title: Vibrational Properties of h-BN and h-BN-Graphene Heterostructures Probed by Inelastic Electron Tunneling Spectroscopy.
abstract: Inelastic electron tunneling spectroscopy is a powerful technique for investigating lattice dynamics of nanoscale systems including graphene and small molecules, but establishing a stable tunnel junction is considered as a major hurdle in expanding the scope of tunneling experiments. Hexagonal boron nitride is a pivotal component in two-dimensional Van der Waals heterostructures as a high-quality insulating material due to its large energy gap and chemical-mechanical stability. Here we present planar graphene/h-BN-heterostructure tunneling devices utilizing thin h-BN as a tunneling insulator. With much improved h-BN-tunneling-junction stability, we are able to probe all possible phonon modes of h-BN and graphite/graphene at Γ and K high symmetry points by inelastic tunneling spectroscopy. Additionally, we observe that low-frequency out-of-plane vibrations of h-BN and graphene lattices are significantly modified at heterostructure interfaces. Equipped with an external back gate, we can also detect high-order coupling phenomena between phonons and plasmons, demonstrating that h-BN-based tunneling device is a wonderful playground for investigating electron-phonon couplings in low-dimensional systems.
authors.affiliation: Korea Research Institute of Standards and Science, Daejeon 305-340, Korea.
authors.forename: Suyong
authors.initials: S
authors.lastname: Jung
authors.affiliation: Korea Research Institute of Standards and Science, Daejeon 305-340, Korea.|University of Science and Technology, Daejeon 305-350, Korea.
authors.forename: Minkyu
authors.initials: M
authors.lastname: Park
authors.affiliation: Korea Research Institute of Standards and Science, Daejeon 305-340, Korea.
authors.forename: Jaesung
authors.initials: J
authors.lastname: Park
authors.affiliation: Korea Research Institute of Standards and Science, Daejeon 305-340, Korea.|Department of Physics, ChungNam National University, Daejeon 305-764, Korea.
authors.forename: Tae-Young
authors.initials: TY
authors.lastname: Jeong
authors.affiliation: Korea Research Institute of Standards and Science, Daejeon 305-340, Korea.|Department of Physics, Yonsei University, Seoul 120-749, Korea.
authors.forename: Ho-Jong
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Taniguchi
authors.affiliation: Korea Research Institute of Standards and Science, Daejeon 305-340, Korea.|University of Science and Technology, Daejeon 305-350, Korea.
authors.forename: Dong Han
authors.initials: DH
authors.lastname: Ha
authors.affiliation: Korea Research Institute of Standards and Science, Daejeon 305-340, Korea.
authors.forename: Chanyong
authors.initials: C
authors.lastname: Hwang
authors.affiliation: Korea Research Institute of Standards and Science, Daejeon 305-340, Korea.|University of Science and Technology, Daejeon 305-350, Korea.
authors.forename: Yong-Sung
authors.initials: YS
authors.lastname: Kim