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Valley splitting in Si/SiGe heterostructures from first principles

Lukas Cvitkovich1,*, Tancredi Salamone2, Christoph Wilhelmer1, Biel Martinez2, Tibor Grasser1, and Yann-Michel Niquet3

  • *Contact author: cvitkovich@iue.tuwien.ac.at
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Phys. Rev. B 113, 035307 – Published 20 January, 2026

DOI: https://doi.org/10.1103/frx3-41bz

Abstract

We compute valley splitting in Si/SiGe superlattices using ab initio density functional theory (DFT). This first-principles approach is expected to provide an excellent description of interfaces, strains, and atomistic disorder without empirically fitted parameters. We benchmark atomistic tight-binding (TB) and the “2k0” theory within the effective mass (EM) approximation against DFT. We show that DFT supports the main conclusions of the 2k0 theory, but reveals some limitations of semiempirical methods such as the EM and TB, in particular about the description of atomistic disorder. The DFT calculations also highlight the effects of strong valley-orbit mixing at large valley splitting. Nevertheless, TB and the 2k0 theory shall provide reasonable valley splitting statistics in many heterostructures of interest for spin qubit devices.

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Phys. Rev. B 113, 035307– Published 20 January, 2026
  • Received 31 March 2025
  • Revised 4 December 2025
  • Accepted 5 January 2026
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