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Grundy, Michael J. "Neutron scattering from interfaces." Thesis, University of Bristol, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357011.
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Sorrell, Courtney Davis. "Fundamental studies of responsive microgel thin films at interfaces." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24679.
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Thesis (Ph.D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009.Committee Chair: Lyon, L. Andrew; Committee Member: Beckham, Haskell; Committee Member: Janata, Jiri; Committee Member: Pielak, Gary; Committee Member: Ragauskas, Arthur
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Clarke, John. "X-ray scattering from thin films and interfaces." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4499/.
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The non-destructive study and characterisation of thin films and their interfaces, on an atomic scale, is a crucially important area of study in many areas of science and technology. In this thesis both high angle and grazing incidence x-ray scattering techniques have been used to study the effect of depositing thin films on surfaces with a periodic roughness, as well as studying the structure of laterally modulated surfaces themselves. High angle diffraction measurements of the out-of-plane size of Co crystallites and the crystalline texture of the Ag lattice, in a series of CoAg granular fihns, has allowed a consistent growth mechanism for the Co grains to be deduced. In grazing incidence scattering studies of this series of thin, granular films it was observed that the diffuse scatter was offset from the specular condition and the position of this offset was seen to vary, sinusoidally, upon rotation of the sample. This led to the conclusion that the growth techniques employed had caused a regular step-bunching of the Si (111) substrate. As step-bunching of surfaces can affect greatly the properties of thin films deposited on them, the ability to characterise the substrate after growth is extremely important. In spin-valves deposited on rough, tiled, silicon oxide substrates, the presence of strong interference fringes in the off-specular scatter demonstrated that vertically conformal roughness dominated the system and this was seen to result in the degradation of the magnetic sensitivity of the samples. Conversely, an enhancement in the photoluminescence from thin polymer films deposited on laterally modulated substrates led to a series of studies being made on such structures. In order to obtain information on the lateral period of such structures, as well as their roughness and thickness, existing scattering theories have been modified and a semi-kinematical code of the coherent scatter has been developed.
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Erdy, Christine. "Self-Assembled Host-Guest Thin Films for Functional Interfaces." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/36049.
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The functionalization of surfaces has received attention because the process allows the design and tailoring of substrate surfaces with a new or improved function.
â Host-guestâ thin film complexes are composed of â hostâ molecules attached the substrate surface, either through physisorption or covalent bonds, with cavities for the inclusion of desired â guestâ molecules for the functionalization of the surface. Two methods for fabricating functional â host-guestâ thin films were investigated: Langmuir-Blodgett (LB) deposition and self-assembly monolayer (SAM). Langmuir films were created at the air-water interface using octadecanesulfonic acid (C18S) as the amphiphilic â hostâ molecules separated by hydrophilic guanidinium (G) spacer molecules, which created a cavity allowing the inclusion of desired â guestâ molecules. Surface pressure-area isotherms of the (G)C18S, with and without guests, are characterized by the lift-off molecular areas and are use to determine the proper deposition surface pressure. â Host-guestâ Langmuir films are deposited onto silicon substrates using the LB deposition technique. The LB films were then subjected to stability testing using different solvents over increasing periods of time. Grazing-angle incidence X-ray diffraction (GIXD), specular X-ray reflectivity (XRR) and transfer ratio measurements were used to characterize the crystallinity, film thickness, overall film stability and film coverage. The GIXD data revealed that the crystallinity of the deposited film varies with the â guestâ molecules and can be disrupted by the functional group on the â guestâ molecule through hydrogen bonding. After modeling the XRR data using StochFit, it was discovered that the more polar solvent, tetrahydrofuran (THF), removed the film completely while the nonpolar solvent, hexane, compacted the thin film and increased the electron density. With transfer ratios around 0.95 to 1.05, the deposited films were homogenous.
