The impact of silver incorporation on the structural, morphological, and optical properties of spray-pyrolyzed cubic SnS thin films

Abstract

Cubic/ Pi-SnS phase has a strong optical absorption onset and larger dielectric constant, which is favorable for solar energy conversion. Hence, these cubic SnS phase films are gaining intense interest among the research community. However, the physical properties and thus its practical application heavily depend on the synthesis condition. We present here the effects of incorporation of silver (Ag) on the physical characteristics of cubic-SnS thin films synthesized by spray pyrolysis. Ag was incorporated at different atomic concentrations of 5, 10, 15, and 20% on cubic SnS thin films. A variety of methods were used to characterize and analyse Ag-incorporated thin films. Structural and vibrational properties were analyzed using X-ray diffraction (XRD) and Raman Spectroscopy, which shows that 5 at% Ag incorporated cubic-SnS have the most desirable properties. However, on higher incorporation of Ag, the deterioration of cubic SnS and formation of secondary phases (SnS2 and Sn2S3) is evident. The existence of Sn, S, and Ag ions in the necessary oxidation state has been confirmed by XPS analysis. A direct bandgap was observed in the region of 1.79 and 1.59 eV for the SnS and Ag: SnS thin films, respectively with the aid of Ultraviolet-Visible Spectroscopy (UV-Vis Spectroscopy). The Photoluminescence Spectroscopy (PL) showed the near-band edge emission peak for all the samples. The needle shape morphology was observed in Scanning Electron Microscopy (SEM) images and roughness variation was estimated using an optical profilometer.