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Artykuły w czasopismach na temat "Defects - Single Crystalline Oxides"
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Wittkämper, Florian, André Bikowski, Klaus Ellmer, Konrad Gärtner i Elke Wendler. "Energy-Dependent RBS Channelling Analysis of Epitaxial ZnO Layers Grown on ZnO by RF-Magnetron Sputtering". Crystals 9, nr 6 (4.06.2019): 290. http://dx.doi.org/10.3390/cryst9060290.
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The transparent conducting oxides ZnO and ZnO:Al are interesting materials for a wide range of applications. Several of these applications need a large area, single crystalline, and specially doped thin layers. A common technique for the fabrication of those layers is RF (radio frequency) -magnetron sputtering. The investigation of the crystal quality of such layers requires methods of analysis that are destruction free and that are able to obtain information about the concentration and type of defects versus depth. One such option is the Rutherford backscattering spectroscopy (RBS) in channelling mode. In this work, we exploit the channelling effect and its energy dependence, which are sensitive to the type of defects. By using appropriate software and measuring RBS channelling spectra with different beam energies, we were able to determine the depth distribution of point defects and dislocation loops. The presence of dislocation loops was proven using other previously applied analysis methods. The main advantage of RBS in channelling mode is the quantification of point defects, which can be important for defining the electrical and optical properties of such layers. The technique demonstrated is applicable to other defective crystals or thin crystalline layers.
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Trimble, L. E., G. K. Celler, D. G. Schimmel, C. Y. Lu, S. Nakahara i P. M. Fauchet. "The nature of residual stress, defects, and device characteristics for thick single-crystalline Si films on oxidized Si wafers". Journal of Materials Research 3, nr 3 (czerwiec 1988): 514–20. http://dx.doi.org/10.1557/jmr.1988.0514.
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Recently it was reported that high quality, 10–100 μm thick, single-crystalline Si films were formed on oxidized single-crystalline Si wafers by the lateral epitaxial growth over oxide (LEGO) process. Although this recrystallization process is reliable and reproducible, periodic regions of dislocations in the otherwise relatively dislocation-free Si film were not well understood. In this paper, therefore, the film stress and defect properties are investigated in detail, and devices made in recrystallized wafers are compared with devices in conventional wafer structures. Stress levels were found to be too low to cause defects, with TEM data suggesting an impurity mechanism (SiO2 precipitation) for small dislocation loops and slight crystalline misorientation for long dislocation lines in the periodic, defective areas. Device results confirmed that LEGO is a viable alternative to the dielectric isolation (DI) technology.
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Wang, Z. L., Z. W. Pan i Z. R. Dai. "Structures of Oxide Nanobelts and Nanowires". Microscopy and Microanalysis 8, nr 6 (grudzień 2002): 467–74. http://dx.doi.org/10.1017/s1431927602010383.
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We have recently reported the synthesis of one-dimensional nanobelt structures of ZnO, SnO2, In2O3, CdO, Ga2O3, and PbO2 by evaporating the desired commercial metal oxide powders at high temperatures (Science (2001), 291, 1947). The as-synthesized oxide nanobelts are pure, structurally uniform, single crystalline, and most of them free from dislocations. The beltlike morphology appears to be a unique and common structural characteristic for the family of semiconducting oxides. In the present article, we focus on the twin and stacking fault planar defects found in oxide nanobelts and nanowires although they are rarely observed. Some interesting and unique growth morphologies are presented to illustrate the roles played by surface energy and kinetics in growth. It is shown that the surfaces of the oxide nanobelts are enclosed by the low-index, low-energy crystallographic facets. The growth morphology is largely dominated by the growth kinetics.
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Nandanapalli, Koteeswara Reddy, Devika Mudusu i Sungwon Lee. "Defects-free single-crystalline zinc oxide nanostructures for efficient photoelectrochemical solar hydrogen generation". International Journal of Hydrogen Energy 45, nr 51 (październik 2020): 27279–90. http://dx.doi.org/10.1016/j.ijhydene.2020.07.138.
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Locke, Christopher, Christopher L. Frewin, Jing Wang i Stephen E. Saddow. "Growth of Single Crystal 3C-SiC(111) on a Poly-Si Seed Layer". Materials Science Forum 615-617 (marzec 2009): 157–60. http://dx.doi.org/10.4028/www.scientific.net/msf.615-617.157.
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A novel method for growing highly-crystalline 3C-SiC on an oxide release layer via a poly-Si seed layer is reported. Silicon carbide’s potential role as a ubiquitous material for MEMS fabrication lies in its dual role as an electronic and mechanical material. Unfortunately, due to residual stresses and crystal defects stemming from the large lattice constant mismatch and the thermal expansion coefficient difference between SiC and Si, the use of SiC in Si-based MEMS fabrication techniques has been very limited. The growth of 3C-SiC on a poly-Si seed layer deposited on oxide on (111)Si substrates (i.e., p-Si/ SiO2/(111)Si) provides an alternative fabrication method to expensive, traditional SOI bonding techniques for producing free-standing 3C-SiC MEMS structures. 3C-SiC grown with a poly-Si seed layer on SiO2 should experience reduced residual stress and far fewer defects due to the compliance of the SiO2 layer. Although poly-Si is utilized as a seed layer in this process, a well-ordered monocrystalline 3C-SiC layer was achieved and the process and film properties reported.
