Out-of-plane electromechanical coupling in transition metal dichalcogenides
Out-of-plane electromechanical coupling in transition metal dichalcogenides
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DOI：
10.1063/1.5134091
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发表时间：
2020-02-03
影响因子：
4
通讯作者：
Yu, Edward T.
中科院分区：
文献类型：
--
作者：
Brennan, Christopher J.;Koul, Kalhan;Yu, Edward T.
单层过渡金属二硫属化物（TMD）在其原子平面内具有固有的压电性，但由于晶体结构的对称性，不应发生平面外的压电响应。然而，最近，MoS2显示出与挠曲电效应一致的平面外机电耦合。在这项研究中，MoSe2，WS2和WSe2的调查，以确定在其他单层TMD半导体材料的面外机电耦合的存在和强度。Piezoresponse力显微镜测量结果表明，单层二硫化钼，MoSe 2，WS2，和WSe 2都表现出平面外的机电响应。它们的平面外机电耦合的相对大小进行计算和相互比较，并从一个简单的模型flexoelectricity的预测。这个简单的模型正确地预测了这些材料的平面外机电响应的大小，并且测量值为更详细地了解单层TMD中的挠曲电响应以及评估其在包含这些材料的设备中的后果提供了有用的指导。
Monolayer transition metal dichalcogenides (TMDs) are intrinsically piezoelectric within the plane of their atoms, but out-of-plane piezoelectric response should not occur due to the symmetry of the crystal structure. Recently, however, MoS2 was shown to exhibit out-of-plane electromechanical coupling consistent with the flexoelectric effect. In this study, MoSe2, WS2, and WSe2 are investigated to determine the existence and strength of out-of-plane electromechanical coupling in other monolayer TMD semiconductor materials. Piezoresponse force microscopy measurements show that monolayer MoS2, MoSe2, WS2, and WSe2 all exhibit out-of-plane electromechanical response. The relative magnitudes of their out-of-plane electromechanical couplings are calculated and compared with one another and to predictions made from a simple model of flexoelectricity. This simple model correctly predicts the magnitude of out-of-plane electromechanical response in these materials, and the measured values provide useful guidance for both more detailed understanding of flexoelectric response in monolayer TMDs, and assessment of their consequences in devices incorporating these materials.