Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 24 for “"high resolution X-ray diffraction"”.
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GaN Epitaxy on Melt Grown Thermally Prepared Bulk ZnO Substrates
… were used as a substrate for GaN grown by MBE. High-resolution x-ray diffraction and low temperature PL results show that similar high quality GaN layers can be achieved on both annealed O-face and Zn-face ZnO substrates. The prospect of the device applications of GaN epitaxy on ZnO, including …
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Analysis of materials properties of thin film structures for thermoelectric and thermophotovoltaic applications
… and thermoelectrics respectively. High resolution x-ray diffraction (HRXRD) was used to determine the As concentration in each of the InAsP layers. Arsenic concentration was found to vary linearly with the percentage of AsH3 in the reactive gas flow up to 60 % deposited, and had an …
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An X-ray study of charge-density-wave pinning and a measurement of the thermal conductivity in blue bronze
… on pinning site density npin were determined by high-resolution X-ray diffraction. The main results are that the phase coherence volume contains many pinning sites, and that the coherence length along two of the three directions measured decreases roughly as n;i~· 4 . A functional form for the …
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Growth of Single Crystal, Metastable Ge(1-X)sn(x) Alloys and Ge(1-X)sn(x)/ge Strained-Layer Superlattices on Ge(001)2 X 1 by Molecular Beam Epitaxy
… T\sb{s}\leq140\sp\circ$C. In-situ reflection high energy electron diffraction combined with post-deposition high-resolution x-ray diffraction (HR-XRD) and XTEM results showed that the $\rm Ge\sb{1-x}Sn\sb{x}(001)2x1$ alloy and Ge(001)2x1 spacer layers were commensurate. In fact, the alloy …
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Growth and Characterization of (InGa)2O3 Alloys
… properties are conducive to improved power and high breakdown devices. The indium gallium oxide alloy makes it one of the candidates that can be used in heterostructures in which the electrical and optical properties can be tuned. While research has been concentrated on the development and …
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DISORDERING IN PYROCHLORE PHASES FOR RADIONUCLIDES DISPOSAL: A MULTISCALE STRUCTURE STUDY
… composition, in particular, has demonstrated high radiation resistance, making it an ideal host-matrix for encapsulating radioactive elements within the crystal structure. Despite the average structure, chemical composition can induce intrinsic structural distortions and control the degree of …
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Synchrotron radiation-based characterization of GaN- based MQW structures and strongly correlated materials
… to the scientific community. Synchrotron-based High Resolution X-ray Diffraction (HRXRD) was used to characterize the structural properties of GaN-based multiple quantum well (MQW) structures grown on trapezoidal shaped GaN ridges. Results where interpreted within the framework of vapor-phase …
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Characterisation of polar (0001) and non-polar (11-20) ultraviolet nitride semiconductors
… heterostructures are very inefficient due to the high lattice mismatch of these films with sapphire substrates, leading to high dislocation densities. This thesis describes the characterisation of the nanostructures of a range of UV structures, including c-plane (polar) AlGaN epilayers grown on …
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Plastic Relaxation of Highly Tensile Strained (100) Ge/InGaAs Heterostructures
… strain-enhanced characteristics. We show arrays of misfit dislocations (MDs), which are mostly disassociated, form at the and#949t-Ge/InGaAs interface for and#949t-Ge layers as thin as 15 nm with less than 1% total mismatch. Wedge geometry of plain view transmission electron microscopy …
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Indium-Gallium-Arsenide Quantum Wire Infrared Photodetectors
… superlattice (SPS) forms QWRs, with a high density of ∼1 x 10 6 cm-1, via the SILO process. The QWR characteristics were confirmed using polarized photoluminescence (PPL) and cross-sectional transmission electron microscopic (XTEM) images in structures incorporated with different …
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Phase Diagram Determination of (2-Amino-2-Methyl-1, 3-Propanediol) AMPL-TRMP (Trimethylolpropane) Binary System
… scanning calorimetry thermal analyses, high resolution x-ray diffraction structural analyses and visual inspection of the prepared binary mixtures at different temperatures. The room temperature structure of these globular organic compounds changes from an ordered monoclinic structure to …
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Characterisation of ScN and ScGaN alloys grown by Molecular Beam Epitaxy
… symmetry towards a non-polar structure at higher Sc contents, which could lead to additional device functionalities such as ferroelectric switching. However, experimental data regarding the properties of ScGaN alloys are very limited, and further investigations of the growth are required if …
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Fundamental studies of heterostructured oxide thin film electrocatalysts for oxygen reduction at high temperatures
… However, the oxide surface chemistry at high temperatures and near ambient oxygen pressure is poorly understood, which limits the design of highly active catalysts. This work investigates heterostructured interfaces between (Lai. xSrx)CoO 3-3 (where x = 0.2 and 0.4, LSC80-2011 3 and …
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Electronic structure of perovskite oxide surfaces at elevated temperatures and its correlation with oxygen reduction reactivity
… approaches, and is important for enabling high performance electrochemical energy conversion and storage systems, such as fuel cells, batteries, super-capacitors. Firstly, this thesis identified the correlation between the surface chemistry and electronic structure on SrTi1Fe,03 (STF), as a …
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Structural, Magnetic, Dielectric, and Optical Properties of DyCrO3 and GeNi2O4 Materials
… with an antiferromagnetic transition at a higher temperature. Thin films of these compounds are widely researched for their applications in spintronics. The investigation of the structural, magnetic, dielectric, and optical properties of deposited thin films of these two materials can …
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Growth and characterization of high quality relaxed graded silicon germanium layers for integrated photodetectors
… materials concerns need to be addressed-{i) a high surface roughness, (ii) the formation of dislocation pile-ups, (iii) an increase in the threading dislocation density, (iv) tensile strains and micro-cracking due to thermal mismatch, and (v) particulate contamination from germane gas phase …
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Mid-infrared antimonide based type II quantum dot lasers for use in gas sensing
… techniques including inter-facial misfit (IMF) arrays were experimented for the integration of the InSb QDs on GaAs substrates. The density of threading dislocations and the quality of the QDs were investigated using cross-sectional transmission electron microscopy (TEM) images, high resolution …
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Molecular Engineering of Dipolar and Octupolar Non-Linear Optical Materials for Next-Generation Telecommunications
… secured via in-house and synchrotron-based X-ray diffraction experiments (by proxy), which the author employed for charge density analyses. Multipolar modelling of experimental charge densities of the subject NLO materials forms an integral part of this thesis. Topological analysis is applied …
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Heteroepitaxial Germanium-on-Silicon Thin-Films for Electronic and Photovoltaic Applications
Developing high efficiency solar cells for lower manufacturing costs has been a key objective for photovoltaic researchers to drive down the levelized cost of energy for solar power. In this pursuit, III-V compound semiconductor based solar cells have steadily shown performance improvement at …
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In-situ Untersuchungen zur Entstehung von Oberflächengittern in Polymeren
In festen azobenzenhaltigen Polymeren wurde bei Bestrahlung mit blauem Licht ein makroskopischer Materialtransport beobachtet. Um die Dynamik der Gitterentstehung zu verfolgen, wurde am Speicherring für Synchrotronstrahlung ein Gitterschreibaufbau errichtet. Damit konnte erstmals in dieser Arbeit …
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