| Autor: |
Hesp NCH; ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Av. Carl Friedrich Gauss 3, 08860 Castelldefels, Barcelona, Spain., Svendsen MK; CAMD, Computational Atomic-Scale Materials Design, Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark., Watanabe K; Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan., Taniguchi T; International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan., Thygesen KS; CAMD, Computational Atomic-Scale Materials Design, Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark.; Center for Nanostructured Graphene (CNG), Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark., Torre I; ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Av. Carl Friedrich Gauss 3, 08860 Castelldefels, Barcelona, Spain., Koppens FHL; ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Av. Carl Friedrich Gauss 3, 08860 Castelldefels, Barcelona, Spain.; ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain. |
| Abstrakt: |
Independent control of carrier density and out-of-plane displacement field is essential for accessing novel phenomena in two-dimensional (2D) material heterostructures. While this is achieved with independent top and bottom metallic gate electrodes in transport experiments, it remains a challenge for near-field optical studies as the top electrode interferes with the optical path. Here, we characterize the requirements for a material to be used as the top-gate electrode and demonstrate experimentally that few-layer WSe 2 can be used as a transparent, ambipolar top-gate electrode in infrared near-field microscopy. We carry out nanoimaging of plasmons in a bilayer graphene heterostructure tuning the plasmon wavelength using a trilayer WSe 2 gate, achieving a density modulation amplitude exceeding 2 × 10 12 cm -2 . The observed ambipolar gate-voltage response allows us to extract the energy gap of WSe 2 , yielding a value of 1.05 eV. Our results provide an additional tuning knob to cryogenic near-field experiments on emerging phenomena in 2D materials and moiré heterostructures. |
