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arXiv · 2512.04879

Valley Splittings in Si/SiGe Heterostructures from First Principles

Lukas Cvitkovich·Tancredi Salamone·Christoph Wilhelmer·Biel Martinez·Tibor Grasser·Yann-Michel Niquet
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Abstract

We compute valley splittings in Si/SiGe superlattices using ab initio density functional theory (DFT). This first-principle 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 ``$2k_0$'' theory within the effective mass (EM) approximation against DFT. We show that DFT supports the main conclusions of the 2$k_0$ theory, but reveals some limitations of semi-empirical 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 splittings. Nevertheless, TB and the 2$k_0$ theory shall provide reasonable valley splitting statistics in many heterostructures of interest for spin qubit devices.

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Lukas Cvitkovich, Tancredi Salamone, Christoph Wilhelmer, Biel Martinez, Tibor Grasser, Yann-Michel Niquet. 2025-12-04. Valley Splittings in Si/SiGe Heterostructures from First Principles. https://arxiv.org/abs/2512.04879

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