The second method used was self-assembly monolayers, which differs from Langmuir films in that they are created by a spontaneous chemical synthesis from immersing a substrate into a solution containing an active surfactant. Octadecyltrichlorosilane (OTS) was used initially as a molecule to study the self-assembled monolayer procedure. To study a â host-guestâ self-assembled monolayer system, a compound is being synthesized from 9-bromoanthracene. This compound would already contain the cavity necessary for the inclusion of â guestâ molecules. The solution that contained OTS was composed of a 4:1 mixture of anhydrous octadecane: chloroform. Silicon substrates with a deposited oxide layer were hydroxylated for the surfactant binding chemical reaction to occur. The OTS SAMs were exposed to the same stability tests as the LB films. Surface contact angle measurements were taken of the OTS SAMs before and after the stability tests. The contact angle prior to the stability tests was 110° (±2°). The contact angle after immersion in THF was 101° (±2°) while the contact angle resulting from immersion in hexane was 105° (±2°). From the contact angle measurements, the degradation of the OTS SAMs was less extensive than that of the (G)C18S LB films.Master of Science
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Sainju, Deepak. "Spectroscopic Ellipsometry Studies of Ag and ZnO Thin Films and Their Interfaces for Thin Film Photovoltaics." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1430326934.
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Burrows, Christopher W. "Growth and characterisation of MnSb thin films and interfaces." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/55927/.
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The deposition of Mn on to reconstructed InSb and GaAs surfaces has been studied by re ection high-energy electron diffraction (RHEED), atomic force microscopy and scanning tunnelling microscopy. On both Ga- and As-terminated GaAs(001), a Mn-induced (2x2) reconstruction is observed. In contrast, there are no well defined Mn-induced surface reconstructions on InSb. Islands are observed to form on all of the surfaces studied, with islands on the Group III-rich surfaces composed of elemental Mn and of an alloy on the Group V-rich surfaces. The conversion from Group III(V)-rich to Group V(III)-rich surfaces are discussed in terms of basic thermodynamic quantities and a number of models for surface atom substitution are proposed as pathways for MnAs and MnSb island formation. A high resolution X-ray diffraction study (HRXRD) has been performed on niccolite, cubic and wurtzite crystallites present within MnSb thin films grown on GaAs(111) substrates. It is observed that the lattice parameters of the polymorphs do not depend on the film thickness or the time-corrected beam ux ratio, J. The niccolite phase is found to relax rapidly (within 3 nm) and the average c lattice parameter of these films is 5.791(1) A. Variations in the c lattice parameter indicate that the average stoichiometry of the films varies on a per sample basis and this may act to promote the formation of polymorphs. Cubic MnSb crystallites exhibit a large strain dispersion of approximately 1 % and a rhombohedral or trigonal distortion is believed to be the origin. Quantitative analysis of asymmetric reciprocal space maps reveals that films grown using the optimised conditions have the highest concentration of the cubic polymorph, with lower values of J in the optimised range promoting this polymorph. The growth of MnSb on Ge(001) and Ge(111) substrates has been investigated. On Ge(001) growth proceeds through the formation of three dimensional islands and no dependence on the growth conditions is observed. Evidence for (1102) and (1120) crystallites is seen in XRD and RHEED, respectively. The interface between the MnSb islands and the Ge(001) substrate is sharp with no evidence for interfacial reactivity. The epitaxial growth of MnSb on Ge(111) is reported for the first time. The growth orientation is confirmed to be (0001) by X-ray diffraction while the layers are found to be ferromagnetic with a Curie temperature in excess of 300 K.
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Zhao, Haibin. "Optical characterization of ferromagnetic heterostructure *interfaces and thin films." W&M ScholarWorks, 2006. https://scholarworks.wm.edu/etd/1539623494.
