Strong dipole coupling in nonpolar nitride quantum dots due to Coulomb effects

We present an atomistic description of the electronic and optical properties of In0.25Ga0.75N/GaN quantum wells. Our analysis accounts for fluctuations of well width, local alloy composition, strain and built-in field fluctuations as well as Coulomb effects. We find a strong hole and much weaker electron wave function localization in InGaN random alloy quantum wells. The presented calculations show that while the electron states are mainly localized by well-width fluctuations, the holes states are already localized by random alloy fluctuations. These localization effects affect significantly the quantum well optical properties, leading to strong inhomogeneous broadening of the lowest interband transition energy. Our results are compared with experimental literature data.

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“…II A. The built-in potential φ(r) is likewise included as a site-diagonal contribution in the TB Hamiltonian [33][34][35][36].…”

Section: B Electronic Structure Calculationsmentioning

confidence: 99%

Atomistic analysis of the impact of alloy and well-width fluctuations on the electronic and optical properties of InGaN/GaN quantum wells

Schulz¹,

et al. 2015

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“…Previous studies on InGaN QD systems assumed lens-shaped geometries [39,40]. We followed this assumption, and based on earlier AFM results [33], chose a base diameter of 30 nm and a height of 2.5 nm as our starting point, with indium content varied between 15% and 25%.…”

Section: Theoretical Calculations Of Dolpmentioning

confidence: 99%

Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

et al. 2017

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Abstract:We report the direct generation of linearly polarized single photons with a deterministic polarization axis in self-assembled quantum dots (QDs), achieved by the use of non-polar InGaN without complex device geometry engineering. Here, we present a comprehensive investigation of the polarization properties of these QDs and their origin with statistically significant experimental data and rigorous k·p modeling. The experimental study of 180 individual QDs allows us to compute an average polarization degree of 0.90, with a standard deviation of only 0.08. When coupled with theoretical insights, we show that these QDs are highly insensitive to size differences, shape anisotropies, and material content variations. Furthermore, 91% of the studied QDs exhibit a polarization axis along the crystal [1-100] axis, with the other 9% polarized orthogonal to this direction. These features give non-polar InGaN QDs unique advantages in polarization control over other materials, such as conventional polar nitride, InAs, or CdSe QDs. Hence, the ability to generate single photons with polarization control makes non-polar InGaN QDs highly attractive for quantum cryptography protocols.

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“…3 The electrostatic built-in field and its impact on the electronic and optical properties have been studied theoretically. 6,8,9 The properties of a-plane GaN/AlN QDs have been discussed in Ref. 6.…”

mentioning

confidence: 99%

Prediction of strong ground state electron and hole wave function spatial overlap in nonpolar GaN/AlN quantum dots

Schulz¹,

Miguel

O’Reilly

2012

Applied Physics Letters

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We present a detailed analysis of the electrostatic built-in field, the electronic structure, and the optical properties of a-plane GaN/AlN quantum dots with an arrowhead-shaped geometry. This geometry is based on extensive experimental analysis given in the literature. Our results indicate that the spatial overlap of electron and hole ground state wave functions is significantly increased, compared to that of a c-plane system, when taking the experimentally suggested trapezoid-shaped dot base into account. This finding is in agreement with experimental data on the optical properties of a-plane GaN/AlN quantum dots. (C) 2012 American Institute of Physics. (http://dx.doi.org/10.1063/1.4752108

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Strong dipole coupling in nonpolar nitride quantum dots due to Coulomb effects

Cited by 21 publications

References 25 publications

Atomistic analysis of the impact of alloy and well-width fluctuations on the electronic and optical properties of InGaN/GaN quantum wells

Atomistic analysis of the impact of alloy and well-width fluctuations on the electronic and optical properties of InGaN/GaN quantum wells

Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

Prediction of strong ground state electron and hole wave function spatial overlap in nonpolar GaN/AlN quantum dots

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