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HL: Fachverband Halbleiterphysik

HL 18: Quantum dots and wires I

HL 18.8: Vortrag

Montag, 16. März 2020, 17:30–17:45, POT 151

Efficient electronic structure calculations for extended systems of coupled quantum dots for Quantum Cascade Lasers Based on a Quantum Dot Superlattice — •Alexander Mittelstädt and Andrei Schliwa — Institut für Festkörperphysik, Technische Universität Berlin

We present a linear combination of atomic orbitals–type of approximation, enabling accurate electronic structure calculations for systems of up to 20 or more electronically coupled quantum dots. Using realistic single quantum dot wavefunctions as basis to expand the eigenstates of the heterostructure, our method shows excellent agreement with full 8-band k·p calculations, exemplarily chosen for our benchmarking comparison, with an orders of magnitude reduction in computational time. We show that, in order to correctly predict the electronic properties of such stacks of coupled quantum dots, it is necessary to consider the strain distribution in the whole heterostructure. Edge effects determine the electronic structure for stacks of  10 QDs, after which a homogeneous confinement region develops in the center. The overarching goal of our investigations is to design a stack of vertically coupled quantum dots with an intra-band staircase potential suitable as active material for a quantum-dot-based quantum cascade laser.