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WHITFIELD, PAMELA, i LYNDON MITCHELL. "X-RAY DIFFRACTION ANALYSIS OF NANOPARTICLES: RECENT DEVELOPMENTS, POTENTIAL PROBLEMS AND SOME SOLUTIONS". International Journal of Nanoscience 03, nr 06 (grudzień 2004): 757–63. http://dx.doi.org/10.1142/s0219581x04002620.
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Powder X-ray diffraction has become a cornerstone technique for deriving crystallite size in nanoscience due to speed and "simplicity". Unfortunately, this apparently simple technique commonly has unexpected problems. Anisotropic peak broadening related to crystallite shape, defects, and microstrain occurs frequently in nanomaterials and can significantly complicate the analysis. In some instances, the usage of the conventional single peak approach would give erroneous results, and in others, this type of analysis is not even possible. A number of different nanocrystalline oxides have been examined to determine their crystallite sizes by different techniques. They differ in terms of crystal symmetry, crystallinity, density, and present different challenges with regard to size analysis.
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Nyborg, M., Ilia Kolevatov, G. C. Vásquez, K. Bergum i E. Monakhov. "Dominant defects and carrier transport in single crystalline cuprous oxide: A new attribution of optical transitions". Journal of Applied Physics 130, nr 17 (7.11.2021): 175701. http://dx.doi.org/10.1063/5.0059406.
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Litovchenko, V. G., I. P. Lisovskyy, M. Voitovych, Andrey V. Sarikov, S. O. Zlobin, V. P. Kladko i V. Machulin. "Study of the Mechanisms of Oxygen Precipitation in RTA Annealed Cz-Si Wafers". Solid State Phenomena 156-158 (październik 2009): 279–82. http://dx.doi.org/10.4028/www.scientific.net/ssp.156-158.279.
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In this paper, the influence of the rapid thermal annealing of single crystalline Cz-Si wafers on the evolution of the concentration of interstitial oxygen as well as oxygen in precipitated oxide phase was investigated by infrared spectroscopy. The wafers were preliminary furnace annealed to create the precipitate seeds. The concentration of interstitial oxygen was shows to decrease considerably as a result of annealing during up to 40 min together with the growth of the concentration of precipitated oxygen. This effect depended on the purity and defect structure of initial wafers. The kinetic model was developed to account for the observed effects based on the modification of the solubility level for interstitial oxygen induced by defects as well as its diffusivity. Obtained results of simulation agree well with the experimental data.
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Webb, Matthew, Tao Ma, Allen H. Hunter, Sean McSherry, Jonathan Kaufman, Zihao Deng, William B. Carter i in. "Geometric defects induced by strain relaxation in thin film oxide superlattices". Journal of Applied Physics 132, nr 18 (14.11.2022): 185307. http://dx.doi.org/10.1063/5.0120176.
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Functional thin film superlattices with stability in extreme environments can lead to transformative performance in optical and thermal applications such as thermophotovoltaics. In this work, key issues associated with defects that prevent layer-by-layer growth in epitaxial, low-miscibility oxide superlattices are investigated. Layer protrusions, approximately 8 nm wide and 3 nm thick, arise from a strain relaxation mechanism in 8 nm bilayer superlattices of Ba(Zr0.5Hf0.5)O3/MgO and propagate through the subsequent superlattice layers forming an inverted pyramid structure that is spatially phase offset from the matrix. The density and size of these defects scales with the number of interfaces in the sample, indicating that surface roughness during growth is a significant factor in the formation of these defects. In situ high temperature transmission electron microscopy (1000 °C, in vacuo) measurement reveals that phase decomposition of Ba(Zr0.5Hf0.5)O3 and decoherence of the superlattice is nucleated by these defects. This work highlights that achieving optimum growth conditions is imperative to the synthesis of single-crystalline superlattices with sharp interfaces for optimized performance in extreme environments.
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Murshed, M. Mangir, Pei Zhao, Evgeny Alekseev, Ashfia Huq i Thorsten Gesing. "Lattice thermal expansion of complex oxides with intrinsic anharmonicity". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C161. http://dx.doi.org/10.1107/s2053273314098386.
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The lattice thermal expansion of crystalline solids cannot be adequately modeled by Grüneisen approximation using either Einstein single harmonic frequency or Debye frequency spectrum because a true phonon spectrum does not follow either of the two kinds. The Debye model misfits to many observations due to the fact that real solids comprises of axial anisotropy, lattice waves with dispersion at the Brillouin zone boundaries, low/high frequency optical vibrations in excess of the Debye spectrum. The actual frequency distribution is a complicated function of frequency instead of a simple parabolic Debye spectrum. The frequency distribution can be simplified using power series [1] leading to singularities before and after the Debye cutoff frequency. Using multiple Debye or Einstein oscillators, or their mixtures, is also common practice to better describe the lattice expansion, however, these models extremely suffer from intrinsic anharmonicity in particular at high temperatures. It was demonstrated that even the noble monoatomic solids required inclusion of anharmonic terms in the harmonic model to better explain the observed values [2]. Worse even, when anharmonicity becomes dominant due to formation of vacancies and defects, anomalies of hard/soft modes or change of stereochemical activities of lone electron pairs (LEPs) as function of temperature. Herein we approach an extended Grüneisen approximation that includes harmonic, quasiharmonic and intrinsic anharmonic potentials to describe the internal energy of the crystal as function of temperature. The model has been applied to several complex oxides with LEPs (Bi2Ga4O9[3]) along with axial negative thermal expansion (PbFeBO4) and rigid-unit-modes (KAsW2O9) reported here. The metric parameters were obtained from quality data collected from temperature-dependent neutron and X-ray powder diffractions.
