The Study of Optical Properties of III2–VI3 Defect Semiconductor Group Compounds Ga2S3, Ga2Se3, In2S3, and In2Se3

Herein, high‐quality III2VI3 (III = Ga, In and VI = S, Se) single crystals are successfully grown by a chemical vapor transport method. X‐ray diffraction and Raman spectroscopy verify crystal structure, crystalline state, and vibration modes of the as‐grown III2VI3 crystals. According to the structure characterization, Ga2S3 is crystallized in a monoclinic structure, whereas Ga2Se3 belongs to the cubic zincblende phase. The crystal structure of In2S3 is tetragonal, whereas that of In2Se3 may come from a hexagonal layered structure. The four crystal structures are the most stable phases crystallized in Ga2S3, Ga2Se3, In2S3, and In2Se3, respectively. All the mostly stable phase in each of Ga2S3, Ga2Se3, In2S3, and In2Se3 is different and changing. This result identifies the crystalline nature of the III–VI group defect crystals. Modulated thermoreflectance (TR) and optical transmission measurements of the series III2VI3 compounds are, respectively, implemented. The results indicate that all defective Ga2S3, Ga2Se3, In2S3, and In2Se3 crystals are direct semiconductors. Photoluminescence of Ga2S3 and photoconductivity of the Ga2Se3, In2S3, and In2Se3 defect compounds are, respectively, carried out, and the experimental results are demonstrated and analyzed herein