Synthesis of Mn-Doped ZnS for UV Photodetector Applications: Physical, Optoelectronic, and Luminescent Properties

In this study, zinc sulfide (ZnS) and manganese (Mn)-doped ZnS nanopowder were successfully prepared via a simple and cost-effective chemical precipitation method with various concentrations of Mn for use in UV photodetectors. The effects of Mn doping on the structural, morphological, and optoelectronic properties of ZnS nanopowder were studied. Structural analysis showed that all samples had a cubic structure with crystallite sizes approximately in the region of 2–3 nm. The morphological analysis using scanning electron microscopy confirmed the formation of well-dispersed spherical nanoparticles. Photoluminescence spectra show that Mn doping increased the luminescence intensity and caused a red shift in the emission peaks. Electrical properties such as conductivity and dielectric constant showed marked improvement with increasing Mn content. The conductivity increased from 3.7 mΩ−1·m−1 for pure ZnS to 6.3 mΩ−1·m−1 for the 1.03 mol% Mn2+ sample. The performance of photodetectors was evaluated under UV light. It was revealed that the photodetector based on a sample with 1.03 mol% Mn2+ reached an optimum state with an EQE of 9.8%, a detectivity of 4.65 × 109 Jones, and a responsivity of 3.64 × 10−2 A/W, indicating the effectiveness of Mn doping in improving the photo-generated carrier collection.