Rozprawy doktorskie na temat "Defects - Single Crystalline Oxides"
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Dicks, Oliver A. "Computational modelling of defects and charge trapping in amorphous and crystalline metal oxides". Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10044113/.
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Thin films of metal oxides, like Al2O3 and LaAlO3, play a crucial role in emerging nanoelectronic devices. Using density functional theory (DFT) and other computational methods, the properties of defects and intrinsic polaron trapping have been calculated in LaAlO3 and amorphous Al2O3. The spectroscopic properties of neutral (Vo0) and charged (Vo+) oxygen vacancies in cubic and rhombohedral LaAlO3 have been investigated using Time Dependent DFT and the embedded cluster method. The peaks of the optical absorption spectra are predicted at 3.5 and 4.2 eV for Vo0 and 3.6 eV for Vo+ in rhombohedral LaAlO3. The calculated electron paramagnetic resonance (EPR) parameters of Vo+ accurately predict the width (3 mT) and position of its EPR spectrum. Amorphous Al2O3 is then investigated, which has applications in non-volatile memory and a-IGZO (amorphous indium-gallium-zinc oxide) thin film transistors. Amorphous Al2O3 structures were generated using a molecular dynamics melt-quench approach and found to be in good agreement with experiment. DFT calculations, using a tuned hybrid functional, determined that the a-Al2O3 band gap decreases to 5.5 eV, compared to 8.6 eV in α-Al2O3, because of the reduction in Al coordination number in the amorphous phase. This causes a shift in the electrostatic potential that lowers the conduction band minimum, adding support to experimental measurements of band offsets. Then intrinsic polaron and bipolaron trapping in a-Al2O3 is modelled. The average trapping energy of hole polarons in a-Al2O3 was calculated to be 1.26 eV, much higher than the 0.38 eV calculated for α-Al2O3. Electrons were found not to trap in both crystalline and amorphous Al2O3. To explain the negative charging of Al2O3 films the properties of oxygen, hydrogen and aluminium defects were calculated. A mechanism is proposed to explain experimental trap spectroscopy measurements, whereby negatively charge defects are compensated by positively charged defects that have unoccupied states in the band gap. These predictions will facilitate experimental identification of defect states in LaAlO3 and Al2O3 and their effect on nanodevices.
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Park, Seung Chul. "Study of optical properties of multi-crystalline Si and of heavily dislocated single-crystalline Si". Thesis, King's College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314286.
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Kokkaliaris, Stylianos. "Investigation of the vortex phase diagram and dynamics in single crystalline samples of the high temperature superconductor YBaâ†2Cuâ†3Oâ†7â†-â†#delta#". Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310294.
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Botura, Valdenir Aparecido. "Estudo de defeitos estruturais e dos fenômenos plásticos/frágeis em monocristais óxidos". Universidade de São Paulo, 1990. http://www.teses.usp.br/teses/disponiveis/54/54132/tde-13122013-150508/.
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Utilizando a técnica de ataque químico e microdureza realizamos um estudo sistemático dos defeitos estruturais e da microplasticidade em monocristais pertencentes ao sistema (BSCC) e em monocristais de LiNbO3. Desenvolvemos uma solução apropriada com HNO3 e H2O nas proporções de 1ml:30ml durante 20 segundos para o ataque químico dos compostos do sistema BSCC e revelamos padrões de defeitos estruturais como deslocações, terráceos (terraceds) e agrupamentos (bunchs). Além disso, fizemos uma tentativa de identificar a composição real destes compostos usando as técnicas de microscopia ótica, difração de raio-x, Laue, fluorescência de raio-x, medidas de resistividade, microdureza e ataque químico. O comportamento plástico/frágil dos cristais de Niobato de Lítio foi estudado nos planos (00.1), (01.4) e (01.0). Analisamos também a distribuição das deslocações em torno das deformações plásticas produzidas por indentações de uma ponta Vickers nas superfícies de pólos de domínios positivo e negativo sobre plano (00.1). Alguns desses resultados, como no caso da revelação de defeitos estruturais e microdureza dos compostos do sistema BSCC, podem ser considerados inéditos. Os cristais de niobato de lítio crescidos em nossos laboratórios mostraram um comportamento frágil isotrópico não convencional para esse composto, quando submetidos a tratamentos térmicosWe used etching and microindentation techniques to study the structural defects, microplasticity and microhardness in Bi-Sr-Ca-Cu-O and LiNbO3 single crystals. To revel structural defects in Bi-Sr-Ca-Cu-O crystals was developed a suitable solution of HNO3 in the ratio 1:30. The results obtained showed that there are patterns of structural defects as dislocations, terraceds and bunches in these compounds. We also did an attempt to identify the actual compositions of these compounds using optical microscopy, x-ray diffraction, Laue pattern, X-ray fluorescence, resistivity, microhardness and etching techniques. In LiNbO3 single crystals we analyzed the dislocations distributions around the plastic deformations produced by indentation experiments. The behavior plastic/fragile in LiNbO3 crystals were studied on three different perpendicular directions: to the Z-axis, to the 128 and to the (01.0). Some of these results, as the structural defects revelation and the microhardness in Bi-Sr-Ca-Cu-O compounds as well, were obtained at the first time. Also, unusual fragile behavior isotropic of LiNbO3 grown in our laboratory was found
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Hachet, Guillaume. "Multi-scale investigation of the consequences of hydrogen on the mechanical response of cyclically strained nickel single crystal". Thesis, La Rochelle, 2018. http://www.theses.fr/2018LAROS022/document.
