The effect of Mn2+ doping concentration on the optical and optoelectronic properties of ZnS thin film

Over the years, Manganese doped Zinc sulfide thin films have gained immense attention as an ion-doped semiconductors due to wide range of tunable electrical and optical properties. This paper concerned detailed structural, optical and electrical studies of ZnS thin film, both pure and doped with Mn2+ ions, successfully deposited via spray pyrolysis method on Si and glass substrate at different concentration of Mn ions (Mn molar fraction, x = 0.0, 0.05, 0.1, 0.15). The effect of various concentration of Mn ions on the morphology and optical properties of the Mn doped ZnS thin films were studied as well as electrical and photo detection characteristics were investigated by analysis of as-prepared thin films’ I-V curves. Produced nanocrystalline films were systematically characterized by employing the following characterization techniques such as X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Ultraviolet-Visible (UV-Vis) spectroscopy and Photoluminescence (PL) spectra measurements. The results showed that the Mn doping concentration can affect the microstructure, photoluminescence, absorption spectra and hence, electrical properties of the films. XRD pattern revealed that the films are pure β-phase. UV-Vis spectra demonstrated that absorption shoulders of the doped films were red-shifted as compared to pure ZnS owing to decrease in the energy band gap as the Mn concentration increases. SEM showed a homogeneous morphology and dense layers. PL spectrum also exhibited an orange-red emission at 635 (nm) due to the 4T1-6A1 transition in Mn. The PL intensity increased with increase in the Mn ions concentration. Optoelectronic characterizations showed that the doping of Mn ions improve the photosensivity of the ZnS based thin films.