Two-Step Growth of Two-Dimensional WSe2/MoSe2 Heterostructures

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• 作者：Yongji Gong ; Sidong Lei ; Gonglan Ye ; Bo Li ; Yongmin He ; Kunttal Keyshar ; Xiang Zhang ; Qizhong Wang ; Jun Lou ; Zheng Liu ; Robert Vajtai ; Wu Zhou ; Pulickel M. Ajayan
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：September 9, 2015
• 年：2015
• 卷：15
• 期：9
• 页码：6135-6141
• 全文大小：493K
• ISSN：1530-6992

文摘

Two dimensional (2D) materials have attracted great attention due to their unique properties and atomic thickness. Although various 2D materials have been successfully synthesized with different optical and electrical properties, a strategy for fabricating 2D heterostructures must be developed in order to construct more complicated devices for practical applications. Here we demonstrate for the first time a two-step chemical vapor deposition (CVD) method for growing transition-metal dichalcogenide (TMD) heterostructures, where MoSe₂ was synthesized first and followed by an epitaxial growth of WSe₂ on the edge and on the top surface of MoSe₂. Compared to previously reported one-step growth methods, this two-step growth has the capability of spatial and size control of each 2D component, leading to much larger (up to 169 渭m) heterostructure size, and cross-contamination can be effectively minimized. Furthermore, this two-step growth produces well-defined 2H and 3R stacking in the WSe₂/MoSe₂ bilayer regions and much sharper in-plane interfaces than the previously reported MoSe₂/WSe₂ heterojunctions obtained from one-step growth methods. The resultant heterostructures with WSe₂/MoSe₂ bilayer and the exposed MoSe₂ monolayer display rectification characteristics of a p鈥搉 junction, as revealed by optoelectronic tests, and an internal quantum efficiency of 91% when functioning as a photodetector. A photovoltaic effect without any external gates was observed, showing incident photon to converted electron (IPCE) efficiencies of approximately 0.12%, providing application potential in electronics and energy harvesting.