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La fragilisation par l’hydrogène est une des causes les plus évoquées lors de la rupture prématurée des pièces métalliques. Il est donc nécessaire de clarifier l’effet de ce soluté sur les propriétés mécaniques et les mécanismes de plasticité dans ces matériaux. L’étude proposée de cette thèse consiste à étudier l’effet de l’hydrogène sur la réponse mécanique du nickel monocristallin déformé par la fatigue de l’échelle macroscopique jusqu’à l’échelle atomique. A l’échelle macroscopique, des essais de fatigue ont été réalisés sur du nickel orienté en glissement multiple avec plusieurs teneurs en hydrogène pour évaluer ses conséquences sur l’écrouissage cyclique du métal. Ensuite, une caractérisation microstructurale des hétérogénéités développées par la fatigue a été conduite pour plusieurs amplitudes de déformation plastique sur le nickel avec et sans hydrogène. La déformation du métal induit une organisation de la microstructure sous forme de chenaux et de murs qui dépend en partie des interactions élastiques entre l’état de contrainte, l’hydrogène et les défauts cristallins. Par conséquent, l’impact de l’hydrogène sur les propriétés élastiques du métal a été étudié à l’aide de calculs à l’échelle atomique et complété par des expériences. D’autres calculs à cette échelle, associés à des modèles analytiques basés sur la théorie élastique des dislocations, ont été réalisés pour évaluer la stabilité des structures de dislocations induites par la fatigue en présence d’hydrogène, de lacunes et d’amas de lacunes. Les principales conclusions de cette étude proviennent d’une analyse multi-échelle des résultats obtenus par la combinaison d’approches numériques et expérimentales. Nous suggérons que l’incorporation de l’hydrogène induit un durcissement intrinsèque du nickel. Cependant, la formation de lacunes et d’amas de lacunes atténue l’effet du soluté et participe à la compétition entre adoucissement et durcissement du nickel à l’échelle macroscopiqueHydrogen in metals can lead to irreversible damages on engineering structures. Consequently, the effects of the solute on the mechanical properties and the plasticity mechanisms of these materials have to be clarified. The proposed study consists to investigate the effects of hydrogen on the mechanical response of nickel single crystal strained by fatigue from macroscopic scale down to the atomic scale. At macroscopic scale, cyclic tests are conducted on multi-slip oriented nickel with several hydrogen concentrations to evaluate its consequences on the cyclic hardening of the metal. Then, a microstructural characterisation of the heterogeneities developed by fatigue is conducted for several plastic deformation amplitudes on nickel with and without hydrogen. The deformation of the metal induces a microstructure in form of wall and channel phases, which partially depend on the elastic interactions between the stress state, hydrogen and the induced crystalline defects. Therefore, the impact of hydrogen of the elastic properties of nickel single crystal is investigated using atomic scale calculations and experiments. Further calculations at this length scale associated with analytical elastic models are conducted to evaluate the stability of fatigue induced dislocation structures in presence of the solute, vacancies and vacancy clusters. The main conclusions of this study arise from the analysis of the results obtained from macroscopic scale down to the atomic scale and from the combination of both numerical and experimental techniques. In particular, the incorporation of hydrogen leads to a hardening of the nickel intrinsically. However, the formation of vacancies and vacancy clusters by the incorporation of hydrogen counteracts the effects of the solute and participates in the competition between the softening and the hardening of cyclically strained nickel single crystal observed at macroscopic scale
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Fanchon, Eric. "Etude structurale de conducteurs ioniques unidimensionnels de type hollandite". Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37604938h.
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Hung, Wei-Jie, i 洪偉傑. "Fabrication of Transparent Conductive Oxides for Single-Crystalline n-type Silicon Hetero-Junction Solar Cells". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/50732695248536570600.
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碩士華梵大學
機電工程學系博碩專班
98
This paper is aimed to improve the efficiencies of silicon solar cell using semiconductor fabrication technologies. The research first adopts n-type (100) silicon wafers as substrates, and applies KOH etching in the photolithography process to form inverted pyramid structures. The density of the inverse pyramid structures is varied to investigate its impact factor on the reflectivity for the solar cells. In addition, the paper performs high-density plasma chemical vapor deposition to fabricate amorphous silicon thin films. Then, the author can study solar cells performances with single crystal / hydrogenised amorphous silicon heterojunctions, the effects of p-type amorphous silicon films deposited over p-type single crystal films, as well as the influences from p-type amorphous silicon layers and intrinsic layers. Also, the research executes ion implantation to fabricate BSF layers, which are intended to decrease the carrier recombination rate within the interfacing regions, and to improve the minority carrier collection rates. Furthermore, this research employes RF sputtering system to fabricate AZO transparent conductive thin films, and then learns the effects of adjusted processing parameters to the electrical and optical film properties. In the end, hydrogen plasma is used to perform the film post-processing, and the conductive films are then utilized as solar cell electrodes. After using a semiconductor parameter analyzer to perform a series of experimental measurements, the obtained IV curves suggest that the prototyped solar cells can obtain an open circuit voltage Voc = 0.60V, a short circuit current Jsc = 30mA/cm2, a fill factor FF of 62.08%, and an actual efficiency is about 11.13%.
