ESR and photoluminescence properties of Cu doped ZnS nanoparticles

Nanoparticles of Zn 1− x Cu x S with Cu concentrations of x = 0.0, 0.1, 0.2, 0.3 and 0.4 were prepared by a co-precipitation reaction method from homogeneous solutions of zinc and copper salts. Both the ZnS and ZnS:Cu nanoparticles excited at about 370 nm exhibits a broad green emission band peaking around 491 nm, which confirms the characteristic feature of Zn 2+ as well as Cu 2+ ions as luminescent centers in the lattice. The TEM micrographs showed spherical morphology for ZnS nanocrystals and the average size of the particles was estimated to be around 8.5 nm. At liquid nitrogen temperature, ESR signal characteristic of Cu 2+ ions was observed in samples of all concentrations. ESR spectra analysis also indicated that Cu 2+ ions enter the host lattice by replacing Zn 2+ ions with distorted tetrahedral site symmetry.