The relation between the vacancy ordering and optical properties was investigated by calculating the photo-absorption spectra of 1Cd1Ga2Se4 with four kinds of vacancy configurations. It was shown that both the E1 and E2 transitions around 4 to 6eV showed optical anisotropy in the defect-chalcopyrite structure, while only the E2 energy region above 5eV showed a large anisotropy in the defect-stannite, pseudo-cubic, and its family structures. All these results were closely related to the vacancy ordering in 1Cd1Ga2Se4 compounds.

Vacancy-Order-Induced Optical Anisotropy in 1II1III2VI4 Compounds. M.Ishikawa, T.Nakayama: Physica Status Solidi B, 2002, 229[1], 297-300