Części książek na temat "Defects - Single Crystalline Oxides"
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GUSTAFSSON, TORGNY, ERIC GARFUNKEL, LYUDMILA GONCHAROVA, DMITRI STARODUB, ROBIN BARNES, MATEUS DALPONTE, GENNADI BERSUKER i in. "STRUCTURE, COMPOSITION AND ORDER AT INTERFACES OF CRYSTALLINE OXIDES AND OTHER HIGH-K MATERIALS ON SILICON". W Defects in High-k Gate Dielectric Stacks, 349–60. Dordrecht: Springer Netherlands, 2006. http://dx.doi.org/10.1007/1-4020-4367-8_28.
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Dispinar, Derya. "Melt Quality Assessment". W Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-120052503.
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It is well known that the reaction of liquid aluminum with the moisture in the environment results in two products: aluminum oxide and hydrogen gas that dissolves in aluminum. Both of these products are considered to be detrimental to the properties of aluminum alloys. Therefore, test equipment has been developed to check the levels of these defects in the melt. Many of these involve expensive and consumable tools. In addition, an experienced personnel may be required to interpret the results. Nonetheless, aluminum oxide is harmless as long as it remains on the surface. The problem begins when this oxide is entrained into the liquid aluminum such as turbulence during transfer or mold filling in a non-optimized design. This can only happen by folding of the oxide. During this action, rough surface of the oxides comes in contact to form no bonds. These defects are known as bifilms that have certain characteristics. First, they act as cracks in the cast parts since they are oxides. It is important to note that aluminum oxide has thin amorphous oxide (known as young oxides) and thick crystalline oxide (γ-Al2O3) that may be formed in a casting operation. Second, almost zero force is required to open these bifilms due to the unbonded folded oxide skins. Thus, these defects can easily form porosity by unravelling during solidification shrinkage. On the other hand, the formation of porosity by hydrogen is practically impossible. Theoretically, hydrogen has high solubility in the liquid but it has significantly low solubility in solid aluminum. Thus, it is suspected that hydrogen is rejected from the solidification front to form hydrogen gas and porosity. However, the hydrogen atom has the smallest atomic radii and high diffusibility. Therefore, segregation of hydrogen in front of the growing solid is difficult. In addition, the energy required for hydrogen atoms to segregate and form hydrogen gas molecule is around 30,000 atm. Under these conditions, porosity formation by hydrogen is not likely to be achieved. Hydrogen probably stays in a supersaturated state or diffuses homogeneously through the cast part. The effect of hydrogen can only be seen when it can diffuse into the unbonded gap between the bifilms to open them up to aid the unravelling of bifilms to form porosity. This phenomenon can be easily detected by a very simple test called reduced pressure test. When a sample is solidified under vacuum, the bifilms start to open up. Since all porosity is formed by bifilms, the cross section of the sample solidified under vacuum can be analyzed by means of image analysis software. The sum of maximum length of pores can be measured as an indication of melt quality. Since bifilms are the most detrimental defects, this value is called “bifilm index” given in millimetres, which makes this test the only test that can quantify aluminum melt quality in such detail including both the effects of bifilms and hydrogen together. Several Al-Si alloys were used at various conditions: degassing with lance, ceramic diffusers, and graphite rotary has been compared. Gravity sand casting, die casting, and low-pressure die casting methods were evaluated. The effect of grain refiners and modifiers was studied. And the evolution of the bifilm index has been presented.
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"Single crystalline PZT films and the impact of extended structural defects on the ferroelectric properties". W Handbook of Advanced Dielectric, Piezoelectric and Ferroelectric Materials. CRC Press, 2008. http://dx.doi.org/10.1201/9781439832882.ch23.
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Vrejoiu, I., D. Hesse i M. Alexe. "Single crystalline PZT films and the impact of extended structural defects on the ferroelectric properties". W Handbook of Advanced Dielectric, Piezoelectric and Ferroelectric Materials, 695–723. Elsevier, 2008. http://dx.doi.org/10.1533/9781845694005.6.695.
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Wang, Jingyi, Hui Xiao i Huaxin Wang. "Modification Strategies of Titanium Dioxide". W Updates on Titanium Dioxide [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.111636.
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Titanium dioxide (TiO2) is a standard white pigment. However, when TiO2 is exposed to ultraviolet light, it will catalyze the degradation of the surrounding organic matrix. Surface coating of TiO2 is an effective method for reducing the catalytic effect of TiO2. It can also improve the dispersion of TiO2 in an organic matrix. This review critically introduces recent results on the surface coating of TiO2. First, the main features of TiO2, including processes, structure, and final properties, are described briefly. Second, this chapter reports and discusses different surface coating methods for TiO2 with inorganic oxides and organic matter. Inorganic oxides, such as Al2O3, SiO2, and ZrO2, would form a continuous dense film and block the defects of the TiO2 lattice. They can give TiO2 excellent weather resistance. The organic matter available for surface treatment includes the surfactant, the coupling agent, and the macromolecule. They can improve the affinity of TiO2 with various organic matrices. Surfactant treatment is relatively simple. Coupling agents can give TiO2 more novel properties, such as thermal stability. Macromolecules can increase the volume of TiO2 particles through steric hindrance and improve the dispersion of TiO2 in an organic matrix. However, coating TiO2 in a single matter is challenging to meet the increasing performance requirements. Therefore, it is necessary to study further the effect of co-coating with different inorganic oxides and organic matter on the structure and properties of TiO2.
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Bogomol, Iurii, i Petro Loboda. "Directionally Solidified Ceramic Eutectics for High-Temperature Applications". W MAX Phases and Ultra-High Temperature Ceramics for Extreme Environments, 303–22. IGI Global, 2013. http://dx.doi.org/10.4018/978-1-4666-4066-5.ch010.
