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Study on Structures and Photoluminescence Emission of ZnS Microcrystals Grown by Thermal Deposition

In this work, we report on the controlled synthesis of ZnS microstructures with high purity on Au-coated silicon substrates by thermal evaporation of ZnS powder in Ar gas ambient at atmospheric pressure. The growth mechanism is confirmed as a typical vapor–liquid–solid (VLS) process. The prepared ZnS microstructures have wurtzite (hexagonal) structures. The catalytically grown ZnS microstructures, including microwires and microbelts, are tens of micrometers in length. | VNU Journal of Science: Mathematics – Physics, Vol. 33, No. 3 (2017) 60-67 Study on Structures and Photoluminescence Emission of ZnS Microcrystals Grown by Thermal Deposition Nguyen Van Nghia1,2,*, Pham Thanh Huy1, Le Van Vu3, Nguyen Duy Hung1 1 Advanced Institute of Science and Technology (AIST), Hanoi University of Science and Technology (HUST), 01 Dai Co Viet, Hanoi, Vietnam 2 Thuy Loi University, 175 Tay Son, Dong Da, Hanoi, Vietnam 3 Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Hanoi, Vietnam Received 08 June 2017 Revised 30 August 2017; Accepted 15 September 2017 Abstract: In this work, we report on the controlled synthesis of ZnS microstructures with high purity on Au-coated silicon substrates by thermal evaporation of ZnS powder in Ar gas ambient at atmospheric pressure. The growth mechanism is confirmed as a typical vapor–liquid–solid (VLS) process. The prepared ZnS microstructures have wurtzite (hexagonal) structures. The catalytically grown ZnS microstructures, including microwires and microbelts, are tens of micrometers in length. Energy-Dispersive X-Ray Spectroscopy EDS shows that the oxygen composition in the microstructures is trivial. The photoluminescence spectrum reveals strong ultraviolet emission and no other emission at room temperature also demonstrates that the ZnS microstructures are of high crystalline perfection. Optical transition from free exciton A, free exciton B are observed and analyzed through power-dependent at 10 K and temperature-dependent photoluminescence spectroscopy measurements are performed from 10 to 300 K. Our results indicate that ZnS microstructures grown by thermal evaporation, suggesting a great promise for high-efficiency light-emitting devices and lasers in the UV region. Keywords: ZnS, microwires, microbelts, photoluminescence. 1. Introduction Wide band-gap semiconducting nanowires and microwires have attracted considerable attention recently because of their promising applications in .