Investigating the Effects of Ag and Zn Metals as Pre-coating with Annealing on Physical Properties and Applications of MnS Thin Films

Abstract

For this study, we used thermal evaporation to synthesize thin films of manganese sulfide (MnS) with a layer of zinc and silver pre-coating. A range of methods, including UV/VIS/NIR spectrophotometry, EDX, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and the two-probe technique, were employed to examine the structural, morphological, optical, and electrical characteristics of the as-deposited and annealed films. Additionally, the films were annealed for 20 min at 300°C. Numerous parameters were found, including the dispersion parameters, activation energy, mobility, refractive index, extinction coefficient, Urbach energy, dielectric constants, and optical energy gap. The pure MnS, metal/MnS, and annealed metal/MnS films had an amorphous structure. There was a direct allowed transition between the films with different pre-coating layers. The energy gaps were 3.17 eV for MnS, 2.57 eV for Ag/MnS, 2.52 eV for Zn/MnS, 1.9 eV for annealed Ag/MnS, and 2.6 eV for annealed Zn/MnS. Besides, the pre-coating layer affected the refractive index dispersion of the films. In addition, the addition of the pre-coating metal resulted in lower film resistivity, indicating semiconductor behavior in the samples. Finally, we tested deposited and annealed Ag/MnS films for sensing I2 and Co2. As a result, deposited Ag/MnS has a promising future for gas sensing applications. In addition, we tested annealed Zn/MnS for organic pollutant decomposition, which demonstrated high efficiency of approximately 81%.