Optical properties of undoped and Co-DOPED CdIn 2Se 4 single crystals

Abstract

CdIn 2Se 4 and CdIn 2Se 4:Co 2+ single crystals were grown by the vertical Bridgman technique. The grown single crystals were pseudocubic in structure and their lattice parameters were a = 5.811 A ̊ for CdIn 2Se 4 and a = 5.795 A ̊ for CdIn 2Se 4:Co 2+ . The direct and indirect energy gaps are found to be 1.67 and 1.55eV, respectively for, CdIn 2Se 4, and 1.58 and 1.27eV for CdIn 2Se 4:Co 2+ at 293 K. In CdIn 2Se 4:Co 2+, nine impurity optical absorption peaks due to cobalt are observed. These peaks can be attributed to the electronic transitions between the split energy levels of Co 2+ ions located at the T d symmetry site of CdIn 2Se 4 host lattice. The crystal field, Racah, and spin-orbit coupling parameters are given as Dq = 407cm −1, B = 553 cm −1 and λ = −187cm −1, respectively.