Optical characterization of ZnO/ZnS mixed semiconductor as the color palette solid-state lighting device
林旻翰1*, 李嘉軒1, 陳雅涵1, 莊慶安1, 何清華1
1應用科技研究所, 國立台灣科技大學, 台北市, Taiwan
* presenting author:Man-Han Lin, email:D10222604@mail.ntust.edu.tw
The ZnO/ZnS crystals are well-known II-VI compound with wide band gap available for energy and optoelectronics use due to their defect and optical characteristic for technological application. In this work, ZnO/ZnS single crystals were successfully grown by chemical vapor transport method using iodine (I₂) as the transport agent. The as-grown ZnO/ZnS crystals essentially show transparent and light yellow. X-ray diffraction measurements of the materials showed cubic of ZnO/ZnS for the as-grown crystals. The optical band edge of ZnO/ZnS were characterized by photoluminescence and thermoreflectance measurements. The optical band gaps were determined to be 3.3 eV for ZnO and 3.8 eV for ZnS respectively. The luminescence spectroscopy of both defect and surface states of ZnO/ZnS were obtained via photoluminescence experiments. The defect luminescence of oxygen vacancy (Vο in ZnO) and sulfur vacancy (Vs in ZnS) are those of visible cyan green and violet lights. We propose that white light could be formed by using of defect state emissions of the mixing ZnO/ZnS compound, and which renders the materials could be applied in solid-state lighting.

Keywords: Thermoreflectance, Solid-state lighting, Photoluminescence, Single crystals, II-VI compound semiconductor