Luthviyah Choirotul Muhimmah1*, Mei-Chan Chiou1, Ching-An Chuang1, Ching-Hwa Ho1
1Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, 106, Taiwan
* Presenter:Luthviyah Choirotul Muhimmah,
The III-VI layered semiconductors has interesting properties for future optoelectronic applications. Among the III-VI layered semiconductor, Gallium telluride (GaTe) has a monoclinic structure, p-type semiconductor, and a direct bandgap at 1.65 eV at room temperature. GaTe doped with Se (GaTe1-xSex) (x = 0, 0.1, 0.2, 0.4, 0.5, 1) were grown by chemical vapor transport with iodine (I2) as its transport agent. Here, we report the structure changing from monoclinic GaTe to hexagonal GaSe while the increasing of Se composition. The lattice constant and composition of GaTe1-xSex were confirmed by X-ray Diffraction (XRD) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS). The monoclinic structures were obtained for x≤0.4 and the hexagonal structures were obtained for x≥0.5. Raman spectroscopy was carried out to explore the composition-dependent vibration frequency of phonons. It was observed that the increasing Se (x) composition from 0 to 1, the Raman frequency of the Ag (the peak as a function of Te composition) decreased monotonically from 123 cm-1 (GaTe) to 118 cm-1 (GaTe0.5Se0.5).We also investigate photon energy transition of photoluminescence few-layer GaTe1-xSexalloys (x = 0, 0.1, 0.2, 0.4, 0.5, 1). The photon energy increases linearly with Se composition (x = 0, 0.1, 0.2, 0.4) form 1.65 eV (GaTe) to 1,725 eV, while for x = 0.5 decreases from 2 eV (GaSe) to 1.54 eV. The photoluminescence in GaTe1-xSex crystals has been investigated as a function of temperature and angle-dependent. Based on temperature-dependent photoluminescence, the photon energy shifted to a higher position from room temperature (300K) to low temperature (20K). Due to the difference polarized orientation, Eb has a higher photon energy than E//b.

Keywords: Crystal growth, Gallium telluride selenide, Photoluminescence, Crystal structure