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Closing the loop on valley splitting in <sup>28</sup>Si/SiGe: atom probe tomography, tightbinding, and cryomultiplexing

ORAL

Abstract

28Si/SiGe heterostructures provide a compelling host material for a scalable quantum computer, due to the long coherence times of spin qubits and compatibility with industry. Here we study 28Si/SiGe heterostructures with varying roughness of the critical Si/SiGe interfaces to understand the energy splitting of the lowest lying conduction valleys (valley splitting). To improve control of valley splitting in 28Si/SiGe, we implement a feedback cycle for materials stack engineering including several elements.
We use atom probe tomography to provide atomic 3D reconstruction of the material stack and statistical understanding of compositional variations at the Si/SiGe interface over nanoscale dimensions relevant for spin qubits. The resulting data is fed into a tight binding model to compute the valley splitting in real quantum wells with varying thickness, Si/SiGe interface width, and interface chemical roughness. We complete the cycle by comparing the simulation results with valley splitting measured in heterostructure field effect transistors and quantum dots, making use of cryomultiplexer technology to achieve statistically significant metrics.
We envision that such a feedback loop may help to engineer optimal stacks for large and controllable values of valley splitting in Si/SiGe.

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Presenters

  • Brian Paquelet Wuetz

    Delft University of Technology

Authors

  • Brian Paquelet Wuetz

    Delft University of Technology

  • Merritt Losert

    Department of Physics, University of Wisconsin-Madison

  • Sebastian Koelling

    Department of Engineering Physics, École Polytechnique de Montréal, Ecole Polytechnique de Montreal

  • Anne-Marije Zwerver

    Delft University of Technology, QuTech, Delft University of Technology

  • Lucas Stehouwer

    Delft University of Technology

  • Nodar Samkharadze

    QuTech and Netherlands Organisation for Applied Scientific Research (TNO), TNO

  • Stephan Philips

    Delft University of Technology, Qutech, Delft University of Technology

  • Mateusz T Madzik

    Delft University of Technology, QuTech, Delft University of Technology, Univ of New South Wales

  • Guoji Zheng

    Delft University of Technology

  • Xiao Xue

    Delft University of Technology

  • Sergei Amitonov

    Delft University of Technology, QuTech, Delft University of Technology

  • Mario Lodari

    Delft University of Technology, QuTech and Kavli Institute of Nanoscience, Delft University of Technology

  • Amir Sammak

    QuTech and Netherlands Organisation for Applied Scientific Research (TNO), TNO, QuTech, Delft University of Technology, Netherlands Organization for Applied Scientific Research (TNO), Delft University of Technology

  • Susan N Coppersmith

    School of Physics, University of New South Wales

  • Lieven Vandersypen

    Delft University of Technology, Qutech and Kavli Institute of Nanoscience, Delft University of Technology, QuTech, Delft University of Technology, QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Qutech, Delft University of Technology

  • Oussama Moutanabbir

    Department of Engineering Physics, École Polytechnique de Montréal, Ecole Polytechnique de Montreal

  • Mark G Friesen

    Department of Physics, University of Wisconsin-Madison, University of Wisconsin - Madison

  • Giordano Scappucci

    Delft University of Technology, QuTech, Delft University of Technology, QuTech and Kavli Institute of Nanoscience, TU Delft, QuTech and Kavli Institute of Nanoscience, Delft University of Technology