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This thesis presents optical characterizations of interfaces in ferromagnetic heterostructures and thin films used for spin polarized electronic devices. In these experiments, femtosecond laser spectroscopies are exploited to investigate the interface magnetization reversal, spin precession, and band offset, which are crucial in determining the performances of spintronic devices.;First, magnetization-induced second-harmonic-generation (MSHG) is applied to study interface magnetism in a hybrid structure containing a noncentrosymmetric semiconductor---Fe/AlGaAs. The reversal process of Fe interface layer magnetization is compared with the bulk magnetization reversal. In Fe/AlGaAs (001), the interface magnetization is found to be decoupled from the bulk magnetization based on the different switching characteristics---single step switching occurs at the interface layer, whereas two-jump switching occurs in the bulk. In contrast, the interface layer in Fe/AlGaAs (110) is rigidly coupled with the bulk Fe, indicating a strong impact of electronic structure on the magnetic interaction despite the same chemical composition. Furthermore, a time-resolved MSHG study demonstrates a coherent interface magnetization precession in Fe/AlGaAs (001), implying the feasibility of fast precessional control of interfacial spin. The interface magnetization precession exhibits a higher frequency and opposite phase for a given applied field compared to the bulk magnetization precession.;Second, uniform magnetization precession in the Lac0.67Ca 0.33MnO3 (LCMO) and La0.67Sr0.33MnO 3 (LSMO) films grown on different substrates are investigated by time-resolved magneto-optic Kerr effect. The parameters of magnetic anisotropy are determined from the field dependence of the precession frequency. The strain-free LCMO films grown on NdGaO3 exhibit a uniaxial in-plane anisotropy induced by the tilting of the oxygen octahedra in NdGaO3 An easy-plane magnetic anisotropy is found in the tensile-strained films grown on SrTiO 3, whereas the compressive-strained film grown on LaAlO3 exhibits an easy normal-to-plane axis.;Third, a table-top internal photoemission system is developed to measure the band offsets across semiconductor heterointerfaces by utilizing an optical parametric amplifier as the bright light source. The conduction band offsets DeltaE c = 660 meV and 530 meV at the CdCr2Se4-GaAs and CdCrZSe4-ZnSe interfaces are determined from the threshold energies of the photocurrent spectrum. The band offset is shown to be reduced by engineering the interface bonding and stoichiometry.
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Beerman, Michael. "Transverse freezing of thin liquid films /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/10573.
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Parks, Carl L. "An experimental approach for studying the creep behavior of thin film/ substrate interfaces." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sep%5FParks.pdf.
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Thornell, Mark E. "Sample fabrication and experimental design for studying interfacial creep at thin film/silicon interfaces." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Mar%5FThornell.pdf.
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Van, Wyck Neal Edward. "MULTIPHOTON SPECTROSCOPY OF THIN FILMS AND SURFACES (NONLINEAR, WAVEGUIDES, INTERFACES)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/291294.
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Shelford, Leigh. "Ultrafast nonlinear optical studies of multilayered thin films and interfaces." Thesis, University of Exeter, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506859.
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Yang, Fuzi. "Optically excited surface polaritons using strongly absorbing media." Thesis, University of Exeter, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279743.
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Zugic, Richard. "Modelling the tribology of thin film interfaces." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365788.
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Winnischofer, Herbert. "Interfaces e dispositivos baseados em porfirinas supramoleculares." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/46/46134/tde-28042009-214100/.
