Electrochemical deposition of nanostructured SnS1−xTex thin films and their surface characterization

Abstract

Nanostructured SnS1−xTex (X = 0.0, 0.020, 0.027, 0.032, 0.036) thin films were deposited on fluorine doped tin oxide (FTO) substrates by an electrochemical route. The electrolyte contained SnCl2 (2 mM), Na2S2O3 (16 mM) and various amounts of TeO2 solution (4 mM) as a dopant. The electrochemical deposition was done under the same condition for all samples. The deposition potential (E), deposition time (t), pH and electrolyte temperature (T) were −1 V, 30 min, 2.1 and 60 °C, respectively. Only the concentration of Te-dopant was changed to prepare nanostructured SnS1−xTex thin films. The synthesized SnS1−xTex samples were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and room temperature photoluminescence (PL). The XRD pattern revealed that the nanostructured SnS1−xTex thin films were crystalline with an orthorhombic phase. The TEM images presented that the single crystals of SnS1−xTex nanostructures were almost spherical in shape. By X-ray peak broadening, the crystalline development in the SnS1−xTex nanostructures was studied. In order to check the individual contributions of crystalline sizes and lattice strains on the peak broadening of the SnS1−xTex nanostructures, the Williamson-Hall (W-H) analysis and size-strain plot (SSP) method were used. The physical parameters such as strain and stress values were calculated exactly for all the reflection peaks of XRD related to the SnS1−xTex nanostructures lying in the range of 20°–60°, from the W-H plot supposing a uniform deformation model (UDM) and by the SSP method. A relationship describing the particle size of SnS1−xTex samples was observed among the obtained results from the TEM, W-H analysis and SSP method. The PL results exhibited a good agreement with XRD pattern.