Atomistic theory of electronic and optical properties of InAsP/InP nanowire quantum dots

Cygorek, Moritz; Korkusiński, Marek; Hawrylak, Paweł

doi:10.1103/physrevb.101.075307

Cited by 34 publications

(33 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, the excitonic spectra are calculated with the configuration interaction method 2,[104][105][106][107][108] . Configuration interaction calculations are performed in a computationally challenging basis 63 involving 20 (with spin) lowestenergy electron and hole states (up to the f shell of a single cylindrical quantum dot) and leading to the total 400 excitonic configuration, wheres the largest computational cost is related to calculation of 160,000 electron-hole Coulomb integrals 105,106 over a computational box containing over 1.3 × 10 6 atoms.…”

Section: Methodsmentioning

confidence: 99%

Vanishing fine structure splitting in highly asymmetric InAs/InP quantum dots without wetting layer

Zieliński

2020

Sci Rep

View full text Add to dashboard Cite

Contrary to simplified theoretical models, atomistic calculations presented here reveal that sufficiently large in-plane shape elongation of quantum dots can not only decrease, but even reverse the splitting of the two lowest optically active excitonic states. Such a surprising cancellation of bright-exciton splitting occurs for shape-anisotropic nanostructures with realistic elongation ratios, yet without a wetting layer, which plays here a vital role. However, this non-trivial effect due to shapeelongation is strongly diminished by alloy randomness resulting from intermixing of InAs quantumdot material with the surrounding InP matrix. Alloying randomizes, and to some degree flattens the shape dependence of fine-structure splitting giving a practical justification for the application of simplified theories. Finally, we find that the dark-exciton spectra are rather weakly affected by alloying and are dominated by the effects of lateral elongation. Quantum dots 1,2 are man-made semiconductor nanostructures that come in a wide variety of types 3-5 , and are extensively studied with interest driven by both basic scientific curiosity as well as promising applications in quantum information 6 , computing 7,8 , and cryptography 9. Apart from the elementary excitations, electrons and holes, quantum dots can confine interacting electron-hole pairs, namely excitons. 10 An emission cascade from a two exciton (biexciton) state, through two indistinguishable exciton states should lead to the emission of polarization entangled photon pairs. 9,11-13 However, in realistic quantum dots the intermediate exciton state is often split by the electron-hole exchange interaction 14-16 hindering the efficiency of the entanglement generation. This energetic difference between the two bright exciton states, known as the fine-structure splitting or the bright exciton splitting (BES) is typically (10-100 µeV) much larger than the emission linewidth (∼ 1 µeV). Tailoring the BES in nanostructures is thus essential due to its relevance for photon entanglement generation. 7,11,17,18 This is particularly important for InAs/InP nanostructures, which are promising candidates for quantum emitters at 1.3 or 1.55 µm telecommunication relevant wavelengths 19-22. Notably, InAs/InP nanostructures can be fabricated in various ways, including self-assembled and nanowire quantum dots 23-27 of quasi-cylindrical shapes, as well as strongly elongated dots 28-42 , sometimes referred to as quantum dashes. Similarly to cylindrically-shaped dot systems, quantum dashes have the potential for applications 30,31,43-45 combined with considerable tuning capabilities 46,47. The manipulation of the BES aimed towards generation of entangled photon pairs is a vital and broad research area with significant efforts have been made utilizing post-growth annealing 48,49 , spectral filtering 9 , sample selection 50,51 , growth of highly symmetric structures 24,26,52-54 , and the application of external electric 55,56 , magnetic 18,57,58 , and strain fields 59-61. With respect t...

show abstract

Section: Methodsmentioning

confidence: 99%

Vanishing fine structure splitting in highly asymmetric InAs/InP quantum dots without wetting layer

Zieliński

2020

Sci Rep

View full text Add to dashboard Cite

show abstract

“…In reality, not all of these states exist due to close-by continuum states. Furthermore, the envelope wave approximation is a simplification compared to a fully atomistic treatment 47 . Finally, this approach assumes that angular momentum is a good quantum number, allowing radiative Auger with the d 0shell but not with p-shells.…”

Section: Radiative Auger Process: Theorymentioning

confidence: 99%

Radiative Auger process in the single-photon limit

et al. 2020

View full text Add to dashboard Cite

In a multi-electron atom, an excited electron can decay by emitting a photon. Typically, the leftover electrons are in their ground state. In a radiative Auger process, the leftover electrons are in an excited state and a red-shifted photon is created [1][2][3][4] . In a quantum dot, radiative Auger is predicted for charged excitons 5 . Here, we report the observation of radiative Auger on trions in single quantum dots. For a trion, a photon is created on electron-hole recombination, leaving behind a single electron. The radiative Auger process promotes this additional (Auger) electron to a higher shell of the quantum dot. We show that the radiative Auger effect is a powerful probe of this single electron: the energy separations between the resonance fluorescence and the radiative Auger emission directly measure the single-particle splittings of the electronic states in the quantum dot with high precision. In semiconductors, these single-particle splittings are otherwise hard to access by optical means as particles are excited typically in pairs, as excitons. After the radiative Auger emission, the Auger carrier relaxes back to the lowest shell. Going beyond the original theoretical proposals, we show how applying quantum optics techniques to the radiative Auger photons gives access to the single-electron dynamics, notably relaxation and tunnelling. This is also hard to access by optical means: even for quasi-resonant p-shell excitation, electron relaxation takes place in the presence of a hole, complicating the relaxation dynamics. The radiative Auger effect can be exploited in other semiconductor nanostructures and quantum emitters in the solid state to determine the energy levels and the dynamics of a single carrier.

show abstract

“…On the theoretical side, even when there exist a number of advanced approaches to investigate the electron-electron (e-e) interaction in nanostructures, usually such formalisms are limited to one or few charge carriers and to the nanometric scale [22,23,24,25,26]. Modeling of micron-long semiconductor NWs and the e-e interaction for electronic densities (n) obtained from usual doping levels (10 16 -10 19 electrons/cm 3 ) is a very cumbersome task, impracticable to carry out in a direct way.…”

Section: Introductionmentioning

confidence: 99%

Tunneling between parallel one-dimensional Wigner crystals

Méndez-Camacho

Cruz‐Hernández

2021

Preprint

View full text Add to dashboard Cite

Vertically aligned arrays are a frequent outcome in the nanowires synthesis by self-assembly techniques or in its subsequent processing. When these nanowires are close enough, quantum electron tunneling is expected between them. Then, because extended or localized electronic states can be established in the wires by tuning its electron density, the tunneling configuration between adjacent wires could be conveniently adjusted by an external gate. In this contribution, by considering the collective nature of electrons using a Yukawa-like effective potential, we explore the electron interaction between closely spaced, parallel nanowires while varying the electron density and geometrical parameters. We find that, at a low-density Wigner crystal regime, the tunneling can take place between adjacent localized states along and transversal to the wires axis, which in turn allows to create two- and three-dimensional electronic distributions with valuable potential applications.

show abstract

Atomistic theory of electronic and optical properties of InAsP/InP nanowire quantum dots

Cited by 34 publications

References 68 publications

Vanishing fine structure splitting in highly asymmetric InAs/InP quantum dots without wetting layer

Vanishing fine structure splitting in highly asymmetric InAs/InP quantum dots without wetting layer

Radiative Auger process in the single-photon limit

Tunneling between parallel one-dimensional Wigner crystals

Contact Info

Product

Resources

About