Effect of Ag doping on the physical properties of tin-sulfide thin films for optoelectronic applications prepared by spray pyrolysis

Abstract

Silver-doped tin-sulfide thin films were deposited on glass substrates at 400 °C through spray pyrolysis. Afterward, the effects of Ag doping on the structural, optical, and electrical properties of thin films were investigated. The precursor solution was prepared by dissolving tin chloride (SnCl4∙5H2O) and thiourea (CS(NH3)2) in deionized water and subsequently adding silver acetate (AgC2H3O2). SnS2:Ag thin film was prepared with $$\frac{{\left[ {{\text{Ag}}} \right]}}{{\left[ {{\text{Sn}}} \right]}}$$ % of 1, 2, and 3 at.%. X-ray diffraction analysis showed that the thin film exhibited a preferred (001) orientation in the SnS2 phase, and the intensity of the (001) peak increased with increased Ag-doping concentration. In addition, scanning electron microscopy indicated that the thin films presented spherical grains. Increased doping concentration also resulted in a decrease in the single-crystal grain size from 14–6 nm, with an average grain size of 80–123 nm. Moreover, the optical bandgap decreased from 2.75 to 2.56 eV, and the carrier concentration decreased from 95.48 × 1015 cm−3 to 2.48 × 1015 cm−3. On the contrary, the Hall mobility increased from 59.725 to 183.28 cm2/v s. The electrical resistance also increased from 1.096 to 13.75 Ω cm. Hall effect studies revealed that the films exhibited n-type conductivity.