Local Stress in Highly Strained Coherent InGaAs Islands

Kret, S.; Delamarre, C.; Laval, J. Y.; Dubon, A.

doi:10.4028/www.scientific.net/msf.294-296.649

Cited by 5 publications

(10 citation statements)

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“…DALI was used to characterise ZnSe x Te 1--x /ZnSe multi-quantum wells [59], and to investigated diffusion of Cd in CdSe/ZnSe [60], as well as the relaxation of strain in Ga 0.4 In 0.6 As islands grown on GaAs [61]. Kret et al [62] used a two-dimensional mapping of the distortion in a GaAs/InGaAs coherent island coupled with finite element calculations to determine the distribution of indium in the island.…”

Section: Overviewmentioning

confidence: 99%

“…Rosenauer et al [49] used Wiener filters with the local noise level estimation in Fourier space before maximum localisation. Kret et al [62] proposed to reduce the noise in two steps: (i) start by using a parameterised Wiener type of filter in Fourier space, in order to reduce the effect of global averaging of information introduced by this type of filter;…”

Section: Noise Reductionmentioning

confidence: 99%

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Extracting Quantitative Information from High Resolution Electron Microscopy

Kret

Ruterana

Rosenauer

et al. 2001

phys. stat. sol. (b)

120

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Despite the development of high-resolution electron microscopy (HREM) that allows imaging of most materials, the extraction of quantitative information at atomic scale still requires considerable additional efforts. This review presents the recent developments on techniques that can be used to determine the local strain, chemical composition or atomic structure retrieval in HREM. The source of noise in images and effective methods for improving the signal-to-noise ratio in direct or Fourier space are discussed. The artefacts of filtering are commented. In all the methods, the sample thickness has to be determined. A detailed analysis of the thin foil relaxation effect on the measured distortion fields is presented as well as the possibilities of using finite element calculations for its modelling. The local composition measurement based on the chemically sensitive reflections; pattern recognition and the measurement of lattice parameters are described. Examples from semiconductor heterostructures are discussed. The current state of the strategies used for the retrieval of the atomic configuration of defects from HRTEM images is briefly presented. The limits of detection and the accuracy of the methods are summarised; and it is pointed out that electron holography, focal series reconstruction and the coming Cs corrected microscopes will help to obtain this information with better accuracy. Content

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Section: Overviewmentioning

confidence: 99%

Section: Noise Reductionmentioning

confidence: 99%

Extracting Quantitative Information from High Resolution Electron Microscopy

Kret

Ruterana

Rosenauer

et al. 2001

phys. stat. sol. (b)

120

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“…The first proof comes from the transmission electron microscopy studies of specially designed trapezoidal QW structures. Kret et al [14] analyzed the inter-atomic distance averaged in the direction perpendicular to the growth axis and concluded that the composition in the region f its nominally linear increase in reality also changes, within experimental error, linearly. The second confirmation of the precise shape modeling is provided by the magnetooptical studies f parabolic QWs and will be discussed later in this article.…”

Section: Quantum Well Structures With Composition Profiling In the Grmentioning

confidence: 99%

Graded Quantum Well Structures Made of Diluted Magnetic Semiconductors

et al. 1998

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In this paper we review results of studies of two types of spatially graded quantum well structures containing various layers of diłuted magnetic semiconductors Cd1-x xMn xTe or Cd1-x-yMnxΜgyΤe. The design of the structures has been recently proposed by us and suitable samples have been grown by a modified molecular beam epitaxy method. In the structures of the first type a digital profiling of the composition of the constituent material in the growth direction aIlowed to produce quantum wells with a specifically required shape of the confining potential (including parabolic, half-parabolic, triangular, and trapezoidal). Such samples were used for (i) determination of the conduction and vałence band offsets in MnTe/CdTe and MgTe/CdTe systems, (ii) for the demonstration of an enhanced exciton binding in a parabolic confining potential as well as for (iii) demonstration of the possibility of "spin-splitting engineering" in diluted magnetic semiconductors quantum structures. In the second type of the structures, a precise in-plane profiling of either quantum well width or the barrier width or n-type doping intensity was realized. These structures were subsequently used for studies of the evolution of optical spectra with an increase in the concentration of confined two-dimensional gas of conduction electrons.

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“…The conditions, for which the maxima of intensities represent effectively the {110} projection of the atomic structure and preserves exactly the interatomic distances, have been described previously [7,9]. On the other hand, as far as the "geometric phase method" is concerned, Plamann et al [10] have shown that for centro-symmetrical structures, astigmatism and changes in thickness do not influence the values of displacements.…”

Section: Introductionmentioning

confidence: 99%

“…The template and deformed lattice were built up with a common origin and the displacement field was calculated at each experimental lattice point. A continuous field was then obtained by projection on a rectangular grid via interpolation and averaging with nearest neighbours [7]. Experimental strain maps were deduced by derivation.…”

Section: Introductionmentioning

confidence: 99%