Characterization of luminescence centres in neodymium implanted zinc sulphide

Analysis of the cathodoluminescence emission spectra of neodymium implanted cubic single crystal ZnS as a function of post-implantation annealing temperature has enabled groups of emission lines to be identified as originating from transitions within particular luminescence centres. For each group of lines the wavelength separations yield energy splittings characteristic of the crystal field at the luminescence centre. Comparison of these splittings with values calculated by crystal field theory on the basis of a point charge model, with due regard to possible sites of cubic symmetry in ZnS, has allowed two luminescence centres (A and B) to be identified.Centre A, which exists at low annealing temperatures, consists of a Nd³⁺ ion situated interstitially with 4 tetrahedrally disposed nearest neighbour S^2? ions. At higher annealing temperatures the emissions from centre A were found to decline giving way to those of centre B, which analysis shows to be a Nd³⁺ ion situated on a zinc substitutional site.