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Neste trabalho são descritas as propriedades morfológicas, condutoras, fotoeletroquímicas e eletrocatalíticas de filmes de porfirinas supramoleculares, contendo complexos de rutênio polipiridina e clusters trinucleares de rutênio. Foram empregadas técnicas de microscopia de varredura por sonda, voltametria cíclica, espectroscopia de impedância eletroquímica, espectroeletroquímica UV-vis, voltametria de disco rotatório e experimentos combinados de eletroquímica/fotoeletroquímica. Cálculos semi-empíricos foram utilizados em alguns casos para dar maior suporte às interpretações. O método de preparação dos filmes tem efeito drástico sobre o tipo de empacotamento do material. Conseqüentemente, as propriedades condutoras e fotoeletroquímicas também são afetadas. Por exemplo, o coeficiente de difusão eletrônica (DeCm2) pode variar até 104 vezes dependendo do tipo de empacotamento de uma mesma porfirina utilizada. Os processos de condução desses filmes são controlados por um mecanismo redox envolvendo os sítios de rutênio e são mediados por orbitais Ί* dos anéis porfirínicos e polipiridínicos. A intensidade de fotocorrente em função do λ incidente depende do mecanismo de transporte de elétrons e pode ser modulada pela natureza e grau de acoplamento eletrônico entre os anéis porfirínicos dentro do filme. Esses filmes exibem propriedades eletrocatalíticas na oxidação de substratos de interesse ambiental, da indústria alimentícia e do setor médico, tais como nitrito, sulfito e ácido ascórbico. As eficiências desses materiais são altas, com kf > 104 mol-1dm3s-1. Em catalisadores redox foi verificada uma tendência exponencial entre a constante cinética de transferência eletrônica heterogênea e potencial de E1/2 do centro redox no filme, como previsto pela equação de Marcus. A cobalto porfirina contendo quatro clusters trinucleares de rutênio se comporta como um eficiente catalisador molecular da redução do O2 por 4 elétrons, em pH < 5. O mecanismo de redução não envolve a bis-coordenação do O2 a dois sítios metálicos. Nesse caso, efeitos eletrônicos dos complexos periféricos devem ativar o centro da metaloporfirina, promovendo a transferência multieletrônica e prevenindo a formação de espécies reativas, como OH· e O2-. Uma célula de FIA foi construída visando a análise quantitativa de sulfito, exibindo alta eficiência em termos de limite de detecção, freqüência de análises e reprodutibilidade. O sistema FIA foi adaptado e empregado juntamente com o filme de uma porfirina supramolecular para reproduzir as funções básicas de um portal lógico, exibindo comportamento singular, podendo desempenhar as três funções (AND, OR e NOT) num único sistema químico integrado.A full characterization of the morphologic, conduction, photoelectrochemical and electrocatalytic properties of supramolecular porphyrin films containing ruthenium polypyridyl or ruthenium clusters, is described. Techniques, such as scanning probe microscopy, cyclic voltammetry, electrochemical impedance spectroscopy, UV-vis spectroelectrochemistry, rotating disk electrode voltammetry, and combined electrochemical/photoelectrochemical experiments were employed. Semi-empirical calculations were utilized in order to obtain more information on the interpretations. The preparation method of film deposition has a special effect on the material packing. Consequently, the conduction and photoelectrochemical properties are also affected. For example, the electronic diffusion coefficient (DeCm2) differs by up to 104 times depending on the packing characteristics of the same porphyrin material. The conduction process is limited by a redox mechanism involving the ruthenium centers and is mediated by π* orbitals of the porphyrin or polypyridine species. The photocurrent intensity as a function of the incident λ depends on the electron transport mechanism involved and this can be tuned by the nature and the degree of electronic coupling between the porphyrin rings, in the film. This kind of films also exhibits electrocatalytic activities for the oxidation of substrates with interests in the environmental, food and medical areas, such as nitrite, sulfite, and ascorbic acid. The efficiency of these materials are also high, with kf > 104 mol-1dm3s-1. An exponential relationship of the heterogeneous electron transfer kinetic constant with the E1/2 of the redox center was found, as predicted by the Marcus equation. The cobalt porphyrin containing four ruthenium clusters behaves as an efficient catalyst for the 4-electron reduction of O2, at pH <5. The mechanism does not involve the bis-coordination of O2 to two metallic centers, but electronic effects from the ruthenium clusters should be activating the metalloporphyrin center, promoting the multi-electronic transfer and preventing the formation of reactive species, such as OH· e O2-. A FIA cell was built in order to provide a quantitative analysis of sulfite, and it exhibited high sampling frequency, reproducibility, as confirmed by the low detection limit (0.1 µmol.dm-3). The FIA system was adapted and employed with a supramolecular porphyrin film as logic gates and they exhibited a unique behavior, operating the three basic functions (AND, OR and NOT) in a single integrated chemical system.
