Excitonic fine structure splitting in type-II quantum dots

Křápek, Vlastimil; Klenovský, Petr; Šikola, Tomáš

doi:10.1103/physrevb.92.195430

Cited by 27 publications

(27 citation statements)

References 96 publications

(52 reference statements)

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“…We further note that considerably smaller FSS for type II corroborates with the results of Refs. [81,82,84] for (In,Ga)As/Ga(As,Sb)/GaAs QDs and, in turn, confirms that to be a rather general property of dots which are type-II in real space. The correlation is obtained in our CI calculations through admixing of excited single-particle states [69].…”

Section: γ-Excitonssupporting

confidence: 66%

“…We note that the calculations of FSS and ∆E bd shown in Fig. 11 were performed with two electron and two hole single-particle basis states and expanded the exchange interaction into a multipole series [81,83]. Following Ref.…”

Section: γ-Excitonsmentioning

confidence: 99%

“…Following Ref. [81] we considered the following terms of that expansion: monopole-monopole (EX 0 ), monopoledipole (EX 1 ), and dipole-dipole (EX 2 ). We find that irrespective of the substrate material (GaP or GaAs) the FSS in our system is dominated by EX 2 .…”

Section: γ-Excitonsmentioning

confidence: 99%

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Electronic states of (InGa)(AsSb)/GaAs/GaP quantum dots

2019

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Detailed theoretical studies of the electronic structure of (InGa)(AsSb)/GaAs/GaP quantum dots are presented. This system is unique since it exhibits concurrently direct and indirect transitions both in real and momentum space and is attractive for applications in quantum information technology, showing advantages as compared to the widely studied (In,Ga)As/GaAs dots. We proceed from the inspection of the confinement potentials for k = 0 and k = 0 conduction and k = 0 valence bands, through the formulation of k · p calculations for k-indirect transitions, up to the excitonic structure of Γ-transitions. Throughout this process we compare the results obtained for dots on both GaP and GaAs substrates, enabling us to make a direct comparison to the (In,Ga)As/GaAs quantum dot system. We also discuss the realization of quantum gates.

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Section: γ-Excitonssupporting

confidence: 66%

Section: γ-Excitonsmentioning

confidence: 99%

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Electronic states of (InGa)(AsSb)/GaAs/GaP quantum dots

2019

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“…The matrix elements of the Coulomb Hamiltonian were calculated following the approach of Refs. [3,16].…”

Section: Theorymentioning

confidence: 99%

Type-I and Type-II Confinement in Quantum Dots: Excitonic Fine Structure

2016

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We have theoretically studied type-I and type-II confinement in InAs quantum dots with GaAs1−ySby capping layer. The character of the confinement can be adjusted by the Sb content. We have found that upon the transition from type-I to type-II confinement the hole wave functions change the topology from a compact shape to a twosegment shape, resulting in the complex changes in the exciton fine structure splitting with zero values at particular compositions. Additionally, a high exciton radiative recombination probability is preserved even in type-II. This allows to design strongly luminescent quantum dots with naturally low fine structure splitting, which could serve as sources of entangled photon pairs for quantum communication.

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“…This reduced mixing is also indicative of a reduced FSS in site-controlled (111)-oriented InGaAs/GaAs QDs. 21 Furthermore, we show that the anisotropy in E α p and the p-state splitting reduce with increasing the QD lateral size. Since the size of the here considered QDs is at the lower limit of the experimentally realized structures, our results indicate that the larger QDs are even more promising for achieving entangled photon generation, and support thus the potential of site-controlled (111)-oriented InGaAs/GaAs QDs as polarization entangled photon emitters in future quantum information applications.…”

Section: Discussionmentioning

confidence: 71%

Theoretical analysis of influence of random alloy fluctuations on the optoelectronic properties of site-controlled (111)-oriented InGaAs/GaAs quantum dots

Benchamekh¹,

Schulz²,

O’Reilly

2016

Phys. Rev. B

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We use an sp 3 d 5 s * tight-binding model to investigate the electronic and optical properties of realistic site-controlled (111)-oriented InGaAs/GaAs quantum dots. Special attention is paid to the impact of random alloy fluctuations on key factors that determine the fine-structure splitting in these systems. Using a pure InAs/GaAs quantum dot as a reference system, we show that the combination of spin-orbit coupling and biaxial strain effects can lead to sizeable spin-splitting effects in these systems. Then, a realistic alloyed InGaAs/GaAs quantum dot with 25% InAs content is studied. Our analysis reveals that the impact of random alloy fluctuations on the electronic and optical properties of (111)-oriented InGaAs/GaAs quantum dots reduces strongly as the lateral size of the dot increases and approaches realistic sizes. For instance the optical matrix element shows an almost vanishing anisotropy in the (111)-growth plane. Furthermore, conduction and valence band mixing effects in the system under consideration are strongly reduced compared to standard (100)-oriented InGaAs/GaAs systems. All these factors strongly indicate a reduced fine structure splitting in site-controlled (111)-oriented InGaAs/GaAs quantum dots. Thus, we conclude that quantum dots with realistic (50-80 nm) base length represent promising candidates for polarization entangled photon generation, consistent with recent experimental data.

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Excitonic fine structure splitting in type-II quantum dots

Cited by 27 publications

References 96 publications

Electronic states of (InGa)(AsSb)/GaAs/GaP quantum dots

Electronic states of (InGa)(AsSb)/GaAs/GaP quantum dots

Type-I and Type-II Confinement in Quantum Dots: Excitonic Fine Structure

Theoretical analysis of influence of random alloy fluctuations on the optoelectronic properties of site-controlled (111)-oriented InGaAs/GaAs quantum dots

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