Strain-Induced Electronic Structure Changes in Stacked van der Waals Heterostructures

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• 作者：Yongmin He ; Yang Yang ; Zhuhua Zhang ; Yongji Gong ; Wu Zhou ; Zhili Hu ; Gonglan Ye ; Xiang Zhang ; Elisabeth Bianco ; Sidong Lei ; Zehua Jin ; Xiaolong Zou ; Yingchao Yang ; Yuan Zhang ; Erqing Xie ; Jun Lou ; Boris Yakobson ; Robert Vajtai ; Bo Li ; Pulickel Ajayan
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：May 11, 2016
• 年：2016
• 卷：16
• 期：5
• 页码：3314-3320
• 全文大小：493K
• 年卷期：0
• ISSN：1530-6992

文摘

Vertically stacked van der Waals heterostructures composed of compositionally different two-dimensional atomic layers give rise to interesting properties due to substantial interactions between the layers. However, these interactions can be easily obscured by the twisting of atomic layers or cross-contamination introduced by transfer processes, rendering their experimental demonstration challenging. Here, we explore the electronic structure and its strain dependence of stacked MoSe₂/WSe₂ heterostructures directly synthesized by chemical vapor deposition, which unambiguously reveal strong electronic coupling between the atomic layers. The direct and indirect band gaps (1.48 and 1.28 eV) of the heterostructures are measured to be lower than the band gaps of individual MoSe₂ (1.50 eV) and WSe₂ (1.60 eV) layers. Photoluminescence measurements further show that both the direct and indirect band gaps undergo redshifts with applied tensile strain to the heterostructures, with the change of the indirect gap being particularly more sensitive to strain. This demonstration of strain engineering in van der Waals heterostructures opens a new route toward fabricating flexible electronics.