Investigation of structural and optical properties of Mg doped ZnS thin films prepared by Mist-CVD technique: Experimental and theoretical aspects

Abstract

In the present study, undoped and magnesium (Mg)-doped zinc sulfide (ZnS) thin films were prepared using the low-cost Mist CVD technique on a soda-lime glass substrate in a reactor chamber maintained at a high temperature of 450 °C ± 10 °C. The structural, vibrational, chemical compositional, morphological, optical and electric characteristics of the prepared Zn1-xMgxS thin films were studied using X-ray diffraction (XRD), Raman spectroscopy, energy dispersive spectrometer (EDS), scanning electron microscopy (SEM), photoluminescence emission (PL), atomic force microscopy (AFM) analysis, and Hall effect measurements. The aim of the present work is to examine the effect of incorporation of Mg into ZnS thin films matrix. XRD and Raman spectroscopy investigations confirmed the formation of polycrystalline micro structured films. The presence of Zn, S, and Mg elements was confirmed by EDS Analysis. The growth of the surface roughness of the films with increasing Mg content, as well as the crystalline size lead to a higher carrier concentration (5.103 × 1018 cm−3), and lower resistivity of the thin films (5.021 × 10−3 Ω cm). Furthermore, DFT investigation of the electronic properties using the GGA/PBE + U functional provides a detailed explanation of the band structure and confirms the band gap reduction after doping wurtzite ZnS with Mg (12 at.%). Therefore, the outcome of this of this study might provide an experimental and theoretical background for future research on Mg-doped ZnS.