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HL: Fachverband Halbleiterphysik

HL 11: Materials and Devices for Quantum Technology I (joint session HL/QI)

HL 11.4: Vortrag

Montag, 18. März 2024, 15:45–16:00, EW 203

Multiband k · p theory for hexagonal germanium — •Yetkin Pulcu¹, Janos Koltai², Andor Kormanyos³, and Guido Burkard¹ — ¹Department of Physics, University of Konstanz, D-78457 Konstanz, Germany — ²Department of Biological Physics, Eötvös Loránd University, Budapest, Hungary — ³Department of Physics of Complex Systems, Eötvös Loránd University, Budapest, Hungary

The direct bandgap found in hexagonal germanium and some of its alloys with silicon allows for an optically active material within the group-IV semiconductor family with various potential technological applications. However, there remain some unanswered questions regarding several aspects of the band structure, including the strength of the electric dipole transitions at the center of the BZ. In this work [2], using 10 band k· p Hamiltonian with SOC near the Γ point, we obtain a self-consistent model that describes 2H-Ge via fitting to ab initio data. To understand the weak dipole coupling between the lowest conduction band and the top valance band, we start from a spinless 12-band model and show that when adding spin-orbit coupling, the lowest conduction band hybridizes with a higher-lying conduction band. Additionally, we derive the effective low-energy Hamiltonian for the conduction bands for the possible spin dynamics and nanostructure studies. Finally, we include the effects of a magnetic field and predict the electron and hole g-factor of the conduction and valence bands.

[1] Pulcu, Yetkin, et al. "Multiband k· p theory for hexagonal germanium." arXiv preprint arXiv:2310.17366 (2023).

Keywords: Diamond structure; Elemental semiconductors; k.p method; Band structure methods