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Ścigaj, Mateusz. "Functional oxide films and interfaces: ferroelectric BaTiO3 films on Si(001) and conducting (110) and (111) LaAlO3/SrTiO3 interfaces." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/400603.
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La tesis aborda la integración monolítica de óxidos funcionales sobre silicio y la exploración de intercaras entre SrTiO3(110), SrTiO3(111) y otros óxidos
En primer lugar la tesis detalla la integración monolítica del BaTiO3 en silicio, la plataforma actual en microelectrónica. Para ello se ha usado la heteroestructura LaNiO3/CeO2/YSZ como capa de barrera química y acomodación estructural. Se han investigado las propiedades estructurales y funcionales. Las capas son epitaxiales y orientadas con el eje c perpendicular al substrato, y presentan rugosidad superficial muy baja y alta polarización ferroeléctrica en remanencia. El óxido ferrimagnético CoFe2O4 fue integrado seguidamente en la estructura. La estructura multifuncional obtenida presenta alta calidad estructural, con excelentes propiedades ferromagnéticas y ferroeléctricas a temperatura ambiente. Asimismo presentamos la integración de BaTiO3 epitaxial sobre Si usando SrTiO3 como capa de barrera. También en este caso los ciclos de polarización ferroeléctrica medidos señalan las buenas propiedades funcionales de la estructura. Se presenta una comparación de las propiedades estructurales y funcionales de BaTiO3 crecido sobre SrTiO3/Si(001) y sobre CeO2/YSZ/Si(001).
La segunda parte de la tesis se centra en las propiedades estructurales y de transporte de intercaras de LaAlO3/SrTiO3, con un especial énfasis en el estudio de la formación de un gas bidimensional de electrones en la intercara LaAlO3/SrTiO3(110). El análisis de la estructura y química de la intercara, de su jerarquía orbital electrónica, y de sus propiedades superconductoras amplían el conocimiento existente de los gases bidimensionales de electrones en intercaras de óxidos. Se han estudiado también las intercaras conductoras entre SrTiO3(110) y óxidos amorfos. El estudio ha permitido determinar la importancia relativa de la afinidad con el oxígeno de los metales depositados y la dependencia con la orientación de la energía de formación y difusión de vacantes de oxígeno. Además la tesis detalla el crecimiento monocapa a monocapa de Y:ZrO2 sobre SrTiO3(110), dando lugar a la relación epitaxial [110]YSZ(001) //[001]SrTiO3(110). Representa una nueva intercara presentando discontinuidad de simetría sin presentar variantes cristalinas gracias a usar la superficie de menor simetría como substrato, y abre paso al desarrollo de otras intercaras originales entre óxidos.In this thesis the focus was aimed to the monolithic integration of functional oxides on silicon and to the exploration of interfaces between different oxides and the SrTiO3(110) and SrTiO3 (111) surfaces. Herein we report the monolithic integration of ferroelectric BaTiO3 on silicon, the current platform for microelectronics. This was done using the LNO/CeO2/YSZ buffer layer. The structural and functional properties are investigated. The films are epitaxial an c-oriented. Very low surface roughness and high ferroelectric remanent polarization are reported. High crystal quality ferrimagnetic CoFe2O4 was subsequently integrated in the structure. Thus obtained multifunctional structure shows high structural quality, robust ferromagnetism and superior ferroelectric properties, all at room temperature. Moreover, we report the integration of epitaxial BaTiO3 on Si using SrTiO3 buffer layer. Also in this case the recorded ferroelectric loops point to the good functional properties of this structure. A structural and functional comparison is given between BTO grown on the thin SrTiO3 and CeO2/YSZ buffer layers on silicon. We also report on the structural and transport properties of LaAlO3/SrTiO3 interfaces, with special emphasis on the LaAlO3/SrTiO3(110) interface featuring two-dimensional electron gas (2DEG). Further analysis of the interface structure and chemistry, electronic orbital hierarchy and superconductivity enriched our knowledge of the 2DEG electronic properties. Special focus also was given to the conductive interfaces comprising SrTiO3(110) and amorphous oxides. This study enables us to disentangle the relative importance of the oxygen affinity of the deposited metals and the orientation-dependent energy of vacancy formation and diffusion on the creation of oxygen vacancies. In addition we report the layer by layer growth of Y:ZrO2 on SrTiO3(110), leading to the epitaxial relationship [110]YSZ(001) //[001]SrTiO3(110). This novel idea of an interface featuring a symmetry discontinuity with the substrate being the lower symmetry material paves the way towards development of other innovative oxide interfaces.
