Influence of Stoichiometry on the Optical and Electrical Properties of Chemical Vapor Deposition Derived MoS2

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• 作者：In Soo Kim ; Vinod K. Sangwan ; Deep Jariwala ; Joshua D. Wood ; Spencer Park ; Kan-Sheng Chen ; Fengyuan Shi ; Francisco Ruiz-Zepeda ; Arturo Ponce ; Miguel Jose-Yacaman ; Vinayak P. Dravid ; Tobin J. Marks ; Mark C. Hersam ; Lincoln J. Lauhon
• 刊名：ACS Nano
• 出版年：2014
• 出版时间：October 28, 2014
• 年：2014
• 卷：8
• 期：10
• 页码：10551-10558
• 全文大小：551K
• ISSN：1936-086X

文摘

Ultrathin transition metal dichalcogenides (TMDCs) of Mo and W show great potential for digital electronics and optoelectronic applications. Whereas early studies were limited to mechanically exfoliated flakes, the large-area synthesis of 2D TMDCs has now been realized by chemical vapor deposition (CVD) based on a sulfurization reaction. The optoelectronic properties of CVD grown monolayer MoS₂ have been intensively investigated, but the influence of stoichiometry on the electrical and optical properties has been largely overlooked. Here we systematically vary the stoichiometry of monolayer MoS₂ during CVD via controlled sulfurization and investigate the associated changes in photoluminescence and electrical properties. X-ray photoelectron spectroscopy is employed to measure relative variations in stoichiometry and the persistence of MoO_x species. As MoS2鈭捨?/sub> is reduced (increasing 未), the field-effect mobility of monolayer transistors increases while the photoluminescence yield becomes nonuniform. Devices fabricated from monolayers with the lowest sulfur content have negligible hysteresis and a threshold voltage of 鈭? V. We conclude that the electrical and optical properties of monolayer MoS₂ crystals can be tuned via stoichiometry engineering to meet the requirements of various applications.

Keywords:

transition metal dichalcogenides; molybdenum disulfide; chemical vapor deposition; stoichiometry; photoluminescence; field-effect mobility; X-ray photoelectron spectroscopy