Direct Measurement of the Tunable Electronic Structure of Bilayer MoS2 by Interlayer Twist

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• 作者：Po-Chun Yeh ; Wencan Jin ; Nader Zaki ; Jens Kunstmann ; Daniel Chenet ; Ghidewon Arefe ; Jerzy T. Sadowski ; Jerry I. Dadap ; Peter Sutter ; James Hone ; Richard M. Osgood Jr.
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：February 10, 2016
• 年：2016
• 卷：16
• 期：2
• 页码：953-959
• 全文大小：424K
• ISSN：1530-6992

文摘

Using angle-resolved photoemission on micrometer-scale sample areas, we directly measure the interlayer twist angle-dependent electronic band structure of bilayer molybdenum-disulfide (MoS₂). Our measurements, performed on arbitrarily stacked bilayer MoS₂ flakes prepared by chemical vapor deposition, provide direct evidence for a downshift of the quasiparticle energy of the valence band at the Brillouin zone center (Γ? point) with the interlayer twist angle, up to a maximum of 120 meV at a twist angle of ～40°. Our direct measurements of the valence band structure enable the extraction of the hole effective mass as a function of the interlayer twist angle. While our results at Γ? agree with recently published photoluminescence data, our measurements of the quasiparticle spectrum over the full 2D Brillouin zone reveal a richer and more complicated change in the electronic structure than previously theoretically predicted. The electronic structure measurements reported here, including the evolution of the effective mass with twist-angle, provide new insight into the physics of twisted transition-metal dichalcogenide bilayers and serve as a guide for the practical design of MoS₂ optoelectronic and spin-/valley-tronic devices.