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The aim of the current research was to study regularities of chemical bath deposition (CBD) of tin sulphide thin films as function of tin and sulphur concentrations in the solutions. SnS thin films were deposited onto Mo-, ITO-and TO-coated glass and onto borosilicate glass substrates at room temperature for 24 hours. The concentrations of sulphur and tin (ratio 1:1) in the deposition solution were varied from 0.01 M to 0.09 M. Films were characterized by SEM and Raman spectroscopy. The structuraly best tin mono-sulphide films with good adhesion to the substrate were deposited at concentration of consituents in solution 0.03M. The films deposited at concentration of 0.01M had non-uniform and incomplete coverage of the surface on all used substrates whereas at tin and sulphur concentrations of 0.05M and higher films were peeling off of the substrate.

The influence of thermal treatment with the number of deposition cycles on the properties of SnS films on CdS and ZnS substrates was investigated. Annealing under an argon atmosphere made amorphous SnS films formed in one deposition cycle crystalline, but did not markedly change the crystallinity of SnS films formed after multiple deposition cycles. All annealed films were consistent with the orthorhombic phase of herzenbergite SnS, and no additional Sn-containing phases were identified. The CdS/SnS films maintained their initial stoichiometric composition of tin monosulphide after annealing. The films deposited on ZnS substrate films were rich in tin and poor in sulphur and their composition was unaffected by thermal annealing. Both the deposited and thermally annealed films possessed uniform pinhole-free surfaces. Only minor changes in the optical transmittance and reflectance spectra of the CdS/SnS films were observed after annealing, whereas the spectra of the ZnS/SnS films exhibited substantial changes after annealing. As the annealing temperature increased, the absorption edge of the ZnS/SnS films shifted to a longer wavelength. The optical bandgap of the CdS/SnS films was indirect and decreased from 1.28 eV for the three-depositioncycle CdS/SnS film to 1.22 eV after annealing at 460 °C. The ZnS/SnS films showed a similar change: the bandgap of 1.39 eV for the unannealed films decreased to 1.23 eV after annealing. All deposited and annealed SnS films showed p-type conductivity and their photoconductivity increased with the increasing annealing temperature. Solar cells with reverse structures were fabricated; their performance decreased with the increasing annealing temperature of the SnS film.

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