Strain field determination in III–V heteroepitaxy coupling finite elements with experimental and theoretical techniques at the nanoscale

2017 ◽  
Vol 26 (1-2) ◽  
pp. 1-8
Author(s):  
Nikoletta Florini ◽  
George P. Dimitrakopulos ◽  
Joseph Kioseoglou ◽  
Nikos T. Pelekanos ◽  
Thomas Kehagias
Keyword(s):  
Finite Elements ◽  
Strain Field ◽  
Strain Distribution ◽  
Elastic Strain ◽  
Growth Direction ◽  
Current Status ◽  
Interface Plane ◽  
Fe Method ◽  
Semiconductor Nanostructure

AbstractWe are briefly reviewing the current status of elastic strain field determination in III–V heteroepitaxial nanostructures, linking finite elements (FE) calculations with quantitative nanoscale imaging and atomistic calculation techniques. III–V semiconductor nanostructure systems of various dimensions are evaluated in terms of their importance in photonic and microelectronic devices. As elastic strain distribution inside nano-heterostructures has a significant impact on the alloy composition, and thus their electronic properties, it is important to accurately map its components both at the interface plane and along the growth direction. Therefore, we focus on the determination of the stress-strain fields in III–V heteroepitaxial nanostructures by experimental and theoretical methods with emphasis on the numerical FE method by means of anisotropic continuum elasticity (CE) approximation. Subsequently, we present our contribution to the field by coupling FE simulations on InAs quantum dots (QDs) grown on (211)B GaAs substrate, either uncapped or buried, and GaAs/AlGaAs core-shell nanowires (NWs) grown on (111) Si, with quantitative high-resolution transmission electron microscopy (HRTEM) methods and atomistic molecular dynamics (MD) calculations. Full determination of the elastic strain distribution can be exploited for band gap tailoring of the heterostructures by controlling the content of the active elements, and thus influence the emitted radiation.

Determination of the lattice translation across {110} APBs in GaAs

1988 ◽  
Vol 46 ◽  
pp. 600-601
Author(s):  
D.R. Rasmussen ◽  
N.-H. Cho ◽  
C.B. Carter
Keyword(s):  
Grain Boundaries ◽  
Lower Energy ◽  
Antiphase Boundary ◽  
The Other ◽  
Boundary Structure ◽  
Interface Plane ◽  
Inversion Symmetry ◽  
High Angle ◽  
Equilibrium Distance

Domains in GaAs can exist which are related to one another by the inversion symmetry, i.e., the sites of gallium and arsenic in one domain are interchanged in the other domain. The boundary between these two different domains is known as an antiphase boundary [1], In the terminology used to describe grain boundaries, the grains on either side of this boundary can be regarded as being Σ=1-related. For the {110} interface plane, in particular, there are equal numbers of GaGa and As-As anti-site bonds across the interface. The equilibrium distance between two atoms of the same kind crossing the boundary is expected to be different from the length of normal GaAs bonds in the bulk. Therefore, the relative position of each grain on either side of an APB may be translated such that the boundary can have a lower energy situation. This translation does not affect the perfect Σ=1 coincidence site relationship. Such a lattice translation is expected for all high-angle grain boundaries as a way of relaxation of the boundary structure.

Strain analysis with nanometer resolution using a conventional transmission electron microsopy technique: electron diffraction contrast imaging revisited

1995 ◽  
Vol 53 ◽  
pp. 168-169
Author(s):  
Koenraad G F Janssens ◽  
Omer Van der Biest ◽  
Jan Vanhellemont ◽  
Herman E Maes ◽  
Robert Hull
Keyword(s):  
Electron Diffraction ◽  
Strain Field ◽  
Elastic Strain ◽  
Strain Analysis ◽  
Local Strain ◽  
Contrast Imaging ◽  
Strain Characterization ◽  
Physical Mechanisms ◽  
Diffraction Contrast ◽  
Transmission Electron

There is a growing need for elastic strain characterization techniques with submicrometer resolution in several engineering technologies. In advanced material science and engineering the quantitative knowledge of elastic strain, e.g. at small particles or fibers in reinforced composite materials, can lead to a better understanding of the underlying physical mechanisms and thus to an optimization of material production processes. In advanced semiconductor processing and technology, the current size of micro-electronic devices requires an increasing effort in the analysis and characterization of localized strain. More than 30 years have passed since electron diffraction contrast imaging (EDCI) was used for the first time to analyse the local strain field in and around small coherent precipitates1. In later stages the same technique was used to identify straight dislocations by simulating the EDCI contrast resulting from the strain field of a dislocation and comparing it with experimental observations. Since then the technique was developed further by a small number of researchers, most of whom programmed their own dedicated algorithms to solve the problem of EDCI image simulation for the particular problem they were studying at the time.

