Light Emission Properties and Carrier Dynamics with Sturctural Evolution of Multilayer GaTe1-xSex (0≦x≦1)

Luthviyah Choirotul Muhimmah^1*, Yu-Hong Peng¹, Feng-Han Yu¹, Ching-Hwa Ho¹

¹Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, Taiwan

* Presenter:Luthviyah Choirotul Muhimmah, email:D10822801@mail.ntust.edu.tw

Two-dimensional (2D) layered gallium monochalcogenide (GaX, X=S, Se, Te) semiconductor crystals possess great promise for potential electronic and photonic applications. In this work, the structure and properties of full series few-layer GaTe1-xSex with selenium composition are examined. The dominant monoclinic structure is obtained for x≤0.4, and the dominant hexagonal structure is obtained for x≥0.5. The mixed-phase of GaTe1-xSex is verified by high-resolution transmission electron microscopy (HRTEM). Micro-photoluminescence measurement indicates the bandgap of the monoclinic phase increases with selenium content from 1.652 eV (M-GaTe) to 1.779 eV (M-GaTe0.6Se0.4), while the hexagonal phase bandgap decreases from 1.998 eV (H-GaSe) to 1.588 eV (H-GaTe). Micro-time-resolved photoluminescence (μTRPL) and area fluorecence lifetime mapping (AFLM) of the few-layer GaTe1-xSex indicates that the luminescence decay time constant increases with the selenium content and mixed crystals GaTe1-xSex (0≤x≤0.4), the decay time constant of the monoclinic phase is faster than the hexagonal phase in all compositions. Carrier transport and photoconduction behaviors have been evaluated using photo-current measurement. The superior light-emission and photo-detection capability of the GaTe1-xSex layers (0≤x≤1) renders them available for further optoelectronic devices applications.

Keywords: 2D semiconductor, Photoluminescence, Decay Time Constant, Carrier Transport, Optoelectronics