Synthesis and characterization of some ZnS-based thin film phosphors for electroluminescent device applications

ZnS:Mn, ZnGaS:Mn and ZnS:CuCl2 phosphor thin films for alternating-current thin-film electroluminescent (ACTFEL) devices were prepared by thermal evaporation from two and three sources, respectively. Films are polycrystalline, strongly oriented and stoichiometric or nearly stoichiometric with high optical transmission in the visible part of the spectrum. The band gap of ZnS:Mn, ZnGaS:Mn and ZnS:CuCl2 films was found to be 3.63, 3.86 and 3.56 eV, respectively. The sheet resistance of the ZnS:Mn and ZnGaS:Mn films was greater than 100 MΩ. The resistivity of ZnS:CuCl2 films was between 1.5–80 Ω cm. Photoluminescent (PL) and electroluminescent (EL) characteristics were also studied. The results indicate that after the optimization the investigated phosphor thin films will be suitable for ACTFEL device applications.