Assessment of Sylphons Lifetime

2008 ◽  
Vol 59 (5) ◽  
pp. 605-610
Author(s):  
Alexandru Pupazescu ◽  
Stefan Minoiu ◽  
Constantin Manea
Keyword(s):  
Elevated Temperature ◽  
Strain Distribution ◽  
Accurate Determination ◽  
Multiaxial Fatigue ◽  
Tensile Curve

The paper contains an assessment of the sylphons lifetime for multiaxial fatigue. Three criteria were used two based on s � N diagram and one based on energy. For a more accurate determination of the sylphons lifetime the stress and the strain distribution been determined using FEM, the tensile curve of the steel W 4541 at elevated temperature.

scholarly journals Special Finite Elements with Adaptive Strain Field on the Example of One-Dimensional Elements

2021 ◽  
Vol 11 (2) ◽  
pp. 609
Author(s):  
Tadeusz Chyży ◽  
Monika Mackiewicz
Keyword(s):  
Finite Elements ◽  
Strain Field ◽  
Main Idea ◽  
Deformation Field ◽  
Geometrical Parameters ◽  
Single Element ◽  
One Dimensional ◽  
New Type ◽  
Self Adaptation ◽  
Adaptation Method

The conception of special finite elements called multi-area elements for the analysis of structures with different stiffness areas has been presented in the paper. A new type of finite element has been determined in order to perform analyses and calculations of heterogeneous, multi-coherent, and layered structures using fewer finite elements and it provides proper accuracy of the results. The main advantage of the presented special multi-area elements is the possibility that areas of the structure with different stiffness and geometrical parameters can be described by single element integrated in subdivisions (sub-areas). The formulation of such elements has been presented with the example of one-dimensional elements. The main idea of developed elements is the assumption that the deformation field inside the element is dependent on its geometry and stiffness distribution. The deformation field can be changed and adjusted during the calculation process that is why such elements can be treated as self-adaptive. The application of the self-adaptation method on strain field should simplify the analysis of complex non-linear problems and increase their accuracy. In order to confirm the correctness of the established assumptions, comparative analyses have been carried out and potential areas of application have been indicated.

Laser interferometric method for determination of elastoplastic strain field

2003 ◽  
Author(s):  
Shibin Wang ◽  
Jingwei Tong ◽  
Mario Cottron ◽  
Linan Li ◽  
Zhiyong Wang
Keyword(s):  
Strain Field ◽  
Elastoplastic Strain ◽  
Interferometric Method ◽  
Laser Interferometric

scholarly journals Bioanalysis of small-molecule drugs in nasal and paranasal tissues and secretions: Current status and perspectives

2012 ◽  
Vol 10 (3) ◽  
pp. 686-702
Author(s):  
Ana Serralheiro ◽  
Gilberto Alves ◽  
Amílcar Falcão
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Small Molecule ◽  
Intranasal Administration ◽  
Quantitative Measurement ◽  
Current Status ◽  
Small Molecule Drugs ◽  
Development And Validation ◽  
Liquid Chromatographic

AbstractOver the last years, interest in intranasal administration as an alternative and promising route for the delivery of drugs withlocal, systemic, and even central nervous system action has tremendously increased. Accordingly, understanding of the propertiesand characteristics of the nasal cavity as well as the biodisposition processes of drugs into the nasal compartments is acquiringa significant prominence in the field of pharmacology. In this context, the development and validation of bioanalytical methodologies for the quantitative measurement of drugs and their metabolites in nasal and paranasal tissues and/or secretions is of the utmostimportance. However, currently, information concerning bioanalysis of drugs in nasal and paranasal tissues and/or secretionsis scattered. This review aims to provide a valuable overview of the methodologies that have been used for the collectionand preparation of nasal and paranasal samples with special emphasis placed on the review of liquid chromatographic methodsemployed for the quantitative determination of small-molecule drugs and their metabolites in such specimens.

Determination of residual stresses in disk keyways by the finite-elements method

1982 ◽  
Vol 14 (7) ◽  
pp. 865-867
Author(s):  
B. A. Kravchenko ◽  
V. G. Fokin ◽  
G. N. Gutman
Keyword(s):  
Finite Elements ◽  
Residual Stresses ◽  
Finite Elements Method

scholarly journals Detection of Tree Roots in an Urban Area with the Use of Ground Penetrating Radar

2016 ◽  
Vol 17 (4) ◽  
pp. 362-370 ◽  
Author(s):  
Alexander Krainyukov ◽  
Igor Lyaksa
Keyword(s):  
Urban Area ◽  
Ground Penetrating Radar ◽  
Growth Direction ◽  
Technical Condition ◽  
Tree Roots ◽  
Secondary Processing ◽  
Non Invasive ◽  
Ground Penetrating ◽  
The Given

Abstract The paper is devoted to using ground penetrating radar (GPR) for the detection of tree roots in an urban area, since GPR allow detect the hidden objects in non invasive way. It is necessary exactly to know the growth direction, thickness and depth of the roots of the tree to confidently assert about the tree root influence on the technical condition of engineering objects and structures: of the buildings, of pavements, of roadway, of engineering communications and etc. The aim of the given research was experimentally to evaluation the possibilities of detection of tree roots in an urban area with the use of GPR on frequency 400 MHz and of algorithms of secondary processing of GPR signals. Results of interpretation of radar profile and evacuation of soil around tree show the possibility of detection of the tree roots and the determination of their parameters using one or two radar concentric profiles.

Application of Moire Methods to the Determination of Transient Stress and Strain Distributions

1962 ◽  
Vol 29 (1) ◽  
pp. 23-29 ◽  
Author(s):  
W. F. Riley ◽  
A. J. Durelli
Keyword(s):  
Strain Distribution ◽  
Stress And Strain ◽  
Two Dimensional ◽  
Distribution Problem ◽  
Principal Stresses ◽  
Transient Stress ◽  
Optical Phenomenon ◽  
Moiré Effect ◽  
Fringe Patterns

When two arrays of lines are superimposed an optical phenomenon known as the moire effect is observed under certain conditions. This moire effect is used by the authors to determine the distribution of transient strains on the surface of two-dimensional bodies. The method can be used to solve completely the strain-distribution problem or it can be used in combination with photoelasticity to separate the principal stresses. The methods used in interpreting the moire fringe patterns and the techniques used to produce the patterns are described in the paper. Two applications are discussed.

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