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Quantum Dot Molecules (quantum + dot_molecule)
Selected AbstractsQuantum Dots: Self-Assembled Quantum Dot Molecules (Adv. Mater.ADVANCED MATERIALS, Issue 25-26 200926/2009) The cover shows a 2D photoluminescence intensity map from a self-assembled lateral quantum dot molecule in an electric field applied along the molecular axis. The coupling of the two quantum dots is evidenced by intricate spectral line anticrossings, indicated by dotted lines, as reported in the review by Lijuan Wang and co-workers on p. 2601. A 3D AFM image of a lateral quantum dot molecule overlapped with the ground-state electron wavefunction is shown in the inset. [source] Self-Assembled Quantum Dot MoleculesADVANCED MATERIALS, Issue 25-26 2009Lijuan Wang Abstract Semiconductor quantum dot molecules (QDMs) are systems composed of two or more closely spaced and interacting QDs. QDMs are receiving much attention both as playground for studying coupling and energy transfer processes between "artificial atoms" and as new systems, which substantially extend the range of possible applications of QDs. QDMs can be conveniently fabricated by self-assembly either through chemical synthesis or epitaxial growth. Although QDMs relying on the random occurrence of nearby QDs can be used for fundamental studies, special fabrication protocols must be used to create QDMs with well-defined properties. In this article, we focus on self-assembled QDMs obtained by epitaxial growth and embedded in a semiconductor matrix, which are appealing for the possible realization of quantum gates based on two-level systems defined in QDs. We provide a comprehensive overview of the development and current stage of the research on QDMs composed of vertically (in the growth direction) or laterally (in the growth plane) aligned QDs. The review highlights some recent milestone works and points out the challenges and future directions in the field. [source] Quantum Dots: Self-Assembled Quantum Dot Molecules (Adv. Mater.ADVANCED MATERIALS, Issue 25-26 200926/2009) The cover shows a 2D photoluminescence intensity map from a self-assembled lateral quantum dot molecule in an electric field applied along the molecular axis. The coupling of the two quantum dots is evidenced by intricate spectral line anticrossings, indicated by dotted lines, as reported in the review by Lijuan Wang and co-workers on p. 2601. A 3D AFM image of a lateral quantum dot molecule overlapped with the ground-state electron wavefunction is shown in the inset. [source] Strong coupling in artificial semimagnetic Cd(Mn,Mg)Te quantum dot moleculePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 15 2006S. V. Zaitsev Abstract Exciton photoluminescence in a pair of strongly coupled artificial asymmetric quantum dots (QDs) has been studied in a magnetic field up to 8 T. The QD molecules have been fabricated by a selective interdiffusion technique applied to asymmetric semimagnetic CdTe/Cd(Mg,Mn)Te double quantum wells. The lateral confinement potential within the plane, induced by the diffusion, gives rise to effective zero-dimensional exciton localization. In contrast to a typically positive exciton Lande g -factor, an exciton transition in the non-magnetic QD demonstrates a nearly zero g -factor, indicating a strong electron tunnel coupling between the QDs. The strong coupling results in the formation of an inter-QDs indirect exciton, which is a ground exciton state at high magnetic field, as found in the experiment and confirmed by our calculations. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Linear excitonic absorption under an external electric field in quantum dot moleculesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2007M. Bedoya Abstract A study of the excitonic states in artificial molecules set up of two vertically coupled double quantum dots is presented. The electron and hole eigenstates are calculated for the quantum dot molecule. In particular, the coupling effect of the barrier and the consequent tunneling is analyzed following the evolution of the absorption spectra as function of the distance between the two dots. On the other hand, the role of the Coulomb correlation between the confined particles is also studied. We present results of relevant interactions in these systems and discuss how the optical properties of double quantum dots are affected by the interdot coupling, by the geometry of the dots and by an applied electric field. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Self-Assembled Quantum Dot MoleculesADVANCED MATERIALS, Issue 25-26 2009Lijuan Wang Abstract Semiconductor quantum dot molecules (QDMs) are systems composed of two or more closely spaced and interacting QDs. QDMs are receiving much attention both as playground for studying coupling and energy transfer processes between "artificial atoms" and as new systems, which substantially extend the range of possible applications of QDs. QDMs can be conveniently fabricated by self-assembly either through chemical synthesis or epitaxial growth. Although QDMs relying on the random occurrence of nearby QDs can be used for fundamental studies, special fabrication protocols must be used to create QDMs with well-defined properties. In this article, we focus on self-assembled QDMs obtained by epitaxial growth and embedded in a semiconductor matrix, which are appealing for the possible realization of quantum gates based on two-level systems defined in QDs. We provide a comprehensive overview of the development and current stage of the research on QDMs composed of vertically (in the growth direction) or laterally (in the growth plane) aligned QDs. The review highlights some recent milestone works and points out the challenges and future directions in the field. [source] Theory of electronic and transport properties of resonant triple quantum dot moleculesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2009Y.-P. Shim Abstract We present a theory of electronic and transport properties of triple quantum dot molecules in the vicinity of quadruple points where four different charge configurations are on resonance. We study three different quadruple points in the presence of a magnetic field and show that a trapped particle in one of the dot plays an essential role in determining the spin character of the transport. Many-electron states of the triple quantum dot molecules are used as transport channels in the Fermi's Golden Rule approach and it is demonstrated that the Aharonov,Bohm oscillations of the energy spectrum lead to spin-selective oscillations in transport. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Linear excitonic absorption under an external electric field in quantum dot moleculesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2007M. Bedoya Abstract A study of the excitonic states in artificial molecules set up of two vertically coupled double quantum dots is presented. The electron and hole eigenstates are calculated for the quantum dot molecule. In particular, the coupling effect of the barrier and the consequent tunneling is analyzed following the evolution of the absorption spectra as function of the distance between the two dots. On the other hand, the role of the Coulomb correlation between the confined particles is also studied. We present results of relevant interactions in these systems and discuss how the optical properties of double quantum dots are affected by the interdot coupling, by the geometry of the dots and by an applied electric field. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Excitonic polaron in InAs/GaAs self-assembled quantum dot moleculesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2007M. Adames Abstract We study the excitonic polaron formation in two InAs/GaAs coupled quantum dots. We calculate the coupling between the exciton and the LO-phonon states by using the Fröhlich Hamiltonian, from which we determine the excitonic polaron states varying the quantum dot separation. We study the dependence on the excitonic polaron formation with the coupling between the dots. Polaron formation strongly modifies the energy spectra due to the appearance of several anticrossings in the excited states. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||