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Title: Unusual exciton–phonon interactions at van der Waals engineered interfaces

Raman scattering is a ubiquitous phenomenon in light–matter interactions, which reveals a material’s electronic, structural, and thermal properties. Controlling this process would enable new ways of studying and manipulating fundamental material properties. Here, we report a novel Raman scattering process at the interface between different van der Waals (vdW) materials as well as between a monolayer semiconductor and 3D crystalline substrates. We find that interfacing a WSe 2 monolayer with materials such as SiO 2, sapphire, and hexagonal boron nitride (hBN) enables Raman transitions with phonons that are either traditionally inactive or weak. This Raman scattering can be amplified by nearly 2 orders of magnitude when a foreign phonon mode is resonantly coupled to the A exciton in WSe 2 directly or via an A 1' optical phonon from WSe 2. We further showed that the interfacial Raman scattering is distinct between hBN-encapsulated and hBN-sandwiched WSe 2 sample geometries. Finally, this cross-platform electron–phonon coupling, as well as the sensitivity of 2D excitons to their phononic environments, will prove important in the understanding and engineering of optoelectronic devices based on vdW heterostructures.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [3] ;  [4] ;  [5] ;  [5] ;  [2] ;  [1]
  1. Univ. of Washington, Seattle, WA (United States)
  2. Univ. of Hong Kong, Hong Kong (China)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. (United States)
  5. National Institute for Materials Science, Ibaraki (Japan)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 17; Journal Issue: 2; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; exciton−phonon interaction; hexagonal boron nitride; van der Waals interface; WSe2
OSTI Identifier:
1350949

Chow, Colin M., Yu, Hongyi, Jones, Aaron M., Yan, Jiaqiang, Mandrus, David G., Univ. of Tennessee, Knoxville, TN, Taniguchi, Takashi, Watanabe, Kenji, Yao, Wang, and Xu, Xiaodong. Unusual exciton–phonon interactions at van der Waals engineered interfaces. United States: N. p., Web. doi:10.1021/acs.nanolett.6b04944.
Chow, Colin M., Yu, Hongyi, Jones, Aaron M., Yan, Jiaqiang, Mandrus, David G., Univ. of Tennessee, Knoxville, TN, Taniguchi, Takashi, Watanabe, Kenji, Yao, Wang, & Xu, Xiaodong. Unusual exciton–phonon interactions at van der Waals engineered interfaces. United States. doi:10.1021/acs.nanolett.6b04944.
Chow, Colin M., Yu, Hongyi, Jones, Aaron M., Yan, Jiaqiang, Mandrus, David G., Univ. of Tennessee, Knoxville, TN, Taniguchi, Takashi, Watanabe, Kenji, Yao, Wang, and Xu, Xiaodong. 2017. "Unusual exciton–phonon interactions at van der Waals engineered interfaces". United States. doi:10.1021/acs.nanolett.6b04944. https://www.osti.gov/servlets/purl/1350949.
@article{osti_1350949,
title = {Unusual exciton–phonon interactions at van der Waals engineered interfaces},
author = {Chow, Colin M. and Yu, Hongyi and Jones, Aaron M. and Yan, Jiaqiang and Mandrus, David G. and Univ. of Tennessee, Knoxville, TN and Taniguchi, Takashi and Watanabe, Kenji and Yao, Wang and Xu, Xiaodong},
abstractNote = {Raman scattering is a ubiquitous phenomenon in light–matter interactions, which reveals a material’s electronic, structural, and thermal properties. Controlling this process would enable new ways of studying and manipulating fundamental material properties. Here, we report a novel Raman scattering process at the interface between different van der Waals (vdW) materials as well as between a monolayer semiconductor and 3D crystalline substrates. We find that interfacing a WSe2 monolayer with materials such as SiO2, sapphire, and hexagonal boron nitride (hBN) enables Raman transitions with phonons that are either traditionally inactive or weak. This Raman scattering can be amplified by nearly 2 orders of magnitude when a foreign phonon mode is resonantly coupled to the A exciton in WSe2 directly or via an A1' optical phonon from WSe2. We further showed that the interfacial Raman scattering is distinct between hBN-encapsulated and hBN-sandwiched WSe2 sample geometries. Finally, this cross-platform electron–phonon coupling, as well as the sensitivity of 2D excitons to their phononic environments, will prove important in the understanding and engineering of optoelectronic devices based on vdW heterostructures.},
doi = {10.1021/acs.nanolett.6b04944},
journal = {Nano Letters},
number = 2,
volume = 17,
place = {United States},
year = {2017},
month = {1}
}