On the impact of the stress situation on the optical properties of $WSe_2$ monolayers under high pressure

IF 1.2 Q3 PHYSICS, MULTIDISCIPLINARY

Papers in Physics Pub Date : 2019-06-21 DOI:10.4279/PIP.110005

A. Francisco-López, B. Han, D. Lagarde, X. Marie, B. Urbaszek, C. Robert, A. Goñi

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引用次数: 6

Abstract

We have studied the optical properties of $WSe_2$ monolayers (ML) by means of photoluminescence (PL), PL excitation (PLE) and Raman scattering spectroscopy at room temperature and as a function of hydrostatic pressure up to ca. 12 GPa. For comparison the study comprises two cases: A single $WSe_2$ ML directly transferred onto one of the diamonds of the diamond anvil cell and a $WSe_2$ ML encapsulated into hexagonal boron nitride (hBN) layers. The pressure dependence of the A and B exciton, as determined by PL and PLE, respectively, is very different for the case of the bare $WSe_2$ ML and the $hBN/WSe_2-ML/hBN$ heterostructure. Whereas for the latter the A and B exciton energy increases linearly with increasing pressure at a rate of 3.5 to 3.8 meV/GPa, for the bare $WSe_2$ ML the A and B exciton energy decreases with a coefficient of -3.1 and -1.3 meV/GPa, respectively. We interpret that this behavior is due to a different stress situation. For a single ML the stress tensor is essentially uniaxial with the compressive stress component in the direction perpendicular to the plane of the ML. In contrast, for the substantially thicker $hBN/WSe_2-ML/hBN$ heterostructure the compression is hydrostatic. The results from an analysis of the pressure dependence of the frequency of Raman active modes comply with the interpretation of having a different stress situation in each case. Reviewed by: A. San Miguel, Institut Lumière Matière, Université de Lyon, France; Edited by: J. S. Reparaz

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高压下应力状态对$WSe_2$单层光学性能的影响

利用光致发光(PL)、PL激发(PLE)和拉曼散射光谱，研究了WSe_2单层膜(ML)在室温下的光学性质和高达12 GPa的静水压力的函数关系。为了进行比较，本研究分为两种情况:一种是将单个$WSe_2$ ML直接转移到金刚石砧细胞中的一个金刚石上，另一种是将$WSe_2$ ML包裹在六方氮化硼(hBN)层中。在裸WSe_2-ML和hBN/WSe_2-ML/hBN异质结构中，分别用PL和PLE测定的A和B激子的压力依赖性是非常不同的。而对于后者，A和B激子能量随压力的增加而线性增加，速率为3.5 ~ 3.8 meV/GPa，而对于裸WSe_2 - ML, A和B激子能量分别以-3.1和-1.3 meV/GPa的系数下降。我们解释说，这种行为是由于不同的压力情况。对于单个ML，应力张量基本上是单轴的，压应力分量垂直于ML平面的方向。相反，对于较厚的$hBN/WSe_2-ML/hBN$异质结构，压缩是流体静力的。对拉曼主动模频率的压力依赖性分析结果符合每种情况下具有不同应力情况的解释。评审:A. San Miguel，法国里昂大学Institut lumi mati研究所;编辑:J. S. Reparaz

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来源期刊

Papers in Physics PHYSICS, MULTIDISCIPLINARY-

CiteScore

1.90

自引率

0.00%

发文量

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