INVESTIGATION OF THE DEFECT STRUCTURE, OPTICAL AND EPR SPECTRA FOR CdS: Ti2+ AND CdSe: Ti2+ CRYSTAL

The optical spectral band positions and spin-Hamiltonian parameters (g factors g(parallel to), g(perpendicular to) and zero-field splitting D) of CdS: Ti2+ and CdSe :Ti2+ crystals are calculated from the complete diagonalizaion (of energy matrix) method based on a two-spin-orbit parameter model for 3d(2) ions in trigonal symmetry. In the model,both the contribution to spin-Hamiltonian parameters due to the spin-orbit parameter of central 3d(2) ions and that of ligand ions are included. The crystal field parameters used in the calculations are obtained from the superposition model which enables correlation of the optical and EPR spectral data with the defect structure of the studied paramagnetic impurity centers in crystals. From the calculations, the defect structures of Ti2+ centers in CdS: Ti2+ and CdSe: Ti2+ are acquired, the signs of zero-field splittings D are suggested,and the optical band positions and spin-Hamiltonian parameters are explained. The results are discussed.