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The processing techniques, microstructures, and mechanical properties of directionally solidified eutectic ceramics are reviewed. It is considered the main methods for preparing of eutectic ceramics and the relationships between thermal gradient, growth rate, and microstructure parameters. Some principles of coupled eutectic growth, main types of eutectic microstructure and the relationship between the eutectic microstructure and the mechanical properties of directionally solidified eutectics at ambient and high temperatures are briefly described. The mechanical behavior and main toughening mechanisms of these materials in a wide temperature range are discussed. It is shown that the strength at high temperatures mainly depends on the plasticity of the phase components. By analyzing the dislocation structure, the occurrence of strain hardening in single crystalline phases during high-temperature deformation is revealed. The creep resistance of eutectic composites is superior to that of the sintered samples due to the absence of glassy phases at the interfaces, and the strain has to be accommodated by plastic deformation within the domains rather than by interfacial sliding. The microstructural and chemical stability of the directionally solidified eutectic ceramics at high temperatures are discussed. The aligned eutectic microstructures show limited phase coarsening up to the eutectic point and excellent chemical resistance. Directionally solidified eutectics, especially oxides, revealed an excellent oxidation resistance at elevated temperatures. It is shown sufficient potential of these materials for high-temperature applications.
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Bokstein, Boris S., Mikhail I. Mendelev i David J. Srolovitz. "Diffusion". W Thermodynamics and Kinetics in Materials Science. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780198528036.003.0012.
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Diffusion is associated with the random, thermal motion of atoms that produces a change in the macroscopic concentration profile. This process occurs in gases, liquids, amorphous and crystalline solids of metals, ceramics, polymers, semiconductors, etc. The investigation of diffusion provides valuable information about the atomic structure of materials and the defects within them. Perhaps, most importantly, diffusion controls the rates of a wide range of kinetic processes associated with the synthesis of materials, processes by which we modify materials, and processes by which materials fail. The most common driving force for diffusion in a single-phase systems is associated with the entropy of mixing of its constituents (recall that we showed that the entropy of mixing of gases and the components of an ideal solution are always positive—see Sections 1.2.6 and 3.3). Since diffusional processes occur through the thermal motion of atoms (see below), it will not be surprising to learn that the rate of diffusion increases with increasing temperature. However, note that while the mechanisms of thermal motion in gases (random collision of atoms with each other) and liquids (e.g. Brownian motion) necessarily lead to mixing, the mechanisms of mixing within a solid are not as obvious. In solids, thermal motion corresponds to the vibrations of atoms near their equilibrium positions. Since the amplitude of such vibrations is much smaller than the nearest-neighbor separation, it would seem that such thermal motions cannot lead to mixing. Thus, the question ‘‘how do atoms migrate in solids’’ is not so simple. The equations describing diffusion were suggested by the physiologist Fick in 1855 as a generalization of the equations for heat transfer suggested by Fourier in 1824. Fick’s equations for diffusion can be obtained by analogy with Fourier’s equations for heat transfer by replacing heat with the number of atoms, temperature with concentration, and thermal conductivity with diffusivity. Fick’s first law provides a relationship between atomic currents and concentration gradients. As discussed above, this relationship can be understood by analogy with thermal conductivity or electrical conductivity.
Streszczenia konferencji na temat "Defects - Single Crystalline Oxides"
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Bundhoo, Fayik M., i Soundaranathan Kasivisvanatha. "A Novel Fault Isolation Technique for Identifying Deep Sub-Micron Defects". W ISTFA 2003. ASM International, 2003. http://dx.doi.org/10.31399/asm.cp.istfa2003p0465.
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Abstract A novel failure analysis approach has been developed to isolate and characterize deep sub micron defects in P<100>- silicon lattice. This technique utilizes unique wet chemical deprocessing and side wall cleaning in conjunction with focused ion beam milling to isolate a single vertical failing DMOS source contact from a parallel array of 462K contacts covered with oxide dielectric and top metal layers. The two methods of analysis and root cause of crystalline lattice dislocation in a vertical DMOS transistor are discussed. TEM examination of implanted dopant interface was carried out in order to determine the nature and origin of lattice dislocations. A study1 indicates that lattice dislocations are generated by deep boron and arsenic implants that are not adequately annealed. In our analysis, these dislocations were observed as loop pairs causing low-level leakage that did not initially allow the part to fail. However, these silicon lattice dislocations do pose reliability issues.
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Galindo, Felippe de Oliveira, Lucas Pires Gomes Oliveira, José Roberto Ribeiro Bortoleto, Nilson C. da Cruz, Elidiane C. Rangel i Steven F. Durrant. "Hole transport layers deposited by magnetron sputtering". W III SEVEN INTERNATIONAL MULTIDISCIPLINARY CONGRESS. Seven Congress, 2023. http://dx.doi.org/10.56238/seveniiimulti2023-028.
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Nickel oxide films have been widely studied as hole transport layers in perovskite solar cells because they present good chemical stability and nickel is abundant in nature. In this study, films were deposited using Magnetron Sputtering with a pulsed source. The NiOx films were deposited over an aluminum zinc oxide (AZO) film, which is non-toxic and cheap. The effects of varying the pulse duration on the deposition rate, film chemical composition, structure, optical and electrical characteristics were investigated. Films were produced in a chamber with pressures ranging from 3.06 to 4.01 mTorr. To activate the plasma, a 1500 VA, 600 V transformer was used, along with a 1.5 kVA/220 V single-phase voltage. Energy dispersive X-ray spectroscopy (EDS) was used to determine the chemical composition of the NiOx films. Scanning electron microscopy (SEM) was employed to analyze surface defects of the films. X-ray diffraction showed peaks at 34.20° and 72.28°, indicating the crystalline structure of nickel oxide. Optical properties of the films were obtained from UV-Vis-NIR spectra in the 200 to 2500 nm range. Films deposited with low pulses with 50 and 60 µs had transmittances of between 89 and 91% in the near infrared region. From the transmittance and reflectance data, the optical gap energies were calculated, which varied from 3.38 to 3.70 eV. In addition, the Urbach energy varied from 0.348 to 0.625 eV.
