Effect of fabrication parameters on luminescent properties of ZnS:Mn nanocrystals

In this work, we mainly focused on the luminescence properties of ZnS:Mn nanocrystals. Various samples of ZnS:Mn have been characterized at different doping concentration, annealing temperature, spin speed and time. The present study shows the application of spin speed, spin time, doping concentration and temperature affect the luminescent intensity performance. Luminescent intensity becomes higher with the increasing film thickness. Spin speed and spin time are two major concerns for coating film to a demanded thickness on the glass slide. Film thickness is the main reasons of the increasing intensity with spin speed and time. Temperature dependent PL measurements provide thermally activated energy transfer from other defects to Mn²⁺ ions. As the temperature increase, the carriers can be trapped at Mn sites, enhancing the luminescence spectra. Meanwhile, the quenching process influenced the PL intensity with doping concentration. This process occurs at high Mn concentration which the energy transfer from Mn ions to the other nearest Mn atom is weak. Therefore, the luminescence of transition from ⁴T1 to ⁶A1 of ions becomes stronger. From this reason, it is shown that luminescent intensity increased with higher doping concentration but decreased with higher annealing temperature, spin speed and spin time during spin coating process.