Regensburg 2022 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 3: Quantum Dots and Wires 1: Transport and Electronic Properties
HL 3.11: Talk
Monday, September 5, 2022, 12:45–13:00, H32
Band structure and end states in InAs/GaSb core-shell-shell nanowires — •Florinda Viñas Boström1,2, Athanasios Tsintzis2, Michael Hell2, and Martin Leijnse2 — 1Institute for Mathematical Physics, TU Braunschweig, Braunschweig, Germany — 2Division of Solid State Physics and NanoLund, Lund University, Lund, Sweden
Heterostructures made from the III-V semiconductors InAs and GaSb have been studied mainly for their bulk broken band gap alignment, meaning that the valence band of GaSb is higher in energy than the conduction band in InAs, in bulk. In addition, the materials are nearly lattice matched, leading to structures with almost no strain. In two dimensions, the InAs/GaSb quantum well is a topological insulator, exhibiting a hybridization gap in the topologically non-trivial regime where quantum spin Hall edge states are present. We have calculated the non-trivial band structures and wave functions of InAs/GaSb core-shell-shell nanowires, using k· p theory. For hollow core-shell-shell InAs/GaSb nanowires, we also calculate the wave functions for a finite system with wire ends, using a BHZ model with parameters taken from the resulting k· p calculations. We establish that there are localized end-states, with energies inside the bulk gap. However, in contrast to the topological edge states in two dimensions, these end states are fourfold degenerate, and split into two Kramers pairs under potential disorder along the nanowire growth direction. Nevertheless, the end states are robust against potential disorder applied in the angular direction, as long as the bulk band gap is not closed.