High Quality Factor Mechanical Resonators Based on WSe2 Monolayers

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• 作者：Nicolas Morell ; Antoine Reserbat-Plantey ; Ioannis Tsioutsios ; Kevin G. Schädler ; François Dubin ; Frank H. L. Koppens ; Adrian Bachtold
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：August 10, 2016
• 年：2016
• 卷：16
• 期：8
• 页码：5102-5108
• 全文大小：479K
• 年卷期：0
• ISSN：1530-6992

文摘

Suspended monolayer transition metal dichalcogenides (TMD) are membranes that combine ultralow mass and exceptional optical properties, making them intriguing materials for opto-mechanical applications. However, the low measured quality factor of TMD resonators has been a roadblock so far. Here, we report an ultrasensitive optical readout of monolayer TMD resonators that allows us to reveal their mechanical properties at cryogenic temperatures. We find that the quality factor of monolayer WSe₂ resonators greatly increases below room temperature, reaching values as high as 1.6 × 10⁴ at liquid nitrogen temperature and 4.7 × 10⁴ at liquid helium temperature. This surpasses the quality factor of monolayer graphene resonators with similar surface areas. Upon cooling the resonator, the resonant frequency increases significantly due to the thermal contraction of the WSe₂ lattice. These measurements allow us to experimentally study the thermal expansion coefficient of WSe₂ monolayers for the first time. High Q-factors are also found in resonators based on MoS₂ and MoSe₂ monolayers. The high quality-factor found in this work opens new possibilities for coupling mechanical vibrational states to two-dimensional excitons, valley pseudospins, and single quantum emitters and for quantum opto-mechanical experiments based on the Casimir interaction.