath deposition. Microstructural and optical properties of all films are studied by X-ray diffraction (XRD), atomic force microscopy (AFM) and UV-Vis/NIR spectroscopy. XRD spectra confirm the formation of single phase in all Fe-doped SnS films. All Fe-doped SnS films exhibit simple cubic (pi-SnS) phase. The crystallite size decreases (40 2 nm - 23 +/- 1 nm) with the increase in Feconcentration. FTIR spectra indicate the Sn-S bond stretching around 863.47 cm(-1), 750.39 cm(-1) and 554.50 cm(-1). Surface AFM images reveal a uniform distribution of spherical grains (in 0.0% Fe doped pi-SnS film) with small voids. However, formation of small clusters and nucleation of islands are observed in all Fe-doped pi-SnS films. All films have high absorption coefficient (alpha similar to 10(4)cm(-1)). From optical measurements, all films are found to exhibit direct band gap, E-g. The calculated band gap, E-g is found to decrease (1.74 eV-1.63 eV) with increasing Fe-concentration. The results indicate that the E-g is possible to tune (over a narrow range) for optical device applications by controlling the microstructure and phase of Fe-doped pi-SnS films. (C) 2018 Elsevier B.V. All rights reserved.