Investigation of Nitride Semiconductor Nanostructures with Transmission Electron Microscopy PDF Download
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Author: 李仁宏
Publisher:
ISBN:
Category :
Languages : en
Pages : 117
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Book Description
Author: 李仁宏
Publisher:
ISBN:
Category :
Languages : en
Pages : 117
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Book Description
Author: Maxim Korytov
Publisher:
ISBN:
Category :
Languages : en
Pages : 180
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Book Description
The theoretical part of this thesis is dedicated to the adaptation of high-resolution transmission electron microscopy (HRTEM) for the study of GaN-based materials. First, the principle of heterostructure composition evaluation by means of the relative atomic displacement measurement is stated. The comparison of two strain measurement techniques, geometric phase analysis and projection method, is then presented. Finally, the effects of acquisition conditions on strain measurements were studied. The experimental part of this thesis is dedicated to the characterization of GaN quantum dots (QDs) realized on Al0.5Ga0.5N templates. This study revealed several phenomena original for nitride semiconductors. The surface QD shape changes from perfect pyramidal to truncated pyramidal with the increase of the nominal thickness of the deposited GaN layer. The capping of QDs having a perfect pyramidal shape leads to a QD shape truncation and a QD volume increase. Moreover, a phase separation was found in the AlGaN barriers with Al-rich zones formed above the QDs and Ga-rich regions placed around the Al-rich zones. The Al concentration into the Al-rich zones is about 70% and it decreases as the distance from the QD increases. To explain the observed phenomena, various models founded on the principle of total energy minimization have been developed. Several approaches, based on the results of this study and aimed for the improvement of the optoelectronic devices properties, are proposed.
Author: 張文明
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Andreas Rosenauer
Publisher: Springer
ISBN: 3540364072
Category : Science
Languages : en
Pages : 238
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Book Description
This book provides tools well suited for the quantitative investigation of semiconductor electron microscopy. These tools allow for the accurate determination of the composition of ternary semiconductor nanostructures with a spatial resolution at near atomic scales. The book focuses on new methods including strain state analysis as well as evaluation of the composition via the lattice fringe analysis (CELFA) technique. The basics of these procedures as well as their advantages, drawbacks and sources of error are all discussed. The techniques are applied to quantum wells and dots in order to give insight into kinetic growth effects such as segregation and migration. In the first part of the book the fundamentals of transmission electron microscopy are provided. These are needed for an understanding of the digital image analysis techniques described in the second part of the book. There the reader will find information on different methods of composition determination. The third part of the book focuses on applications such as composition determination in InGaAs Stranski--Krastanov quantum dots. Finally it is shown how an improvement in the precision of the composition evaluation can be obtained by combining CELFA with electron holography. This is demonstrated for an AlAs/GaAs superlattice.
Author: Richard Haight
Publisher: World Scientific
ISBN: 9814322849
Category : Science
Languages : en
Pages : 346
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Book Description
As we delve more deeply into the physics and chemistry of functional materials and processes, we are inexorably driven to the nanoscale. And nowhere is the development of instrumentation and associated techniques more important to scientific progress than in the area of nanoscience. The dramatic expansion of efforts to peer into nanoscale materials and processes has made it critical to capture and summarize the cutting-edge instrumentation and techniques that have become indispensable for scientific investigation in this arena. This Handbook is a key resource developed for scientists, engineers and advanced graduate students in which eminent scientists present the forefront of instrumentation and techniques for the study of structural, optical and electronic properties of semiconductor nanostructures.
Author: Giovanni Agostini
Publisher: Elsevier
ISBN: 0080558151
Category : Science
Languages : en
Pages : 501
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Book Description
In the last couple of decades, high-performance electronic and optoelectronic devices based on semiconductor heterostructures have been required to obtain increasingly strict and well-defined performances, needing a detailed control, at the atomic level, of the structural composition of the buried interfaces. This goal has been achieved by an improvement of the epitaxial growth techniques and by the parallel use of increasingly sophisticated characterization techniques and of refined theoretical models based on ab initio approaches. This book deals with description of both characterization techniques and theoretical models needed to understand and predict the structural and electronic properties of semiconductor heterostructures and nanostructures. Comprehensive collection of the most powerful characterization techniques for semiconductor heterostructures and nanostructures Most of the chapters are authored by scientists that are among the top 10 worldwide in publication ranking of the specific field Each chapter starts with a didactic introduction on the technique The second part of each chapter deals with a selection of top examples highlighting the power of the specific technique to analyze the properties of semiconductors
Author: Korytov-M
Publisher: Omn.Univ.Europ.
ISBN: 9786131545009
Category : Literary Criticism
Languages : en
Pages : 196
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Book Description
The theoretical part of this work is dedicated to the adaptation of high-resolution transmission electron microscopy for studying III-nitride semiconductors. First, the principle of heterostructure composition evaluation by means of atomic displacement measurement is stated. The comparison of two strain measurement techniques, geometric phase analysis and projection method, is then presented. Finally, the effects of acquisition conditions on the strain measurements were elaborated. The experimental part of this work is dedicated to the characterization of GaN quantum dots (QDs) grown on AlGaN templates. This study revealed several phenomena original for nitride semiconductors. The surface QD shape depends on the GaN layer thickness, whereas the buried QD shape and volume are influenced by the QD capping. Moreover, a phase separation occurs in the AlGaN barriers. To explain the observed phenomena, various models founded on the principle of total energy minimization have been developed. Several approaches, based on the results of this study and aimed for the improvement of the optoelectronic devices properties, are also proposed.
Author: Andreas Rosenauer
Publisher:
ISBN: 9783662146170
Category :
Languages : en
Pages : 256
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Author: Eirini Sarigiannidou
Publisher:
ISBN:
Category :
Languages : en
Pages : 212
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Book Description
In this thesis we present the structural characterization of GaN/AIN quantum wells (QWs) and quantum dots (QDs) grown by plasma assisted molecular beam epitaxy. The technique we use is the transmission electron microscopy in (i) high resolution, (ii) energy filtered, (Hi) conventional and (iv) convergent beam modes. The quantitative analysis of our nanostructures is realized using a projection method and the geometric phase analysis. In order to obtain the most accurate results those methods are optimized and specific experimental conditions, like off-axis HRTEM images, are applied. A comparison study between a Ga-face and a N-face GaN/AIN superlattice (SL) is presented and the higher structural quality (the Ga-face SL is proven: abrupt and uniform interfaces, absence of inversion domain boundaries and partially strained QWs. We also analyze the effects of AIN overgrowth on the structural quality of GaN nanostructures. We show that the overgrowth process implies a thinning of the GaN QWs and an isotropic reduction of the GaN QDs size. The phenomenon is attributed to an exchange mechanism between AI atoms from the cap layer and Ga atoms in the nanostructures. We investigate the strain distribution in a GaN/AIN QD superlattice. Using HRTEM, theoretical calculations and X-ray diffraction experiments we demonstrate that the vertical alignment of the QDs is due to a modulation of the strain state of the AIN layers. Finally, we examine the polytype conversion of a GaN film from N-face wurtzite to zinc-blende structure due to Mg high doping.
Author: Challa S.S.R. Kumar
Publisher: Springer Science & Business Media
ISBN: 3642389341
Category : Science
Languages : en
Pages : 718
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Book Description
Third volume of a 40volume series on nanoscience and nanotechnology, edited by the renowned scientist Challa S.S.R. Kumar. This handbook gives a comprehensive overview about Transmission electron microscopy characterization of nanomaterials. Modern applications and state-of-the-art techniques are covered and make this volume an essential reading for research scientists in academia and industry.
