Effect of thermal annealing on nebulizer spray deposited tin sulfide thin films and their application in a transparent oxide/CdS/SnS heterostructure

Tin sulfide (SnS) thin film was deposited on glass substrates using simple nebulizer spray pyrolysis method. The influence of vacuum annealing on structural, optical, morphological, electrical and photovoltaic properties of the films were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy, atomic force microscopy, energy dispersive analysis of X- ray, UV-Visible spectrophotometry, photoluminescence spectrofluorometry and Hall measurements. Structural parameters such as lattice structure, crystallite size, micro strain and dislocation density were estimated using XRD analysis. There was a notable enhancement in morphology and surface roughness of the films and they were found to vary with respect to the annealing temperature. Optical studies done on the films revealed a decrease in energy gap for the increase of annealing temperatures. From the Hall effect study, it was found that SnS thin films have p-type conductivity. The lowest resistivity and higher carrier concentration were found to be 0.074 Ω cm and 1.07 × 1019 (cm−3) respectively. A heterojunction solar cell, CdS/SnS was fabricated and its solar conversion efficiency obtained was about 0.73% for tin sulfide films annealed at 400 °C.