Chloride-Driven Chemical Vapor Transport Method for Crystal Growth of Transition Metal Dichalcogenides

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• 作者：Alberto Ubaldini ; Jacim Jacimovic ; Nicolas Ubrig ; Enrico Giannini
• 刊名：Crystal Growth & Design
• 出版年：2013
• 出版时间：October 2, 2013
• 年：2013
• 卷：13
• 期：10
• 页码：4453-4459
• 全文大小：386K
• 年卷期：v.13,no.10(October 2, 2013)
• ISSN：1528-7505

文摘

Single crystals of Mo and Ta dichalcogenides, MX₂ (M = Mo, Ta and X = S, Se, Te), have been grown by the vapor transport method in closed atmosphere, using a novel transport reaction that involves a mixture of M, MCl₅ and X as a source. The most important parameters that must be kept under control for succeeding in crystal growth are the temperature, which depends mainly on X, and the initial M:MCl₅ ratio. The best growth temperature is found to be the highest in the case of tellurides, the lowest in the case of sulfides and intermediate for the selenides. The optimal M:MCl₅ molar ratio decreases with the atomic number of the chalcogen, ranging from 50 for sulfides to 15 for tellurides. Values out of this range made it not possible to control the nucleation process. The high quality of the crystals grown by using this method is confirmed by X-ray diffraction studies, Raman spectroscopy and electrical resistivity measurements, and proved to be higher than that of commercially available MoS₂ crystals. In the case of TaS₂ and TaSe₂, using a high starting chloride fraction and a low reaction temperature, the growth of thin (渭m) and long (mm) whiskers is observed. An explanation of their growth mechanism is proposed.