title: Unusual Exciton-Phonon Interactions at van der Waals Engineered Interfaces.
abstract: 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 WSe2monolayer 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 WSe2directly or via an A1'optical phonon from WSe2. We further showed that the interfacial Raman scattering is distinct between hBN-encapsulated and hBN-sandwiched WSe2sample geometries. 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.affiliation: Department of Physics, University of Washington , Seattle, Washington 98195, United States.
authors.forename: Colin M
authors.identifier: 0000-0002-9551-8237
authors.initials: CM
authors.lastname: Chow
authors.affiliation: Department of Physics and Centre of Theoretical and Computational Physics, University of Hong Kong , Hong Kong, China.
authors.forename: Hongyi
authors.initials: H
authors.lastname: Yu
authors.affiliation: Department of Physics, University of Washington , Seattle, Washington 98195, United States.
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Jones
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Jiaqiang
authors.initials: J
authors.lastname: Yan
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.|Department of Materials Science and Engineering, University of Tennessee , Knoxville, Tennessee 37996, United States.
authors.forename: David G
authors.initials: DG
authors.lastname: Mandrus
authors.affiliation: Advanced Materials Laboratory, National Institute for Materials Science , Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Taniguchi
authors.affiliation: Advanced Materials Laboratory, National Institute for Materials Science , Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Kenji
authors.identifier: 0000-0003-3701-8119
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: Department of Physics and Centre of Theoretical and Computational Physics, University of Hong Kong , Hong Kong, China.
authors.forename: Wang
authors.initials: W
authors.lastname: Yao
authors.affiliation: Department of Physics, University of Washington , Seattle, Washington 98195, United States.|Department of Materials Science and Engineering, University of Washington , Seattle, Washington 98195, United States.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Xu
keywords: WSe2; exciton−phonon interaction; hexagonal boron nitride; van der Waals interface