Absorption and photoluminescence studies of CdGa 2S 4:Cr

Abstract

The potential of using ternary defect chalcopyrites as laser active materials is investigated by performing absorption, photoluminescence, and EPR studies of as-grown and vacuum annealed Cr-doped CdGa 2S 4. Although no consistent affect of annealing is observed, an increased concentration of Cr in the melt during growth is shown to broaden an absorption band at 1288 nm. Several of the absorption bands could be attributed to multiple charge states of Cr thought to be present in the crystal. A broad fluorescence was observed at visible wavelengths; however, no emission was detected in the middle-infrared region, contrary to expectation. The lack of infrared fluorescence may be attributed to an exchange interaction involving Cr impurities.