Singlet-triplet splitting of two electrons in a Si/SiGe quantum dot

ORAL

Abstract

We theoretically study the effects of quantum dot confinement strength on the singlet-triplet (ST) splitting of two-electron dots in Si/SiGe quantum wells. Our analysis includes valley effects and disorder at the quantum well interface by combining full configuration interaction (FCI) scheme with tight-binding (TB) calculations. While TB provides an accurate description of single-electron wave functions by taking microscopic effects like interface disorder into account, and captures the valley physics of silicon, FCI allows us to calculate multielectron energies and corresponding wave functions by including the effects of electron-electron interactions. We show that these interactions can have unexpectedly strong or unexpectedly weak effects on the ST splitting, depending on the confinement strength and anisotropy.

*This work was supported by the Vannevar Bush Faculty Fellowship program sponsored by the Basic Research Office of the Assistant Secretary of Defense for Research and Engineering and funded by the Office of Naval Research through Grant No. N00014-15-1-0029, and by ARO through Award No. W911NF-17-1-0274.

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Presenters

  • Ekmel Ercan

    • University of Wisconsin - Madison

Authors

  • Ekmel Ercan

    • University of Wisconsin - Madison

  • Susan Nan Coppersmith

    • University of Wisconsin - Madison
    • University of New South Wales, Sydney, Australia
    • Department of Physics, University of Wisconsin-Madison
    • University of Wisconsin-Madison
    • University of New South Wales
    • University of Wisconsin-Madison, The University of New South Wales

  • Mark G Friesen

    • University of Wisconsin - Madison
    • Department of Physics, University of Wisconsin-Madison, Madison WI, USA
    • University of Wisconsin-Madison