Step and kink energetics on GaAs(001)

Heller, Edwin J.; Zhang, Z. Y.; Lagally, M. G.

doi:10.1103/physrevlett.71.743

Cited by 80 publications

(44 citation statements)

References 14 publications

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“…First, we emphasize that most previous STM investigations have focussed on the near-equilibrium dynamics of monoatomic step edges. Above mentioned studies of ''frizziness, '' 11 and similar studies of step-edge roughness, 14,15 have elucidated both mass transport and energetics at step edges. In similar studies, the time-correlation functions describing equilibrium fluctuations of step edges have been analyzed in order to assess such mass transport processes and effective transport coefficients.…”

Section: Introductionmentioning

confidence: 99%

Evolution of far-from-equilibrium nanostructures on Ag(100) surfaces: Protrusions and indentations at extended step edges

et al. 2000

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Scanning tunneling microscopy is used to monitor the formation and relaxation of nanoprotrusions and nanoindentations at extended step edges following submonolayer deposition of Ag on Ag(100). Deposition of up to about 1/4 ML Ag produces isolated two-dimensional (2D) Ag clusters, which subsequently diffuse, collide, and coalesce with extended step edges, thus forming protrusions. Deposition of larger submonolayer amounts of Ag causes existing step edges to advance across terraces, incorporating 2D islands. The resulting irregular step structure rapidly straightens after terminating deposition, except for a few larger indentations. Relaxation of these far-from-equilibrium step-edge nanoconfigurations is monitored to determine rates for restructuring versus local geometry and feature size. This behavior is analyzed utilizing kinetic Monte Carlo simulations of an atomistic lattice-gas model for relaxation of step-edge nanostructures. In this model, mass transport is mediated by diffusion along the step edge (i.e., "periphery diffusion"). The model consistently fits observed behavior, and allows a detailed characterization of the relaxation process, including assessment of key activation energies. Scanning tunneling microscopy is used to monitor the formation and relaxation of nanoprotrusions and nanoindentations at extended step edges following submonolayer deposition of Ag on Ag͑100͒. Deposition of up to about 1/4 ML Ag produces isolated two-dimensional ͑2D͒ Ag clusters, which subsequently diffuse, collide, and coalesce with extended step edges, thus forming protrusions. Deposition of larger submonolayer amounts of Ag causes existing step edges to advance across terraces, incorporating 2D islands. The resulting irregular step structure rapidly straightens after terminating deposition, except for a few larger indentations. Relaxation of these far-from-equilibrium step-edge nanoconfigurations is monitored to determine rates for restructuring versus local geometry and feature size. This behavior is analyzed utilizing kinetic Monte Carlo simulations of an atomistic lattice-gas model for relaxation of step-edge nanostructures. In this model, mass transport is mediated by diffusion along the step edge ͑i.e., ''periphery diffusion''͒. The model consistently fits observed behavior, and allows a detailed characterization of the relaxation process, including assessment of key activation energies.

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Section: Introductionmentioning

confidence: 99%

Evolution of far-from-equilibrium nanostructures on Ag(100) surfaces: Protrusions and indentations at extended step edges

et al. 2000

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“…For a typical GaAs (100) surface, it has been well established that surface diffusion and incorporation are anisotropic [20]. With additional annealing, the material from the edges of the square holed nanostructure, tend to fill the center hole but at different rates depending on direction.…”

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confidence: 99%

Self-organization of quantum-dot pairs by high-temperature droplet epitaxy

et al. 2006

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The spontaneously formation of epitaxial GaAs quantum-dot pairs was demonstrated on an AlGaAs surface using Ga droplets as a Ga nanosource. The dot pair formation was attributed to the anisotropy of surface diffusion during high-temperature droplet epitaxy.Keywords Quantum dots AE Droplet epitaxy Self-assembly of epitaxial semiconductor nanostructures has been an intensive field of research. In particular, the Stranski-Krastanov (SK) growth mode based on the use of lattice-mismatched materials has played an important role in the formation of nanostructures, the investigation of quantum confinement effects, and has made possible applications of nanostructures [1][2][3]. While the SK growth mode has been a very powerful and beautiful technique, there has been a significant, but perhaps less well-known, parallel development using lattice matched materials as an alternative approach for the growth of nanostructures called ''droplet epitaxy '' [4-7]. Here liquid metal droplets are first formed as an intermediate growth step before being converted into semiconductor nanostructures. While the two growth approaches are very different, both the SK and the droplet approach are similar in that they both suffer from the stochastic nature of self-assembly. As a result, the control of spatial ordering of semiconductor nanostructures has been extremely challenging while desirable for applications, such as, the fabrication of quantum-dot (QD) molecules for quantum computing [8]. Consequently, there has been much recent effort to control the lateral arrangement of QDs using a range of techniques, such as, lithography [9][10][11][12], templating [13,14], and modified versions of self-organization [15][16][17][18][19]. Recently, the approach of droplet epitaxy has shown promise to the achieve local ordering of quantum nanostructures [6,7]. In this letter, we report on the use of droplet epitaxy and anisotropic surface diffusion to fabricate QD pairs.All of the samples used in this study were grown in a molecular beam epitaxy (MBE) system equipped with reflection high-energy electron diffraction (RHEED) and a highly accurate (±2°C) optical transmission thermometry system for substrate temperature determination and control. Our growth approach was to first grow a 500 nm GaAs buffer layer on a semi-insulating GaAs (100) substrate, followed by a 50 nm thick Al 0.3 Ga 0.7 As layer. This was followed by the deposition of Ga and the formation of Ga droplets at the substrate temperature of 550°C with the arsenic source fully closed. We used a valved arsenic source to provide precise and fast control for over three orders of

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“…The stability of the ͓110͔-oriented rows of Sb dimers inherent to this reconstruction gives the terrace edges their characteristically straight ͓110͔-oriented and jagged ͓110͔-oriented edges. 12 Thin GaSb films ͑8 ML͒ grown at 400°C within the superlattice have a very similar surface structure ͑atomically smooth terraces with few islands and pits͒, but with more rounded terrace edges.…”

Section: Naval Research Laboratory Washington DC 20375mentioning

confidence: 99%

Origins of interfacial disorder in GaSb/InAs superlattices

Thibado

Bennett

Twigg

et al. 1995

Applied Physics Letters

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Step and kink energetics on GaAs(001)

Cited by 80 publications

References 14 publications

Evolution of far-from-equilibrium nanostructures on Ag(100) surfaces: Protrusions and indentations at extended step edges

Evolution of far-from-equilibrium nanostructures on Ag(100) surfaces: Protrusions and indentations at extended step edges

Self-organization of quantum-dot pairs by high-temperature droplet epitaxy

Origins of interfacial disorder in GaSb/InAs superlattices

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