Symmetry-adapted calculations of strain and polarization fields in (111)-oriented zinc-blende quantum dots

Schulz, Stefan; Miguel, A.; O’Reilly, Eoin P.; Marquardt, Oliver

doi:10.1103/physrevb.84.125312

Cited by 59 publications

(59 citation statements)

References 78 publications

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“…However there is a set of additional terms,c 14 . To better understand these terms, we can write the stiffness matrix in the e r , e θ , e z axes, rotated with respect to the previous one by an angle θ around the The trigonal symmetry of thec 14 terms is clear, as noted in reference [27]. Note that these contributions average to…”

Section: Calculationmentioning

confidence: 99%

“…Again, the polarization in the core is along the axis, determined by −e 14 (ε xx + ε yy − 2ε zz )/ √ 3 where e 14 is the unique coefficient of the piezoelectric tensor (the indices refer to the cubic axes). A complex lanscape however emerges in the shell from the presence of in-plane and axial shear strains, and of additional terms in the piezoelectric tensor written in the trigonal axes [3,26,27].…”

Section: Summary and Electronic Propertiesmentioning

confidence: 99%

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Strain in crystalline core-shell nanowires

Ferrand

Cibert

2014

Eur. Phys. J. Appl. Phys.

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Abstract. We propose a comprehensive description of the strain configuration induced by the lattice mismatch in a core-shell nanowire with circular cross-section, taking into account the crystal anisotropy and the difference in stiffness constants of the two materials. We use an analytical approach which fully exploits the symmetry properties of the system. Explicit formulae are given for nanowires with the wurtzite structure or the zinc-blende structure with the hexagonal/trigonal axis along the nanowire, and the results are compared to available numerical calculations and experimental data on nanowires made of different III-V and II-VI semiconductors. The method is also applied to multishell nanowires, and to core-shell nanowires grown along the 0 0 1 axis of cubic semiconductors. It can be extended to other orientations and other crystal structures.

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Section: Calculationmentioning

confidence: 99%

Section: Summary and Electronic Propertiesmentioning

confidence: 99%

Strain in crystalline core-shell nanowires

Ferrand

Cibert

2014

Eur. Phys. J. Appl. Phys.

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“…The relevant strain tensor elements were obtained by minimizing an elastic energy. The piezoelectric potential is calculated up to second order in polarization [35,36] using the piezoelectric coefficients from Ref. [37].…”

Section: Modeling Of the Electric Field Dependent Energy Structure Bamentioning

confidence: 99%

“…Due to the zincblende structure of the In x Ga 1−x As crystal, the shear strain induces a piezoelectric field that we take into account up to second order in polarization [35,36] using the parameters from Ref. 37.…”

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confidence: 99%

Coulomb Mediated Hybridization of Excitons in Coupled Quantum Dots

et al. 2016

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We report the Coulomb mediated hybridization of excitonic states in an optically active, artificial quantum dot molecule. By probing the optical response of the artificial molecule as a function of the static electric field applied along the molecular axis, we observe unexpected avoided level crossings that do not arise from the dominant single particle tunnel coupling. We identify a new few-particle coupling mechanism stemming from Coulomb interactions between different neutral exciton states. Such Coulomb resonances hybridize the exciton wave function over four different electron and hole single-particle orbitals. Comparisons of experimental observations with microscopic 8-band k · p calculations taking into account a realistic quantum dot geometry show good agreement and reveal that the Coulomb resonances arise from broken symmetry in the artificial molecule.Understanding and controlling the fundamental interactions that couple discrete quantum states lies at the very heart of applied quantum science. For example, couplings between distinct physical subsystems mediated by the Coulomb interaction can be used to entangle qubits electrostatically [1], to build single-photon transistors on the basis of Förster resonances [2] or to control resonant energy transfer [3]. Strong tunnel couplings between proximal quantum dots have been shown to facilitate electrical and optical spin-qubit operations [4,5] while long range magnetic dipolar interactions have been exploited for prototype quantum registers [6]. Thus the nature of quantum couplings has been under extensive investigation for many prototypical quantum systems. Examples include naturally occurring atoms [3,7,8] and defect centers [9,10] as well as artificial atoms and molecules [11][12][13]. Due to advanced nanostructure fabrication techniques [14,15] and efficient coupling to light [16,17], artificial molecules consisting of pairs of semiconductor quantum dots (QDs) have emerged as ideal prototypical solid-state systems to investigate and electrically control interactions between proximal quantum systems [11,12].By embedding a QD-molecule into the intrinsic region of a diode structure, exciton states in the different QDs can be tuned into and out of resonance by controlling the electric field along the growth direction [11,12]. The fundamental signatures of quantum couplings are avoided level crossings in the electronic energy level structure of a QD-molecule as single particle states are tuned in and out of resonance [18]. The importance of Coulomb interactions has been pointed out for the form and position of resonances in QD-molecule systems [19][20][21]. However, single particle tunneling that either hybridizes single electrons or holes remains the dominant coupling mechanism in these cases [11][12][13][22][23][24][25]. Most recently another resonant coupling mechanism with an inherently two particle nature has been predicted theoretically that entirely relies on the Coulomb mediated interaction between two different exciton states [26]. In strong contra...

