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

Bortoleto, J. R. R.; Zelcovit, João Guilherme; Gutiérrez, Humberto; Bettini, Jefferson; Cotta, M. A.

doi:10.1088/0957-4484/19/01/015601

Cited by 6 publications

(5 citation statements)

References 35 publications

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“…[1][2][3][4][5] It is very frequent that authors make a direct association of interface roughness increase with a larger emission line width ͑LW͒. However, roughness correlation between interfaces along growth direction, such as in quantum dots stacking, 15 can result in a reduction in LW even for a rougher interface. 16 This may render difficult the direct straightforward interpretation of spectra.…”

Section: Structural Versus Pl Measurementsmentioning

confidence: 99%

Heterostructure interface roughness characterization by chemical mapping: Application to InGaP/GaAs quantum wells

Tizei

Bettini

Carvalho

et al. 2008

Journal of Applied Physics

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Interface quality is an important factor for the functionality of semiconductor modern devices. Routinely, these characteristics are probed qualitatively by photoluminescence. However, quantitative microscopic structural information to corroborate models is not commonly available. Among different techniques, atomic resolution transmission electron microscopy images represent the basic experimental method to analyze the quality of buried interfaces. In this work we describe the analysis of chemical changes determined from the quantitative comparison of intensity distribution across an interface in high resolution transmission electronic microscopy ͑HRTEM͒ images. We have shown that a careful analysis of HRTEM images contrast can provide extremely useful quantitative information on interface roughness. We have characterized four different samples of InGaP/GaAs quantum wells grown with different interfacial schemes. Limits in the quantification from different sources, such as sample preparation, sampling, and statistics, have been thoroughly analyzed.

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Section: Structural Versus Pl Measurementsmentioning

confidence: 99%

Heterostructure interface roughness characterization by chemical mapping: Application to InGaP/GaAs quantum wells

Tizei

Bettini

Carvalho

et al. 2008

Journal of Applied Physics

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“…Scott, 2008; Jiang et al , 2010), physics (e.g. Bortoleto et al , 2008), chemistry techniques (e.g. Huo et al , 1997; Imhof et al , 1999) and material science (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Diatoms contribute massively to the world's primary production, cause most of the silica sedimentation in the world oceans and influence the global carbon cycle (e.g. Nelson et al, 1995;Smetacek, 1999;Brownlee & Taylor, 2001;Armbrust, 2009).…”

Section: Introductionmentioning

confidence: 99%

A new method for exact three‐dimensional reconstructions of diatom frustules

Friedrichs

Maier

Hamm

2012

Journal of Microscopy

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Key words. Confocal laser scanning microscopy (CLSM), diatom, finite element analysis, photogrammetry lightweight value, scanning electron microscopy (SEM), three-dimensional reconstruction. SummaryExact geometric description, numerical analysis and comparison of microscopic objects such as the frustules of diatoms are of increasing importance in basic research (e.g. functional morphology, taxonomy and biogeochemistry). Similarly, applied research and product development in the fields of lightweight construction and nanotechnology can benefit from machine-readable data of such structures. This paper presents a new method to combine data from scanning electron microscopy and confocal laser scanning microscopy to generate exact three-dimensional models of diatom frustules. We propose a method to obtain a high-quality mesh for subsequent analysis through finite element analysis, for example, for biomechanical research on diatom frustules. A specific lightweight value as a universal tool to describe and compare the biomechanical quality of microscopic objects is introduced.Our approach improves the precision of three-dimensional reconstructions, but the generation of usable finite element meshes from complex three-dimensional data based on microscopic techniques requires either a transformation of grid points into elements or smoothing algorithms. Biomechanical analyses of differently obtained models indicate that more complex three-dimensional reconstructions lead to more realistic results.

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“…1 Introduction Many of the strategies that have been developed to enhance the shape and size regularity of self assembled quantum dots (QDs) rely on the use of stress as the conducting force for the control of the nucleation site, size and morphology of the nanostructures [1,2]. The strain field is known to be the primary source of QD vertical alignment, and has been extensively studied in the last years by means of X-ray techniques, transmission electron microscopy, photoluminescence (PL) and Raman scattering in the case of GaN QDs [3][4][5][6][7].…”

mentioning

confidence: 99%

Depth profiling of optical and vibrational properties in GaN/AlN quantum dot superlattices

Cros

Fresneda

Budagosky

et al. 2009

Physica Status Solidi (b)

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Spatially resolved confocal μ‐Raman and μ‐photoluminescence experiments were performed to analyze the vibrational and optical properties of GaN/AlN quantum dots as a function of depth. Two approaches have been followed. First, spectra were taken by defocusing the microscope objective at various depths on the sample surface. In a second set of experiments a bevel at an angle of 20° with respect to the surface normal was prepared by mechanical polishing of the surface, and spectra were taken across the bevel. The E2h vibrational modes ascribed to the GaN QDs and the AlN spacer redshift towards the surface, indicating the progressive relaxation of the QDs and a considerable increase of the tensile strain in the AlN spacer. The photoluminescence is found to blueshift and narrow towards the surface. This behaviour is ascribed to the decrease of the QD internal electric field as a consequence of the relaxation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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

Cited by 6 publications

References 35 publications

Heterostructure interface roughness characterization by chemical mapping: Application to InGaP/GaAs quantum wells

Heterostructure interface roughness characterization by chemical mapping: Application to InGaP/GaAs quantum wells

A new method for exact three‐dimensional reconstructions of diatom frustules

Depth profiling of optical and vibrational properties in GaN/AlN quantum dot superlattices

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