Charge transfer in a transition metal dichalcogenide semiconductor/Weyl semimetal van der Waals junctions

ORAL

Abstract

Transient metal dichalcogenides (TMDs) heterostructures have recently made a meteoric rise in quantum device engineering due to its van der Waals (vdW) layered nature. A Weyl semimetal WTe2, also a TMD compound, displays a wide range of exotic electronic and spintronic properties. A central approach in heterostructures is driving charge transfer across the interface mainly governing the carrier dynamics, which determines fundamental optoelectronic properties. Here, we report a new type of CVD grown TMD vdW junctions with a semiconducting 2H-MoTe2 and its sister compound of semimetallic Td-WTe2. Time-resolved terahertz spectroscopy reveals the ultrafast relaxation of the photo-excited carriers in the junctions, which attributes to the charge transfer and the interlayer exciton decay serving as a fast relaxation channel with a characteristic time of ~0.6 ps, faster than that of the each layer (~1.5 ps from Td-WTe2 and ~5.9 ps from 2H-MoTe2). Moreover, we observe the negligible band-filling and hot-phonon effects according to the optical fluence (< 10 mJ/cm2) due to such an ultrafast interfacial relaxation channel. This ultrafast photoresponse in sister-compound large-area TMDs vdW junctions provide a platform for high-speed optoelectronic devices.

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Presenters

  • Kyusup Lee

    • Department of Electrical and Computer Engineering, National University of Singapore

Authors

  • Kyusup Lee

    • Department of Electrical and Computer Engineering, National University of Singapore

  • Jie Li

    • School of Materials Science and Engineering, Huazhong University of Science and Technology

  • Liang Cheng

    • School of Physical and Mathematical Sciences, Nanyang Technological University

  • Junyong Wang

    • Department of Physics, National University of Singapore

  • Dushyant Kumar

    • Department of Electrical and Computer Engineering, National University of Singapore

  • Qisheng Wang

    • Department of Electrical and Computer Engineering, and NUSNNI-NanoCore, National University of Singapore
    • Department of Electrical and Computer Engineering, National University of Singapore

  • Mengji Chen

    • Department of Electrical and Computer Engineering, National University of Singapore

  • Yang Wu

    • Department of Electrical and Computer Engineering, National University of Singapore

  • Goki Eda

    • Centre for Advanced 2D Materials, National University of Singapore
    • Department of Physics, National University of Singapore

  • Ee Min Chia

    • Nanyang Technological University
    • Department of Physics and Applied Physics, Nanyang Technological University
    • Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore
    • School of Physical and Mathematical Sciences, Nanyang Technological University

  • Haixin Chang

    • School of Materials Science and Engineering, Huazhong University of Science and Technology

  • Hyunsoo Yang

    • Department of Electrical and Computer Engineering, and NUSNNI-NanoCore, National University of Singapore
    • Department of Electrical and Computer Engineering, National University of Singapore