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Sankur, H., W. Southwell, R. Hall i W. J. Gunning. "Rugate Filter Deposition by the OMVPE Technique". W Optical Interference Coatings. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oic.1992.otub5.
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Organometallic vapor phase epitaxy (OMVPE) is a deposition technique that is increasingly applied to large scale manufacturing of electronic devices. This technique can produce single crystalline, high purity epitaxial layers with good thickness and composition controllability and can achieve high deposition rates (>10 nm/sec). For optical coatings, the crystalline nature of the layers ensures the absence of defects and therefore enhanced reliability and environmental stability.
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Li, Li, Andrew Gouldstone i Sanjay Sampath. "Intrinsic Properties of Thermal Sprayed Single Splats on Substrates". W ITSC2004, redaktorzy Basil R. Marple i Christian Moreau. ASM International, 2004. http://dx.doi.org/10.31399/asm.cp.itsc2004p1098.
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Abstract Splats are the building blocks of thermal sprayed coatings, and thus the mechanical properties of such coatings are directly related to splat behavior. Elastic and elastoplastic properties of coatings have been measured on the macro-scale, but are not yet quantitatively predictable using process parameters as inputs. Coating mechanical properties represent contributions from intrinsic splat properties, splat-splat interfaces, and other microscopic defects. In this study, we investigated the intrinsic properties of Ni and Ni based alloy splats on substrates, for a variety of process methods and input parameters. Residual stresses were measured via X-ray microdiffraction and elastic and elastoplastic properties were studied via nano-indentation. From a purely scientific standpoint, splat studies provide insight into rapidly cooled small-volume structures that often exhibit extra ultrafine- or nano-crystalline structure. Thus, accordingly, nano-indentation response was also compared to the prediction for bulk counterparts of the splat materials.
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Lin, Hung-Sung, Tung-Hung Chen i Wen-Cheng Shu. "Applications of C-AFM and CBED Techniques to the Characterization of Substrate Dislocations Causing SRAM Soft Single-Column Failure Contained in a Wafer with (001) Plane/[100] Notch". W ISTFA 2008. ASM International, 2008. http://dx.doi.org/10.31399/asm.cp.istfa2008p0260.
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Abstract SRAM memory is an ideal vehicle for defect monitoring and yield improvement during process development because of its highly structured architecture. However, the success rate of defect detection, especially for soft single-column failures, is decreasing when traditional physical failure analysis (PFA) with only the bitmap is available for guidance. This is due to a variety of invisible or undetectable defects that cause leakage in the device. In order to understand the leakage behavior in advanced high voltage (HV) processes, a Conductive Atomic Force Microscope (C-AFM) [1-4] is introduced to perform junction-level fault isolation prior to attempting PFA. According to J. P. Morniroli [5], crystalline defects affect convergent-beam electron diffraction (CBED) and large angle convergent-beam electron diffraction (LACBED) patterns, so CBED and LACBED techniques were also applied to the specimens containing dislocations to allow further characterization of these defects. In this study quantified data extracted using the C-AFM is also used to establish a connection between the failure mechanism discovered and the soft single column failure mode.
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Chen, C. Q., P. T. Ng, S. P. Neo, P. K. Tan, A. C. T. Quah i J. Zhu. "Application of Nanoprobing on Subtle Defects in the Embedded Non-Volatile Memory Device". W ISTFA 2019. ASM International, 2019. http://dx.doi.org/10.31399/asm.cp.istfa2019p0336.
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Abstract Non-volatile memory is the most important memory device in IC chips. As a memory, embedded non-volatile memory (NVM) is a fundamental structure in many kinds of semiconductor devices. It is commonly used in the modern electrical appliance as a code or data memory. For different applications, there are different memory designs or IP, like ROM, OTP, Flash, MRAM, PCRAM etc. The physical mechanism of these NVMs are different, some are electron based, some are resistance based and fuse or anti-fused based. The experiment described in this paper is performed on an electron charge storage based NVM. That means a medium is employed to store electron charge to differentiate two statuses “0” and “1”. Floating Poly gate is this medium used as electron charge storage in this NVM. Since the storage medium is in floating condition, it cannot be accessed externally. The methods of performing direct analysis are limited for this kind of device, especially in the case of subtle defects or soft fail. As semiconductor devices scale, the defects become smaller and more subtle. Nanoprobing is usually the only way to find the defect location electrically before any further physical analysis. In this experiment, the single bit NVM fail was analyzed. Different PFA methods used during the analysis, failed to find the defect. Nanoprobing was employed to precisely isolate the defect. Key word: nanoprobing, NVM, subtle defect, Poly-crystalline, floating gate
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Bunin, I., i N. Anashkina. "High-power nanosecond electromagnetic pulses and dielectric barrier discharge in air consequences on structural and structure sensitive properties of ilmenite surface". W 8th International Congress on Energy Fluxes and Radiation Effects. Crossref, 2022. http://dx.doi.org/10.56761/efre2022.c3-p-004001.
