Noticeable photo-sensing properties of SnS:Cu thin films fabricated by thermal evaporation technique

Abstract

Due to their optoelectronic behavior, superior optical absorption, and tunable band-gap energies, metal chalcogenides have attracted global attention in recent decades. SnS (tin sulfide) crystals, in particular, have drawn a lot of interest because of their prospective applications in photovoltaics, photo-detectors, field-effect transistors, and holographic recording systems. Thermal evaporation technique was employed to develop the SnS:Cu thin films on glass substrates by varying 1 to 4 wt% of the Cu doping concentration. XRD, Raman, FESEM, UV–Vis/NIR Spectrometer, and photo-sensing measurement System were used to analyze the films structural, optical, and electrical properties. The films exhibit a polycrystalline morphology of orthorhombic SnS structure with the crystalline structure orientated in the same direction along the (111) plane. The XRD spectra demonstrated that Cu doping concentrations up to 2% improve preferential orientation and crystalline quality, whereas the increase in Cu dopant concentration above 2% affects the orientation of the peaks and quality of the crystals. The estimated direct bandgap Eg of the SnS:Cu films falls with increasing Cu-doping concentration, reaches a low value of 1.53 eV with 2% Cu, and thereafter increases. Scanning electron microscopy was used to evaluate the surface morphology, and average grain size of SnS:Cu thin films (SEM). Due to their high Responsivity (2.92 × 10−2 AW−1), External quantum efficiency (6.8%), and Detectivity (1.20 × 109 Jones) characteristics, the 2% Cu doped SnS film may be better suitable for photosensor devices.