OPTICAL-PROPERTIES OF CD1-XCOXIN2SE4 SINGLE-CRYSTALS

Cd1-xCoxIn2Se4 (x = 0.0, 0.01, 0.05, 0.10, 0.50) single crystals were grown by the vertical Bridgman technique. The grown single crystals ha ve a pseudocubic structure. The optical energy gap of these single cry stals has an indirect energy gap whereas its value is decreased with i ncreases in composition x. The optical absorption peaks due to cobalt atoms are observed at each composition. It is suggested that the subst ituted cobalt atoms for cadmium atoms are located at T(d) symmetry of the CdIn2Se4 host lattice as Co2+ ions by the static crystal field the ory. These peaks can be attributed to the electronic transitions betwe en the split electron energy levels of Co2+ ions.