2025/12/04 by Cvitkovich, Lukas, Salamone, Tancredi, Wilhelmer, Christoph +3 · 1 citation
Physics and Astronomy · Engineering · #Quantum and electron transport phenomena #Semiconductor Quantum Structures and Devices #Advancements in Semiconductor Devices and Circuit Design
paper · doi:10.48550/arxiv.2512.04879
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 ``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 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 2k0 theory shall provide reasonable valley splitting statistics in many heterostructures of interest for spin qubit devices.