The defect structure for Cu2+ in CdSe nanocrystals was theoretically studied by analyzing the spin Hamiltonian parameters of this impurity center. This center was ascribed to Cu2+ occupying the octahedral interstitial site, rather than the tetrahedral substitutional Cd2+ site proposed by previous work. The Cu2+ center exhibited slight tetragonal elongation distortion (characterized by the elongation parameter ρ≈0.03) due to the Jahn–Teller effect. The theoretical spin Hamiltonian parameters and optical transition showed good agreement with the experimental data. The above unusual defect structure (occupation and symmetry) for Cu2+ in CdSe nanocrystals was discussed, as compared with the conventional trigonally distorted tetrahedral Cu2+ centers in bulk II–VI semiconductors.

Studies on the Defect Structure for Cu2+ in CdSe Nanocrystals. S.Y.Wu, H.M.Zhang, P.Xu, S.X.Zhang: Spectrochimica Acta A, 2010, 75[1], 230-4