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“…It is present even without strain and originates from the inversion symmetry breaking along the c axis in the WZ lattice. [62] The spontaneous polarization in WZ systems is a constant vector in the z direction, P sp = (0, 0, P sp ), where P sp is material dependent. Therefore, the total polarization P(r) coming from both contributions is given by …”

Section: Piezoelectric Polarization In [001]-grown Zb Structuresmentioning

confidence: 99%

Electronic structure of quantum dots: response to the environment and externally applied fields

Ortí¹

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AgraïmentsLa present Tesi doctoralés el resultat final de quatre anys de treball i esforç en què he tingut la sort de comptar amb el suport de companys, familiars i amics que han compartit amb mi aquesta enriquidora experiència. Sens dubte, el treball que ací es mostra no haguera sigut possible sense la seua ajuda.En primer lloc, voldria agrair a Josep Planelles i Juan Ignacio Climente el haver-me oferit la possibilitat de realitzar aquest projecte de Tesi sota la seua supervisió. Durant tot el temps que he tingut el plaer de treballar amb ells han mostrat un gran interès i una dedicació plena en proporcionar-me la millor formació investigadora tenint sempre present el que seria millor per al meu futur. De la mateixa manera, el meu agraïmentés extensiu a la resta de membres del grup de Química Quàntica Fernando Rajadell, José Luis Movilla, Miquel Royo i Ana Ballester que d'una manera o altra han contribuït a la realització d'aquesta Tesi. En especial vull destacar a Ana B, amb qui vaig tindre la sort de compartir laboratori durant els primers anys de doctorat i que prompte es va convertir en una molt bona amiga. D'altra banda, voldria mostrar també la meua gratitud als amics que han estat al meu costat en el dia a dia durant aquests anys i que han compartit amb mi molts bons moments dintre i fora de la universitat. En concret vull destacar a Ana M, David, Erica, Neus, Paula i, com no, a chéritounet Loucou. A més, cal mencionar a tots els membres del Departament de Química Física i Analítica, especialment a Merche per la seva predisposició a ajudar-me amb tota la paperassa i els tràmits burocràtics. Done també les gràcies a Sergio E. Ulloa per donar-me l'oportunitat de realitzar una estada breu en el seu grup de recerca en la Universitat d'Ohio (Estats Units), així com a tots els membres del grup per la seua acollida.Finalment, voldria agrair de cor als meus pares el suport i la confiança incondicionals que m'han donat durant tota la meua vida. Perquè són els principals responsables de que haja arribat fins ací, els dedique aquesta Tesi.

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Symmetry-adapted calculations of strain and polarization fields in (111)-oriented zinc-blende quantum dots

Cited by 59 publications

References 78 publications

Strain in crystalline core-shell nanowires

Strain in crystalline core-shell nanowires

Coulomb Mediated Hybridization of Excitons in Coupled Quantum Dots

Electronic structure of quantum dots: response to the environment and externally applied fields

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