Density dependence of the excitation gap in Si/SiGe bilayers

ORAL

Abstract

We report low-temperature magneto-transport measurements of an undoped Si/SiGe antisymmetric double quantum well heterostructure . The density in both layers is tuned independently utilizing a top and a bottom gate, allowing the investigation of both density matched and mis-matched quantum wells. A cross-over density, distinguishing the single-layer from the bi-layer regime, is clearly observed from the mobility versus density curve. Additionally, the integer quantum Hall states at total filling factor νT=1,2 are observed at both matched and mis-matched densities. These states arise from inter-layer effects; either through inter-layer coherence, or through the symmetric-antisymmetric tunneling gap. To disentangle these two mechanisms, the evolution of the filling fraction’s excitation gap is studied as a function of density.

*SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525

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Presenters

  • Davis Chen

    • Department of Physics, University of Florida

Authors

  • Davis Chen

    • Department of Physics, University of Florida

  • Suyang Cai

    • Department of Physics, University of Florida

  • Nai-Wen Hsu

    • Department of Electrical Engineering and Graduate Institute of Electronic Engineering, National Taiwan University

  • Shi-Hsien Huang

    • Department of Electrical Engineering and Graduate Institute of Electronic Engineering, National Taiwan University

  • Yen Chuang

    • Department of Electrical Engineering and Graduate Institute of Electronic Engineering, National Taiwan University

  • Jiun-Yun Li

    • National Taiwan University
    • Department of Electrical Engineering and Graduate Institute of Electronic Engineering, National Taiwan University

  • Chee Wee Liu

    • Department of Electrical Engineering and Graduate Institute of Electronic Engineering, National Taiwan University

  • Tzu-Ming Lu

    • Sandia National Laboratories
    • Sandia National Laboratories, Center for Integrated Nanotechnologies
    • Center for Integrated Nanotechnologies, Sandia National Laboratories

  • Dominique Laroche

    • University of Florida
    • Department of Physics, University of Florida