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Crystal Growth and Characterization of Layered Chalcogenide Compound Semiconductors - Ching-Hwa Ho

National Taiwan University of Science and Technology


LPS – amphi moyen

Starting from the invention of graphene, two-dimensional (2D) material such as transition-metal dichalcogenides (TMDCs) like MX2 (M=Mo, W, Re et al. and X=S and Se) have obtained substantial interests on studying their optoelectronics, physical, chemical and energy related applications due to their specific 2D and semiconductor behaviors. Because of explicit and excellent properties on the mechanical, chemical, electrical and optical performances, the TMDCs can be used as mechanic lubricant, electrode of photoelectrochemical cells, hydrogenation and hydrodesulfurization catalysts, transistors and flexible electronic devices. Moreover, beyond the TMDCs, there are still some 2D layered chalcogenides of group III-VI (e.g. InSe, GaSe, etc.) and group IV-VI (e.g. GeS, GeSe, SnSe, etc.) got more interests. The direct bandgap character of InSe and GaSe rendering the materials can be fabrication in luminescent devices and photodetectors. The in-plane optical anisotropy of the IV-VI layered GeS also making its feasibility for application in polarized optical devices.

In this presentation, single crystals of chalcogenides of TMDCs (e.g. ReS2, ReSe2, WSe2), III-VI (e.g. InSe), and IV-VI compounds (e.g. GeS) were grown by chemical vapour transport (CVT) method using I2 or ICl3 as the transport agent. Detailed characterization of the layered single crystals was implemented using X-ray diffraction, Raman scattering, X-ray photoelectron spectroscopy, electrical carrier transport, transmittance, photoluminescence, and modulation spectroscopy, etc. The analyses of experimental results demonstrated high crystal quality and good crystallinity of the as-grown chalcogenides crystals. The probable applications of the layered chalcogenide crystals as the electronics or optoelectronics devices are also discussed herein.

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