Uniform and ordered self-assembled Ge dots on patterned Si substrates with selectively epitaxial growth technique

Jin, Geng Bang; Wan, Jun; Liu, J.L.; Wang, K.L.

doi:10.1016/s0022-0248(01)00996-4

Cited by 16 publications

(10 citation statements)

References 24 publications

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“…With regard to the InAs/ GaAs systems, such experimental studies have been performed with square mesas as well as with mesas of the stripe geometry. 15, the experimental results reported show that island formation occurs near the convex geometry features, while the concave edges do not favor the islanding. 10 Similar studies have been recently performed for the Ge/ Si systems.…”

Section: Island Formation and Organization On The Patterned Substrmentioning

confidence: 82%

“…We note that there is an important similarity between the multilayered QD structure formation and the growth on nanoscale mesas. 15, and discussion in the text). 4), and the compressive stress in the center of the system relaxes towards the Ge overlayer facets substantially, with degree of this relaxation being dependent on the Ge overlayer number and details of the mesa geometry.…”

Section: Island Formation and Organization On The Patterned Substrmentioning

confidence: 91%

“…1 As extensive experimental studies involving growth on micron size mesas have unambiguously shown, in the course of heteroepitaxy on the nonplanar substrates, there exist preferential places on the mesas for islands to form (i.e., a preferential islanding takes place). 14,15 This observation suggests that there is a particular hierarchy of the regions, where the self-organization of islands takes place. 1, 6,9 The islanding on the micron size stripe GaAs mesas has been shown to occur preferably in the stripe mesa center.…”

Section: Island Formation and Organization On The Patterned Substrmentioning

confidence: 95%

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Atomic scale stresses and strains in Ge∕Si(001) nanopixels: An atomistic simulation study

Makeev

Madhukar

2004

Journal of Applied Physics

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Control of nanocrystal surface defects for efficient charge extraction in polymer-ZnO photovoltaic systems J. Appl. Phys. 112, 066103 (2012) Experimental surface-enhanced Raman scattering response of two-dimensional finite arrays of gold nanopatches Appl. Phys. Lett. 101, 111606 (2012) Nano-hillock formation in diamond-like carbon induced by swift heavy projectiles in the electronic stopping regime: Experiments and atomistic simulations Appl. Phys. Lett. 101, 113115 (2012) Mass transport and thermal stability of TiN/Al2O3/InGaAs nanofilms Recent progress in the growth of nanostructures on nonplanar (patterned) substrates has brought to the forefront issues related to atomic-level surface and subsurface stress and strain field variations, as these govern the process of formation of such nanostructures and strongly affect their physical properties. In this work, we use atomistic simulations to study the atomically resolved displacements, stresses, strains, and the strain energy in laterally finite nanoscale Si͑001͒ mesas, uncovered and covered with the lattice-mismatched Ge overlayers. The spatial variations of the stress are examined both across the surface profile of the mesas and in the direction down to the substrate. We find that the hydrostatic stress and strain at the Ge/ Si interface undergo rapid changes from tensile in the interior of the Si mesa to compressive in the Ge overlayer, with the transition taking place over distances of the order of Si lattice constant. Substantial relaxation of the hydrostatic stress and strain, in both the lateral and vertical directions, is observed in the Ge overlayer, in the Si͑001͒ mesa interior, and in the substrate. Atomic displacement fields, computed in the Ge overlayer and in the Si͑001͒ mesa interior, demonstrate considerable inhomogeneity due to both finite geometry effects and the lattice-mismatched Ge overlayer-induced stresses. The maximum magnitude of displacements is as large as 0.7 Å, even in the case of uncovered Si͑001͒ mesa. Moreover, we find nonzero displacements in the Si substrate as far deep as 100 ML (monolayer) from the Ge/ Si interface, showing that a substantial degree of the misfit-induced stress accommodation occurs through relaxation in the Si͑001͒ mesa interior and the substrate. The topology of the equal displacement contours, in regions adjacent to the mesa edges and corners, is close to semielliptical. To reveal the impact of stress accommodation in the mesa interior and in the substrate, we compute the strain energies of the Ge overlayer atoms as a function of both the Si͑001͒ mesa height and the Ge overlayer thickness. We find that the normalized (per Ge atom) elastic energy of a fixed thickness overlayer decreases with increasing mesa depth. At a fixed mesa height, the Ge overlayer energy per Ge atom increases as a function of Ge overlayer thickness. In both cases, the dependencies are shown to be adequately fitted with exponential forms. The shear stresses in both bare and 16 ML thick Ge overlayer covered mesa systems show dram...

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Section: Island Formation and Organization On The Patterned Substrmentioning

confidence: 82%

Section: Island Formation and Organization On The Patterned Substrmentioning

confidence: 91%

Section: Island Formation and Organization On The Patterned Substrmentioning

confidence: 95%

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Atomic scale stresses and strains in Ge∕Si(001) nanopixels: An atomistic simulation study

Makeev

Madhukar

2004

Journal of Applied Physics

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“…In order to investigate the origin of the observed self-organization of heteroepitaxial islands along the edges of mesoscale topographical surface features [13,14,15], we have performed a series of simulations of an island on a mesa. Stress distributions and the total strain energy are calculated for islands located at different distances from the edge of a mesa, Fig.…”

Section: W10124 B) Edge Effectmentioning

confidence: 99%

“…Several methods have been proposed to achieve ordered arrangement of the quantum dots, including growth on substrates with dislocation networks [11] or stacking of successive layers of buried heteroepitaxial islands [12]. One of the most promising approaches to induce self-organization of heteroepitaxial islands is the self-assembly on patterned substrates [13,14,15]. In particular, Kamins and Williams [13] demonstrated one-dimensional ordering of Ge islands along the edges of lithographically prepared Si mesas.…”

Section: Introductionmentioning

confidence: 99%

Atomistic simulation study of misfit strain relaxation mechanisms in heteroepitaxial islands

Dongare

Zhigilei

2002

MRS Proc.

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The mechanisms of the misfit strain relaxation in heteroepitaxial islands are investigated in twodimensional molecular dynamics simulations. Stress distributions are analyzed for coherent and dislocated islands. Thermally-activated nucleation of misfit dislocations upon annealing at an elevated temperature and their motion from the edges of the islands towards the positions corresponding to the maximum strain relief is observed and related to the corresponding decrease of the total strain energy of the system. Differences between the predictions of the energy balance and force balance criteria for the appearance of misfit dislocations is discussed. Simulations of an island located at different distances form the edge of a mesa indicate that the energy of the system decreases sharply as the island position shifts toward the edge. These results suggest that there may be a region near the edge of a mesa where nucleation and growth of ordered arrays of islands is favored.

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Self-Assembled Si1-x Ge x Dots and Islands

Baribeau

Rowell

Lockwood

Nanostructure Science and Technology

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Uniform and ordered self-assembled Ge dots on patterned Si substrates with selectively epitaxial growth technique

Cited by 16 publications

References 24 publications

Atomic scale stresses and strains in Ge∕Si(001) nanopixels: An atomistic simulation study

Atomic scale stresses and strains in Ge∕Si(001) nanopixels: An atomistic simulation study

Atomistic simulation study of misfit strain relaxation mechanisms in heteroepitaxial islands

Self-Assembled Si1-x Ge x Dots and Islands

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