中国物理B ›› 2016, Vol. 25 ›› Issue (7): 77802-077802.doi: 10.1088/1674-1056/25/7/077802

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Strain-modulated excitonic gaps in mono- and bi-layer MoSe2

Jianting Ji(籍建葶), Anmin Zhang(张安民), Tianlong Xia(夏天龙), Po Gao(高坡), Yinghao Jie(揭英昊), Qian Zhang(张倩), Qingming Zhang(张清明)   

  1. Department of Physics, Beijing Key Laboratory of Opto-Electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
  • 收稿日期:2016-02-16 修回日期:2016-03-20 出版日期:2016-07-05 发布日期:2016-07-05
  • 通讯作者: Qingming Zhang E-mail:qmzhang@ruc.edu.cn
  • 基金资助:

    Project supported by the National Basic Research Program of China (Grant No. 2012CB921701) and the National Natural Science Foundation of China (Grant Nos. 11474357 and 11004245). Qingming Zhang and Tianlong Xia were supported by the Fundamental Research Funds for the Central Universities of China and the Research Funds of Renmin University of China.

Strain-modulated excitonic gaps in mono- and bi-layer MoSe2

Jianting Ji(籍建葶), Anmin Zhang(张安民), Tianlong Xia(夏天龙), Po Gao(高坡), Yinghao Jie(揭英昊), Qian Zhang(张倩), Qingming Zhang(张清明)   

  1. Department of Physics, Beijing Key Laboratory of Opto-Electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
  • Received:2016-02-16 Revised:2016-03-20 Online:2016-07-05 Published:2016-07-05
  • Contact: Qingming Zhang E-mail:qmzhang@ruc.edu.cn
  • Supported by:

    Project supported by the National Basic Research Program of China (Grant No. 2012CB921701) and the National Natural Science Foundation of China (Grant Nos. 11474357 and 11004245). Qingming Zhang and Tianlong Xia were supported by the Fundamental Research Funds for the Central Universities of China and the Research Funds of Renmin University of China.

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摘要：

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 meV) 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.

关键词: photoluminescence, strain, low-dimensional semiconductors

Abstract:

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 meV) 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.

Key words: photoluminescence, strain, low-dimensional semiconductors

中图分类号:  (Photoluminescence, properties and materials)

  • 78.55.-m
78.30.-j (Infrared and Raman spectra) 63.22.Np (Layered systems)