Influence of sulfur concentration on phase formation in SxnSy thin films deposited through nebulizer spray pyrolysis technique

Abstract

This research utilizes a precursor solution of SnCl₂ and SC(NH₂)₂ at varying sulfur concentrations of 0.5, 0.6 and 0.7 M to fabricate Sn_xS_y films through the nebulizer spray technique to establish the role of sulfur concentration on its phase formation. The crystallographic structure, morphology, optical and electrical properties of the deposited films were analyzed using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, UV-Vis spectroscopy and four probe measurements. X-ray diffraction analysis revealed the crystalline phases present in the films, with distinct peaks corresponding to various phases of Sn_xS_y, indicating the successful incorporation of sulfur at different concentrations. Scanning electron microscopy provided insights into the surface morphology, demonstrating uniform film deposition and varying grain sizes and shapes influenced by sulfur concentration. Energy dispersive X-ray spectroscopy confirmed the elemental composition of the films, with the ratio of tin to sulfur aligning with the initial concentrations in the precursor solution. Optical measurements through UV-Vis spectroscopy indicated enhanced light absorption properties with increasing sulfur content, the value of band gap reaching a minimum of 1.31 eV for higher molar concentration of sulfur which is found to be beneficial for photovoltaic applications. Finally, four probe measurements determined a maximum electrical conductivity of 2.18 × 10^− 8 Ω^-1cm^-1 and a highest charge carrier mobility of 6.54 × 10¹⁵ cm^-1 for 0.7 M revealing the influence of sulfur concentration variation on the electrical properties of the prepared films. The findings suggest that tuning sulfur concentration can optimize the properties of Sn_xS_y films to enhance its performance in photovoltaic applications.