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O: Fachverband Oberflächenphysik

O 10: Focus Session: Frontiers of Electronic-Structure Theory – Advances in Time-Dependent and Nonequilibrium Ab Initio Methods II

O 10.2: Talk

Monday, March 18, 2024, 15:15–15:30, HE 101

Anisotropic Charge, Thermal, and Thermoelectric Transport in β-Ga₂O₃ from First Principles — •Sebastian Tillack, Nakib Protik, and Claudia Draxl — Humboldt-Universität zu Berlin and IRIS Adlershof, 12489 Berlin, Germany

Gallium oxide gained interest for high-power applications due to its large band gap of ∼ 5 eV and a high breakdown voltage. On the other hand it shows only modest electron mobility and relatively low thermal conductivity. While the latter is a clear limitation for power electronics it might render the material useful for thermoelectric applications.

We present an ab initio study of transport in β-Ga₂O₃ including electron–phonon and phonon–phonon interactions. Electrons and phonons are described within a full-potential all-electron framework [1] using many-body perturbation theory and density-functional perturbation theory. Maximally localized Wannier functions and Wannier-Fourier interpolation facilitate ultra fine samplings of the Brillouin zone. We solve the coupled electron–phonon Boltzmann transport equations [2] to compute the anisotropic electron mobility, Seebeck coefficient and thermal conductivity for different temperatures and electron doping levels, and the effect of the mutual electron–phonon drag on these transport coefficients. Our work provides insight into the fundamental scattering processes limiting transport in this material and explores its usefulness for various applications.

[1] A. Gulans, et al., J. Phys.: Condens. Matter 26, 363202 (2014).
[2] N.H. Protik, et al., npj Comput. Mater. 8, 28 (2022).

Keywords: G2O3; electron-phonon; Wannier; transport