Strain-controlled correlation effects in self-assembled quantum dot stacks

Kunert, R.; Schöll, Eckehard

doi:10.1063/1.2354476

Cited by 11 publications

(4 citation statements)

References 18 publications

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“…Apart from the site, the size of the buried islands, elastic anisotropy of the spacer material, the growth direction, corrugated surface morphologies, and the modulation of the chemical composition of the spacer material influence the subsequent nucleation. [11][12][13][14][15] However, despite the fact that elastic interactions favor lateral ordering of islands as well, they turned out to be rather weak 16 and only rather short-range ordering was observed in the above mentioned systems by atomic force microscopy, transmission electron microscopy, and x-ray diffraction ͑XRD͒. [16][17][18][19][20][21] Apart from vertical island ordering in columnar form, in III-V, 22,23 II-VI, [24][25][26] and IV-VI compounds 27 also oblique ordering was observed, 28 typically for larger spacer layer thicknesses, before for sufficiently wide spacers the ordering finally vanishes.…”

Section: Introductionmentioning

confidence: 99%

X-ray diffraction investigation of a three-dimensional Si/SiGe quantum dot crystal

et al. 2009

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High-resolution x-ray diffraction was employed to study the structural properties of a three-dimensional periodic arrangement of SiGe quantum dots in a Si matrix. Using extreme ultraviolet lithography at a synchrotron source a two-dimensional array of pits ͑period 90ϫ 100 nm 2 ͒ was defined and transferred into a ͑001͒ Si wafer by reactive ion etching. By molecular-beam epitaxy SiGe islands of about 30 nm diameter and 3 nm height were grown into the pits. Subsequent deposition of Si spacer layers of 10 nm thickness and SiGe island layers results in a three-dimensionally periodic arrangement of quantum dots, mediated by the strain fields of the buried dots. Their so far unmatched structural perfection is assessed by coplanar x-ray diffractometry using synchrotron radiation. Reciprocal-space maps around the ͑004͒ and ͑224͒ reciprocal-lattice maps were recorded and analyzed to get quantitative information on the disorder of the dot positions and to obtain the mean Ge content of the dots. In addition, information on the strain fields was deduced from the analysis of the diffraction data. Together with atomic force microscopy data on the island shape and size distribution, a complete structural characterization is achieved.

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Section: Introductionmentioning

confidence: 99%

X-ray diffraction investigation of a three-dimensional Si/SiGe quantum dot crystal

et al. 2009

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“…However, other parameters such as the specific shape of the QDs [4,29], the elastic anisotropy of the material [4,28,29] or the spacer layer thickness [4,28] need to be considered as well to predict the vertical distribution of the QDs. Understanding these complex systems needs both a strong theoretical model and precise experimental measurements to compare the obtained results.…”

Section: Resultsmentioning

confidence: 99%

Analysis of the 3D distribution of stacked self-assembled quantum dots by electron tomography

et al. 2012

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The 3D distribution of self-assembled stacked quantum dots (QDs) is a key parameter to obtain the highest performance in a variety of optoelectronic devices. In this work, we have measured this distribution in 3D using a combined procedure of needle-shaped specimen preparation and electron tomography. We show that conventional 2D measurements of the distribution of QDs are not reliable, and only 3D analysis allows an accurate correlation between the growth design and the structural characteristics.

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“…In this case, one should expect that the buried island shape still influences the strain distribution map on top of the GaAs spacer layer. Thus the cluster formation can be an indication that the periodic stress field profile on the GaAs spacer surface is more complex[33][34][35] than those usually assumed in the literature; the strain profile on the spacer surface is characterized by a single minimum above the buried island center. As a consequence, surface islands nucleate above the buried islands, forming the vertically aligned stacks observed in previous experiments[18,22,26,27].…”

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confidence: 89%

Designing spatial correlation of quantum dots: towards self-assembled three-dimensional structures

Bortoleto¹,

Zelcovit

Gutiérrez³

et al. 2007

Nanotechnology

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Buried two-dimensional arrays of InP dots were used as a template for the lateral ordering of self-assembled quantum dots. The template strain field can laterally organize compressive (InAs) as well as tensile (GaP) self-assembled nanostructures in a highly ordered square lattice. High-resolution transmission electron microscopy measurements show that the InAs dots are vertically correlated to the InP template, while the GaP dots are vertically anti-correlated, nucleating in the position between two buried InP dots. Finite InP dot size effects are observed to originate InAs clustering but do not affect GaP dot nucleation. The possibility of bilayer formation with different vertical correlations suggests a new path for obtaining three-dimensional pseudocrystals.

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Strain-controlled correlation effects in self-assembled quantum dot stacks

Cited by 11 publications

References 18 publications

X-ray diffraction investigation of a three-dimensional Si/SiGe quantum dot crystal

X-ray diffraction investigation of a three-dimensional Si/SiGe quantum dot crystal

Analysis of the 3D distribution of stacked self-assembled quantum dots by electron tomography

Designing spatial correlation of quantum dots: towards self-assembled three-dimensional structures

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