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