Strain-modulated excitonic gaps in mono-and bi-layer MoSe_2

Photoluminescence（PL） and Raman spectra under uniaxial strain were measured in mono- and bi-layer MoSe2 to comparatively investigate the evolution of excitonic gaps and Raman phonons with strain. We observed that the strain dependence of excitonic gaps shows a nearly linear behavior in both flakes....

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Bibliographic Details
Published in中国物理B：英文版 no. 7; pp. 455 - 458
Main Author 籍建葶 张安民 夏天龙 高坡 揭英昊 张倩 张清明
Format Journal Article
LanguageEnglish
Published 2016
Subjects
D轨道
光致发光
单层
应变控制
应变测量
拉曼光谱
激子
调制
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Summary:Photoluminescence（PL） and Raman spectra under uniaxial strain were measured in mono- and bi-layer MoSe2 to comparatively investigate the evolution of excitonic gaps and Raman phonons with strain. We observed that the strain dependence of excitonic gaps shows a nearly linear behavior in both flakes. One percent of strain increase gives a reduction of 42 meV（35 me V） in A-exciton gap in monolayer（bilayer） MoSe2. The PL width remains little changed in monolayer MoSe2 while it increases rapidly with strain in the bilayer case. We have made detailed discussions on the observed strain-modulated results and compared the difference between monolayer and bilayer cases. The hybridization between 4d orbits of Mo and 4p orbits of Se, which is controlled by the Se–Mo–Se bond angle under strain, can be employed to consistently explain the observations. The study may shed light into exciton physics in few-layer MoSe2 and provides a basis for their applications.
Bibliography:Photoluminescence（PL） and Raman spectra under uniaxial strain were measured in mono- and bi-layer MoSe2 to comparatively investigate the evolution of excitonic gaps and Raman phonons with strain. We observed that the strain dependence of excitonic gaps shows a nearly linear behavior in both flakes. One percent of strain increase gives a reduction of 42 meV（35 me V） in A-exciton gap in monolayer（bilayer） MoSe2. The PL width remains little changed in monolayer MoSe2 while it increases rapidly with strain in the bilayer case. We have made detailed discussions on the observed strain-modulated results and compared the difference between monolayer and bilayer cases. The hybridization between 4d orbits of Mo and 4p orbits of Se, which is controlled by the Se–Mo–Se bond angle under strain, can be employed to consistently explain the observations. The study may shed light into exciton physics in few-layer MoSe2 and provides a basis for their applications.
11-5639/O4
photoluminescence strain low-dimensional semiconductors
ISSN:1674-1056
2058-3834