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The paper presents the results of experimental studies on the influence of two types of nonequilibrium electrical discharges (high-power nanosecond electromagnetic pulse (HPEMP) and dielectric barrier discharges (DBD) in air at atmospheric pressure) have on the surface morphology, microhardness, and physicochemical properties of natural ilmenite (Juina deposit of Brazil). Scanning electron microscopy (SEM-EDX), Fourier-transform infrared spectroscopy (FTIR), microhardness testing, contact angles of surface wetting, and streaming potentials are used to examine the morphology, defects, chemical composition of ilmenite surfaces, and its structure sensitive properties. Using FTIR, we established, the following possible mechanisms of the nonthermal effect of HPEMP and DBD low temperature plasma irradiation, which modify the structural state of ilmenite surfaces: (i) the transformation (destruction) of the mineral’s crystalline structure; (ii) the electrical disintegration and removal of fine films of iron oxides (hydroxides) from the ilmenite surfaces, and (iii) the subsequent hydroxylation and/or oxidation of Fe2+ to Fe3+ iron ions on the surfaces, due to the effect of the products of microdischarge plasmas. Advantages of using brief energy treatments (ttreat = 10–30 s) to modify the structural-chemical state of ilmenite surfaces and the physicochemical properties of mineral in order to improve the efficiency of processing complex titanium ores are shown. Keywords: ilmenite, high-power nanosecond electromagnetic pulses, dielectric barrier discharge, surface, microscopy, spectroscopy, microhardness, electrokinetic potential, contact angle.
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Moldovan, Grigore, Shark Lotharukpong i Peter Wilshaw. "Automated Defect Analysis in Solar Cells Using EBIC". W ISTFA 2014. ASM International, 2014. http://dx.doi.org/10.31399/asm.cp.istfa2014p0156.
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Abstract Electron Beam Induced Current (EBIC) characterization is unique in its ability to provide quantitative high-resolution imaging of electrical defects in solar cells. In particular, EBIC makes it possible to image electrical activity of single dislocations in a Dual-Beam Focused Ion Beam (FIB) Scanning Electron Microscope (SEM), to cut and lift out a micro-specimen containing a particular dislocation, and then transfer it for further structural or chemical analysis. As typical solar cell material presents a complex array of defects, it is important to observe statistical variations within a sample and select key sites for analysis. This paper describes a method for automated defect identification and characterization, and shows an application to multi-crystalline silicon (mc-Si) solar cell wafers selected from different heights along the manufactured ingot. Information presented here includes the experimental setup for data acquisition, as well as the basic algorithms used for identification and extraction of dislocation contrast.
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Aloy, A. S., R. A. Soshnikov, D. B. Lopukh, D. F. Bickford, C. C. Herman, E. W. Holtzsheiter i R. W. Goles. "Vitrification of DOE Simulated Radioactive Waste by Induction-Heated Cold-Crucible Melter Technology". W ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4907.
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Certain waste streams of the US DOE contain radioactive refractory oxides and other components like aluminum zirconium and chromium, which present difficulties during their processing and immobilization. The vitrification of such waste in joule-heated melters at high waste loading is possible only at a temperature exceeding 1150°C. The Khlopin Radium Institute (St.-Petersburg, Russia) jointly with the US Department of Energy has performed a feasibility study on the suitability of the Cold-Crucible Induction Heated Melter (CCIM) technology for the single-stage solidification of a surrogate sludge (C-106/AY-102 HLW Simulant), similar in composition to the High Level Waste (HLW) found at DOE’s Hanford Site (Richland, USA). During the experiments, slurry of simulated sludge and glass formers was metered directly to the CCIM, melted, and the glass product was poured from the melter. The melts were conducted at a mean melt temperature of 1350°C. The experiments produced borosilicate glass wasteforms with a waste oxide loading of 70 weight percent. According to the X-Ray diffraction analysis, the final product had a glass-crystalline structure. The crystalline phase was represented by spinel, (Fe,Mn)Fe2O4, uniformly distributed over the wasteform. The chemical durability of the samples was tested by the Product Consistency Test (PCT), and was considered durable according to the DOE specifications for HLW. In the course of the experiments, data were accumulated on the specific electric power consumption and the throughput of the facility.
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Soref, Richard A., i J. P. Lorenzo. "Epitaxial silicon guided-wave optical components for ̩λ = 1.3 µm". W Integrated and Guided Wave Optics. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/igwo.1986.wdd5.
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Single-crystal silicon is a promising new material for integrated-optical components, both active and passive, that operate at λ = 1.3 and 1.6 µm. According to the data of Fan et al.1 and Swimm,2 high-purity monocrystal silicon is highly transparent at the 1.3- and 1.55- µm fiber-optical communications wavelengths. (The absorption spectrum is shown in Fig. 1.) The absorption coefficient can be as low as 10−3 cm−1 when ρ = 104 Ω cm. Thus, in theory, silicon is suitable for low-loss waveguiding at these wavelengths. Experimentally, we have examined the conditions of epitaxy, ion implantation, diffusion, annealing, and doping that are appropriate for making guiding layers. It is important to control the morphology and crystallinity of the guiding layer because optical scattering and absorption will increase if grain boundaries and lattice defects are present. Thus polycrystalline-Si and amorphous-Si are less desirable for guiding than crystalline-Si. In recent years, epitaxial growth techniques for single-crystal Si have been perfected for VLSI and discrete electronic device applications.