Effect of Zn doping on optical properties and photoconductivity of SnS2 nanocrystalline thin films

Zn-doped SnS2 thin films have been deposited simply by spray pyrolysis technique. The doping level was changed from [Zn/Sn] = 0 to 7·5 at%. The films were characterized by means of X-ray diffraction, scanning tunneling microscopy (STM), energy dispersive X-ray analysis (EDX), photoluminescence and UV-Vis spectroscopy. XRD patterns of the films with different zinc contents show that all samples have polycrystalline structure with Berndtite dominant phase and preferred orientation of (001) growth plane. Zn insertion causes a significant decrease in grain size. Optical bandgap of the films have been calculated for different dopant concentrations and they lie in the region of 2·3–2·7 eV. Surprisingly, regardless of doping level, the luminescent properties of films are related to the fundamental bandgap energy and deep levels inside the bandgap. Photoconductivity of the films have been measured under visible light. Sensitivity to the light increases by zinc incorporation, which was a large amount for SnS2:Zn of 7·5%.