van der Waals photothermoelectric effect in atomic layer heterojunctions

ORAL

Abstract

Two-dimensional (2D) van der Waals (vdW) heterostructures provide exceptional opportunities for new physics and devices due to their unprecedented ability to tune the electronic, optical, magnetic and spintronic properties by atomic layer stacking and electrostatic gating. Harnessing this versatility requires a fundamental understanding of light-matter interactions and establishing new functionalities for photon-charge and photon-spin conversions. Here, we report the first observation of a highly-tunable vdW photothermoelectric effect in dual-gated MoS2/graphene junctions with a striking multiple-polarity switching of photocurrent as a function of junction bias and carrier density. In stark contrast to photovoltaic effects arising from excitonic absorption in MoS2, the vdW photothermoelectric effect originates from photoexcitation of hot electrons in graphene and thermoelectric transport across the vdW junction. Systematic studies of photoconductance as a function of photon energy and intensity reveal vdW photothermoelectric effect as the dominant mechanism for photocurrent generation at room temperature, as opposed to excitonic absorption. These findings provide an important step for understanding and control of vdW-interface devices.

*NSF MRSEC DMR-1420451

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Presenters

  • Yunqiu (Kelly) Luo

    • Laboratory of Atomic and Solid State Physics (LASSP), Cornell University
    • Ohio State Univ - Columbus
    • Cornell University
    • Laboratory of Atomic and Solid State Physics, Cornell University

Authors

  • Yunqiu (Kelly) Luo

    • Laboratory of Atomic and Solid State Physics (LASSP), Cornell University
    • Ohio State Univ - Columbus
    • Cornell University
    • Laboratory of Atomic and Solid State Physics, Cornell University

  • Tong Zhou

    • Department of Physics, State Univ of NY - Buffalo
    • Department of Physics, State University at New York at Buffalo
    • Physics, University at Buffalo, State University of New York
    • State Univ of NY - Buffalo

  • Mahesh R Neupane

    • Sensors and Electron Devices Directorate, U.S. Army Research Laboratory
    • SEDD, US Army Rsch Lab - Adelphi

  • Alex Matos Abiague

    • Wayne State Univ
    • Department of Physics and Astronomy, Wayne State University
    • Wayne State University
    • Physics and Astronomy, Wayne State University

  • Ryan Bailey-Crandell

    • Physics, Ohio State University

  • Michael J Newburger

    • Physics, Ohio State University

  • Igor Lyalin

    • Physics, Ohio State University

  • Igor Zutic

    • Department of Physics, State Univ of NY - Buffalo
    • University at Buffalo
    • Physics, Buffalo State Univeristy of New York
    • Department of Physics, State University at New York at Buffalo
    • State Univ of NY - Buffalo
    • Physics, University at Buffalo, State University of New York
    • Department of Physics, University at Buffalo
    • Department of physics, University at Buffalo

  • Roland Kawakami

    • Ohio State Univ - Columbus
    • Department of Physics, The Ohio State University
    • Physics, Ohio State University