Building semiconductor nanostructures atom by atom

Atomistic tight-binding theory of multiexciton complexes in a selfassembled InAs quantum dot Zieliński, M.; Korkusiński, M.; Hawrylak, P.Contact us / Contactez nous: nparc.cisti@nrc-cnrc.gc.ca. We present atomistic tight-binding theory of electronic structure and optical properties of InAs/GaAs selfassembled quantum dots. The tight-binding model includes zincblende symmetry, faceting, and sp 3 d 5 s ‫ء‬ atomic orbitals accounting for interband and intervalley couplings. The equilibrium positions of atoms are calculated using valence force field method and modification of the tight-binding Hamiltonian due to strain is accounted for using Harrison's law. The electronic and optical properties of multiexciton complexes are then determined by diagonalizing the many-body Hamiltonian for interacting electrons and holes using the configurationinteraction approach. The calculations of strain distribution approach 10 8 atoms while the electron and valence hole single-particle states are calculated by diagonalization of the Hamiltonian matrix with size on the order of 10 7 . The dependence of predicted electronic and optical properties on InAs/GaAs valence-band offset and InAs absolute valence-band deformation potentials are described. The reliability of the atomistic calculations is assessed by comparison with results obtained from the effective bond orbital model and empirical pseudopotentials method.

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“…34 In the later part of the work we will analyze the properties of electron and hole states as a function of different strain coupling methods.…”

Section: Band Evolution As a Function Of Strainmentioning

confidence: 99%

Atomistic tight-binding theory of multiexciton complexes in a self-assembled InAs quantum dot

2010

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“…The atomistic simulations of the electronic structure of the QDM were performed in the frame of the atomistic sp 3 d 5 s* tight-binding approach in the NEMO3D implementation. 28,34 The simulation consists of two steps. In the first step we account for the presence of strain caused by the mismatch of the lattice constants of dot and barrier materials by writing the total elastic energy E TOT of the a sum of bond-stretching and bond-bending terms for each atomic bond [35][36][37] , and we adjust all atomic positions so as to minimize E TOT .…”

Section: Atomistic Tight-binding Modelmentioning

confidence: 99%

“…The equilibrium positions of atoms are further used to compute the electron and hole energies and wavefunctions in the tight-binding approach, in which the single-particle Hamiltonian is written in the form 28,34 :…”

Section: Atomistic Tight-binding Modelmentioning

confidence: 99%

Antibonding Ground States in InAs Quantum-Dot Molecules

Climente²,

et al. 2009

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Antibonding ground states in InAs quantum-dot moleculesCoherent tunneling between two InAs quantum dots forms delocalized molecular states. Using magnetophotoluminescence spectroscopy we show that when holes tunnel through a thin barrier, the lowest energy molecular state has bonding orbital character. However, as the thickness of the barrier increases, the molecular ground state changes character from a bonding orbital to an antibonding orbital, confirming recent theoretical predictions. We explain how the spin-orbit interaction causes this counterintuitive reversal by using a four-band k Á p model and atomistic calculations that account for strain.

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“…Empirical pseudopotential models (EPM) [13][14][15][16] and empirical tight-binding models (ETBM) [17][18][19][20][21][22] allow for the possibility of a microscopic description of nanostructures. While the EPM is capable of resolving variations on the atomic scale, it requires a large set of basis states, which limits the application of these models to small nanostructures.…”

Section: Introductionmentioning

confidence: 99%

Multiband effective bond-orbital model for nitride semiconductors with wurtzite structure

2010

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A multiband empirical tight-binding model for group-III-nitride semiconductors with a wurtzite structure has been developed and applied to both bulk systems and embedded quantum dots. As a minimal basis set we assume one s-orbital and three p-orbitals, localized in the unit cell of the hexagonal Bravais lattice, from which one conduction band and three valence bands are formed. Non-vanishing matrix elements up to second nearest neighbors are taken into account. These matrix elements are determined so that the resulting tight-binding band structure reproduces the known Γ-point parameters, which are also used in recent k · p-treatments. Furthermore, the tight-binding band structure can also be fitted to the band energies at other special symmetry points of the Brillouin zone boundary, known from experiment or from first-principle calculations. In this paper, we describe details of the parametrization and present the resulting tight-binding band structures of bulk GaN, AlN, and InN with a wurtzite structure. As a first application to nanostructures, we present results for the single-particle electronic properties of lens-shaped InN quantum dots embedded in a GaN matrix.

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Building semiconductor nanostructures atom by atom

Cited by 6 publications

References 54 publications

Atomistic tight-binding theory of multiexciton complexes in a self-assembled InAs quantum dot

Atomistic tight-binding theory of multiexciton complexes in a self-assembled InAs quantum dot

Antibonding Ground States in InAs Quantum-Dot Molecules

Multiband effective bond-orbital model for nitride semiconductors with wurtzite structure

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