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Mathew, Anoop. "Study of interfacial phenomena in thin films using photoelectron spectroscopy." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 2.05 Mb., 74 p, 2006. http://wwwlib.umi.com/dissertations/fullcit/1435840.
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Zhang, Yi. "Three dimensional atom probe tomography of nanoscale thin films, interfaces and particles." [Ames, Iowa : Iowa State University], 2009.
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Benzaquen, Michael. "Dynamique des interfaces liquides, des films minces au sillage des bateaux." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066192.
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Nous présentons des résultats sur la dynamique des interfaces liquides à différentes échelles. Dans la première partie, nous étudions des systèmes liquides confinés dans le cadre de l'approximation de lubrification. Nous obtenons des résultats analytiques et numériques intéressants sur l'équation des films minces qui régit la dynamique de tels systèmes. Les résultats théoriques sont confrontés avec succès à des experiences de microscopie à force atomique sur des films minces de polymères dans différentes géométries. Nous explorons la physique qui résulte des effets inhérents à la nature des matériaux polymères tels que la viscoélasticité, le glissement aux parois ou encore la dynamique au voisinage de la température de transition vitreuse. Dans la deuxième partie, nous nous intéressons au sillage engendré par le mouvement d'une perturbation à l'interface liquide-air. Motivés par des résultats expérimentaux qui semblent remettre en question la théorie de Kelvin sur le sillage des bateaux, nous montrons que deux angles peuvent être distingués dans le sillage. L'angle que forment les bords du domaine est bien constant, conformément à la théorie de Kelvin, alors que l'angle que décrivent les vagues de plus forte amplitude décroit avec le nombre de Froude. Nous nous penchons également sur les ondes gravito-capillaires et portons un intérêt particulier aux effets de taille finie sur la résistance de vague. Les deux parties peuvent être abordées de manière indépendanteWe present results on the dynamics of liquid interfaces at different scales. In the first part, we study confined liquid systems within the lubrication approximation. We obtain interesting analytical and numerical results on the thin-film equation governing the dynamics of such systems. The theory is successfully confronted to atomic force microscopy experiments on thin polymer films in different geometries. We explore the physics resulting from the intrinsic properties of polymeric materials such as viscoelasticity, slip at the solid- liquid interface as well as the dynamics near the glass transition temperature. In the second part, we tackle the problem of the wake generated by a moving disturbance at the air-water interface. Motivated by experimental results that seem to challenge Kelvin’s century old theory of ship waves, we show that two angles can be distinguished in the wake. The angle delimiting the wake is constant, consistent with Lord Kelvin’s theory, while the angle corresponding to the highest waves decreases as the Froude number is increased. We examine as well the case of capillary-gravity waves and focus in particular on the finite size effects on the wave drag. Both parts can be addressed independently
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Blumenfeld, Michael Lewis. "LOCAL ELECTRONIC PROPERTIES OF ORGANIC SEMICONDUCTOR INTERFACES." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/194860.
