Effect of carrier gas pressure on structural, optical and photovoltaic properties of tin sulphide thin films prepared by nebulizer spray pyrolysis method

Abstract

Tin sulphide (SnS) thin films deposited using nebulizer spray pyrolysis technique by changing pressure (0.1, 0.15, 0.2 and 0.25 Pascal) at $$350^{\circ }\hbox {C}$$ and their characterization are reported. The influence of carrier gas pressure on structural, morphological, optical and electrical properties of the film are determined using X-ray diffraction (XRD), energy-dispersive X-ray, atomic force microscopy, UV–Vis spectrophotometry and Hall effect measurement. Structural parameters such as pole density, orientation factor, crystallite size, micro strain and dislocation density were analysed using XRD data. The scanning electron microscopy studies display superior morphology and surface roughness of the films which were found to increase with pressure. Optical studies on the films revealed a variation in band gap from 1.78 to 1.66 eV for were the raise of pressure from 0.1 to 0.2 Pa. A single strong emission peak at about 825 nm is observed in photoluminescence spectra with enhanced intensity which may be attributed to near band edge emission. Grown SnS thin film exhibits p-type conductivity, which was confirmed from the Hall effect measurement. The low resistivity and higher carrier concentration are found to be $$0.235\,\Omega \,\hbox {cm}$$ and $$5.04\times 10^{18}\,\hbox {cm}^{-3}$$ , respectively. These properties were then correlated with the deposition parameters. Furthermore, to study the photovoltaic properties of SnS thin films, a heterojunction solar cell FTO/n-CdS/p-SnS/Al was fabricated showing conversion efficiency of 0.16%.