Chemical bath deposition of Mn-doped ZnS thin films using greener complexing agents: Effect of Mn-doping on the optical properties

Manganese (Mn)-doped ZnS thin films were deposited by chemical bath deposition using a greener complexing agent, trisodium citrate. The effects of the Mn-doping concentration on the structural, optical and photoluminescence properties of Mn-doped ZnS thin films was investigated in the range, Mn = 0-12 at.%. The doping concentration of Mn was measured by inductively coupled plasma-atomic emission spectroscopy and energy dispersive X-ray spectroscopy. Morphological analysis showed that the shape of the grains over the substrate surface was changed from angular to round with increasing Mn-doping concentration. Structural analysis revealed cubic ZnS in the entire range of targeted Mn-doping concentration. The band gap of the films was calculated using optical transmittance data that varied in the range, 3.68-3.81 eV, according to the Mn-doping concentration. The room temperature photoluminescence spectra of these samples exhibited a broad, intense blue and orange emissions. A strong emission band centered at 585 nm suggests the successful incorporation of Mn2+ ions into the ZnS lattice. A high photoluminescent yield was observed for an optimum doping concentration of 6 at.% Mn.