Atomically Thin Heterostructures Based on Single-Layer Tungsten Diselenide and Graphene

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• 作者：Yu-Chuan Lin ; Chih-Yuan S. Chang ; Ram Krishna Ghosh ; Jie Li ; Hui Zhu ; Rafik Addou ; Bogdan Diaconescu ; Taisuke Ohta ; Xin Peng ; Ning Lu ; Moon J. Kim ; Jeremy T. Robinson ; Robert M Wallace ; Theresa S. Mayer ; Suman Datta ; Lain-Jong Li ; Joshua A. Robinson
• 刊名：Nano Letters
• 出版年：2014
• 出版时间：December 10, 2014
• 年：2014
• 卷：14
• 期：12
• 页码：6936-6941
• 全文大小：438K
• ISSN：1530-6992

文摘

Heterogeneous engineering of two-dimensional layered materials, including metallic graphene and semiconducting transition metal dichalcogenides, presents an exciting opportunity to produce highly tunable electronic and optoelectronic systems. In order to engineer pristine layers and their interfaces, epitaxial growth of such heterostructures is required. We report the direct growth of crystalline, monolayer tungsten diselenide (WSe₂) on epitaxial graphene (EG) grown from silicon carbide. Raman spectroscopy, photoluminescence, and scanning tunneling microscopy confirm high-quality WSe₂ monolayers, whereas transmission electron microscopy shows an atomically sharp interface, and low energy electron diffraction confirms near perfect orientation between WSe₂ and EG. Vertical transport measurements across the WSe₂/EG heterostructure provides evidence that an additional barrier to carrier transport beyond the expected WSe₂/EG band offset exists due to the interlayer gap, which is supported by theoretical local density of states (LDOS) calculations using self-consistent density functional theory (DFT) and nonequilibrium Green鈥檚 function (NEGF).

Keywords:

direct growth; heterostructures; graphene; tungsten diselenide (WSe₂); LEED/LEEM; electron tunneling; conductive AFM