Vertically Self-Organized InAs Quantum Box Islands on GaAs(100)

Xie, Qiwei; Madhukar, A.; Chen, Ping; Kobayashi, Nobuhiko P.

doi:10.1103/physrevlett.75.2542

Cited by 1,359 publications

(834 citation statements)

References 14 publications

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“…It has been proposed that dot ordering is driven by the elastic field of the subsurface stressors. Usually, these subsurface stressors are buried dots themselves [14,15]; however, they can take the form of subsurface dislocation arrays [16] or buried strained layers on patterned substrates [7,17]. Subsurface stressors lead to a modulation in the stress field and associated strain field on the growth surface, which impacts both adatom diffusion and island nucleation rates [15,18].…”

Section: Introductionmentioning

confidence: 99%

Elastic fields and energies of coherent surface islands

Jónsdóttir

Halldorsson

Beltz

et al. 2006

Modelling Simul. Mater. Sci. Eng.

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We present simple models based on isotropic elasticity for determining the stress fields in the vicinity of, and the elastic energy associated with, coherent surface islands (i.e. a quantum dot or a nanorod). The first method treats the surface island as an areal point of dilatation and does not account for details of the island shape. Next, the finite element method is used to study simple island shapes such as spherical caps and cylinders, with a particular focus on the island aspect ratio. The latter is used in conjunction with the analytic results to develop empirical expressions for stress field and energy as functions of aspect ratio, which are somewhat insensitive to other features of the geometry. The analyses are used to assess the effect of lattice mismatch, dot volume and dot/surface contact area on the induced stresses and elastic energies. Furthermore, the interaction energy between surface islands is determined by finite element analyses. Outputs from these analyses are then used in an optimization of several cases of ordering of islands. The results show that for a range of idealized geometries, the shape of the surface island has little impact on the strain energy, and thereby the interaction energy.

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Section: Introductionmentioning

confidence: 99%

Elastic fields and energies of coherent surface islands

Jónsdóttir

Halldorsson

Beltz

et al. 2006

Modelling Simul. Mater. Sci. Eng.

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“…15 In this growth mode, a first layer of seed QDs is formed, followed by a short period GaAs/InAs superlattice ͑SL͒, with a growth interruption after each InAs layer. The in-plane strain distribution created by the first QD layer favors In incorporation on top of QDs, 16 thereby resulting in an In-rich column-shaped nanostructure. According to the calculation based on the elastic continuum theory for the strain distribution and the eight-band k ϫ p theory for the electronic structures, 17 enhanced HH-LH mixing because of a reduction of the biaxial strain in the central portion of the CQDs.…”

Section: Introductionmentioning

confidence: 99%

Growth and characterization of InAs columnar quantum dots on GaAs substrate

Patriarche

Rossetti

et al. 2007

Journal of Applied Physics

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The growth of InAs columnar quantum dots (CQDs) on GaAs substrates by molecular beam epitaxy was investigated. The CQDs were formed by depositing a 1.8 monolayer (ML) InAs seed dot layer and a short period GaAs/InAs superlattice (SL). It was found that the growth of the CQDs is very sensitive to growth interruption (GI) and growth temperature. Both longer GI and higher growth temperature impact the size dispersion of the CQDs, which causes the broadening of photoluminescence (PL) spectrum and the presence of the additional PL peak tails. By properly choosing the GI and the growth temperature, CQDs including GaAs (3 ML)/InAs (0.62 ML) SL with period number up to 35 without plastic relaxation were grown. The corresponding equivalent thickness of the SL is 41 nm which is two times higher than the theoretical critical thickness of the strained InGaAs layer with the same average In composition of 16%. The increase of the critical thickness is partially associated with the formation of the CQDs. Based on a five-stack CQD active region, laser diodes emitting around 1120 nm at room temperature were demonstrated, indicating a high material quality. CQDs with nearly isotropic cross section (20 nm×20 nm dimensions) were formed by depositing a 16-period GaAs (3 ML)/InAs (0.62 ML) SL on an InAs seed dot layer, indicating the feasibility of artificial shape engineering of QDs. Such a structure is expected to be very promising for polarization insensitive device applications, such as semiconductor optical amplifiers.

