应力调控单层MoSe2的光致发光光谱特性

Photoluminescence Spectrum of Monolayer MoSe 2 Tuned by Strain

为了探究二维材料在片上可调有源光学器件领域的应用潜力,通过干法转印将由机械剥离法得到的高品质单层二硒化钼转移到正面涂有150nm厚聚甲基丙烯酸甲酯的双轴压电陶瓷上,制作出可应力调控发光性质的单层二硒化钼光源.对双轴压电陶瓷施加驱动电压,使电信号转化为应力信号,观察低温下(~5K)二硒化钼光致发光光谱中本征激子态、带电激子态信号峰随应力变化的规律.结果表明:在应力由拉伸应力转变为压应力并逐渐增大的过程中,本征激子态、带电激子态信号峰分别出现了~3.8meV、~3.7meV的波长蓝移.增大压应力、拉伸应力都会导致本征激子态、带电激子态信号峰光强线性降低.同时,与泵浦光圆极化相关的圆偏振度也随应力变化表现出规律性改变.此项研究证明了应力调控与单层二硒化钼光学性质之间的紧密关系,为开发各类基于二维材料的片上可调有源光学器件提供支持.

In order to explore the potential of 2D materials in the application field of on-chip tunable active optical devices,a strain-tunable light source with monolayer MoSe 2 was produced.High quality monolayer MoSe 2 was obtained by micromechanical exfoliation method.The all-dry transfer method was used to transfer monolayer MoSe 2 to biaxial piezoelectric ceramics coated with 150 nm thick Polymethylmethacrylate.The electric field was applied to the biaxial piezoelectric ceramic,which converts the electrical signal into the strain signal,to controll the optical properties of MoSe 2.The variation of intrinsic exciton and charge exciton peaks of the MoSe 2 with strain tuning were observed from photoluminescence spectra at low temperature of^5 K.The results indicate that blueshifts of^3.8 meV and^3.7 meV appear in the intrinsic exciton and charge exciton peaks,respectively,when the strain is tuned from tension to compression.And increasing compressive strain or tensile strain will decrease the intensity of intrinsic exciton and charge exciton peak linearly.At the same time,the circular polarization degree of the emission related to the circular polarization of the pump laser also shows regular change with the variation of strain.This research confirms the close correlation between the stain tuning and the optical properties of monolayer MoSe 2.It provides support for the development of various on-chip tunable active optical devices based on 2D materials.