Ten million-atom InGaAs embedded quantum dot electron g factor calculations using semi-empirical pseudopotentials

Date
2022-10
Advisor
Bulutay, Ceyhun
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Bilkent University
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English
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Thesis
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Abstract

Quantum technologies rely on key capabilities such as electron spin control over the full-Bloch sphere, generation of indistinguishable single photons, or entangled photon pairs. For all these purposes, arguably the most established semiconductor structure currently is the self-assembled InGaAs quantum dots (QDs). In this thesis, electron ground state g tensors of embedded InGaAs QDs are calculated employing an atomistic empirical pseudopotential method. Computed QDs have varied size, shape, indium molar fraction but uniform strain. The components of the g tensor do not show appreciable deviation even though the shape is anisotropic for some of the studied QDs. Universality is observed when family of g factor curves is plotted with respect to energy gap which generalizes the findings of a recent study under more restricted conditions. Our work expands its applicability to alloy QDs with different shapes, and finite confinement putting it on a more realistic foundation by allowing penetration to the matrix material. Our regression model shows that the effect of magnetic field on the electron in an InGaAs QD will be the minimal when the so-called, s-shell optical transition energy is around 1.13 eV. Furthermore, low indium molar fraction is unfavorable in terms of g factor tunability. Our findings could be beneficial in the fabrication of g-near-zero QDs or other desired g values aimed for spintronic or electron spin resonance applications.

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Keywords
g factor, g tensor, Quantum dot, Atomistic electronic structure, InGaAs
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Published Version (Please cite this version)