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“…For self-assembled nanostructures, the size homogeneity and spatial distribution can be greatly improved by stacking several layers. [1][2][3][4] In this context, the vertical stacks of self-assembled InAs quantum wires ͑QWRs͒ grown on InP͑001͒ are of particular interest for lasers, as they emit light at 1.30 and 1.55 m. [5][6][7] In stacks of nanostructures, the buried ones produce inhomogeneous strain fields that propagate toward the capping layer surface where the next nanostructures will be formed. 1,2 This leads to a vertical correlation between the nanostructures layers depending both on the size of the buried nanostructures and the spacer layer thickness.…”

mentioning

confidence: 99%

Stacking of InAs/InP(001) quantum wires studied by in situ stress measurements: Role of inhomogeneous stress fields

Fuster¹,

González²,

González³

et al. 2004

Applied Physics Letters

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Size and spatial distribution homogeneity of nanostructures is greatly improved by making stacks of nanostructures separated by thin spacers. In this work, we present in situ and in real time stress measurements and reflection high-energy electron diffraction observations and ex situ transmission electron microscopy ͑TEM͒ characterization of stacked layers of InAs quantum wires ͑QWRs͒ separated by InP spacer layers, d(InP), of thickness between 3 and 20 nm. For d(InP)Ͻ20 nm, the amount of InAs involved in the created QWR from the second stack layer on, exceeds that provided by the In cell. Our results suggest that in those cases InAs three dimensional islands formation starts at the P/As switching and lasts during further InAs deposition. We propose an explanation for this process that is strongly supported on TEM observations. The results obtained in this work imply that concepts like the existence of a critical thickness for two-to three-dimensional growth mode transition should be revised in correlated QWR stacks of layers. © 2004 American Institute of Physics. ͓DOI: 10.1063/1.1759374͔The incorporation of nanostructures in electronic and optoelectronic devices provides properties improvement and design possibilities, yet requiring the control of their size and position. For self-assembled nanostructures, the size homogeneity and spatial distribution can be greatly improved by stacking several layers. [1][2][3][4] In this context, the vertical stacks of self-assembled InAs quantum wires ͑QWRs͒ grown on InP͑001͒ are of particular interest for lasers, as they emit light at 1.30 and 1.55 m. [5][6][7] In stacks of nanostructures, the buried ones produce inhomogeneous strain fields that propagate toward the capping layer surface where the next nanostructures will be formed. 1,2 This leads to a vertical correlation between the nanostructures layers depending both on the size of the buried nanostructures and the spacer layer thickness.In this work, we have studied the growth of multilayers of InAs QWRs with different spacer layer thicknesses, d(InP), by in situ and in real time stress measurements and reflection high-energy electron diffraction ͑RHEED͒. A strong influence of the spacer layer thickness on QWR formation process in the second and successive layers of the stack has been observed: QWRs are correlated for d(InP)Ͻ20 nm, where a reduction of the amount of deposited InAs necessary for QWR formation ͑observed by RHEED͒ together with an increase in InAs growth rate ͑ob-tained from stress measurements͒ take place. In order to explain these results, we propose a model that is strongly supported by transmission electron microscopy ͑TEM͒ images. Our experiments provide quantitative values of the extra amount of material involved in the formation of vertically correlated self-assembled nanostructures, as well as the evidence of the absence of a two-dimensional ͑2D͒-threedimensional ͑3D͒ growth mode transition as the relevant process in nanostructures self-assembling during stacking.The samples under study consist of...

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Vertically Self-Organized InAs Quantum Box Islands on GaAs(100)

Cited by 1,359 publications

References 14 publications

Elastic fields and energies of coherent surface islands

Elastic fields and energies of coherent surface islands

Growth and characterization of InAs columnar quantum dots on GaAs substrate

Stacking of InAs/InP(001) quantum wires studied by in situ stress measurements: Role of inhomogeneous stress fields

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