The Study of Optical Properties of III<sub>2</sub>–VI<sub>3</sub> Defect Semiconductor Group Compounds Ga<sub>2</sub>S<sub>3</sub>, Ga<sub>2</sub>Se<sub>3</sub>, In<sub>2</sub>S<sub>3</sub>, and In<sub>2</sub>Se<sub>3</sub>
Ching‐Hwa Ho, Xiang-Ru Lai, Ching‐An Chuang, Wei-Li Kuo, K. K. Tiong
Abstract
Herein, high‐quality III 2 VI 3 (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 III 2 VI 3 crystals. According to the structure characterization, Ga 2 S 3 is crystallized in a monoclinic structure, whereas Ga 2 Se 3 belongs to the cubic zincblende phase. The crystal structure of In 2 S 3 is tetragonal, whereas that of In 2 Se 3 may come from a hexagonal layered structure. The four crystal structures are the most stable phases crystallized in Ga 2 S 3 , Ga 2 Se 3 , In 2 S 3 , and In 2 Se 3 , respectively. All the mostly stable phase in each of Ga 2 S 3 , Ga 2 Se 3 , In 2 S 3 , and In 2 Se 3 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 III 2 VI 3 compounds are, respectively, implemented. The results indicate that all defective Ga 2 S 3 , Ga 2 Se 3 , In 2 S 3 , and In 2 Se 3 crystals are direct semiconductors. Photoluminescence of Ga 2 S 3 and photoconductivity of the Ga 2 Se 3 , In 2 S 3 , and In 2 Se 3 defect compounds are, respectively, carried out, and the experimental results are demonstrated and analyzed herein.