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Understanding organic semiconductor interfaces is critical to developing organic photovoltaics (OPV). OPV interfaces are disordered due to weak intermolecular interactions, resulting in diverse charge transfer micro-environments. I present experimental data isolating high-order intermolecular interactions controlling interfacial energy level alignment and describe new instrumental capabilities providing access to the local electronic and kinetic landscape at organic semiconductor interfaces. Interface formation between vanadyl naphthalocyanine (VONc) and highly ordered pyrolytic graphite (HOPG) is investigated. Ultraviolet photoemission spectroscopy (UPS) shows that the VONc binding energy (BE) decouples from the work function, shifting in an opposite direction and contradicting the standard interface dipole model. This effect is quantitatively described using an electrostatic depolarization model and confirmed by simulations which show an inhomogeneous potential at the interface. New data and literature values suggest orthogonality between polarizability and molecular dipole in polar porphyrazines. Their potential for interface engineering is discussed. The electron-rich Au(111)/VONc interface is investigated. The organic layer induces a large interface dipole in Au(111) which can be fit to a depolarization model. Ionization potential and depolarization data suggest that the second VONc layer on Au(111) adopts a tilted geometry. Electrostatic differences between Au(111)/VONc and HOPG/VONc are discussed, demonstrating that interface dipole contributions are not interchangeable. The surface states of the Au(111)/VONc interface are characterized by angle resolved 2-photon photoemission to determine the magnitude of the perturbation. The measured free-electron-like effective mass and BE destabilization of the Shockley state is attributed to step edges caused by lifting the Au(111) (22 x √3) reconstruction. The Shockley state is accessible primarily through resonance with the n = 1 image state. Another resonance between the image state and a molecular state of VONc is tentatively identified. Design and construction of a confocal fluorescence microscope capable of single molecule detection in ultrahigh vacuum is described. Initial images and fluorescence trajectories demonstrate the ability to measure charge transfer kinetics between an individual organic semiconductor molecule and well-characterized insulating surfaces. Progress towards completion of a scanning photoionization microscope is presented. The microscope demonstrates diffraction-limited imaging capabilities using fs-laser-generated photoelectron current as contrast. Recommendations are given towards achieving spectral resolution and for future experimental systems.
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James, David William. "Characterisation of buried conjugated polymer interfaces by off specular neutron scattering." Thesis, Swansea University, 2011. https://cronfa.swan.ac.uk/Record/cronfa42678.
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Neutron reflectivity offers the opportunity for non-destructive characterisation of buried polymer interfaces. Specular neutron reflectivity is commonly used to characterise the structure of conjugated polymer interfaces found in organic electronic devices. However, detecting specularly reflected neutrons only allows the measurement of the root-mean-square (RMS) roughness of the interface averaged over a macroscopic lateral distance. There are two contributions to the RMS roughness of a polymer/polymer interface; i) the so-called 'intrinsic interfacial width' due to mixing of the polymers at a molecular level and ii) lateral roughness due to deviations of the interface position from the plane of the substrate. In this work a numerical model is developed to analyse experimental off specular reflectivity. The model is based on the distorted wave Born approximation (DWBA). Specular and off specular neutron reflectivity data is collected from a model conjugated polymer/amorphous polymer interface (poly(9,9-dioctylfluorene) (F8) on deuterated PMMA) and a conjugated poly- mer/fullerene interface (poly(3-hexylthiophene) (P3HT) polymer on [6,6]-phenyl C61-butyric acid methylester (PCBM)). This allows probing of the structure in the plane of the interfaces to distinguish the intrinsic interfacial width from the lateral roughness. The structure of the F8/dPMMA interface is studied by systematically varying the film thickness, which strongly impacts on the amplitude of the lateral interface roughness, and allows more complete analysis of the relative contributions of intrinsic mixing and lateral roughness. For comparison off specular measurements on amorphous/amorphous polymer (PMMA/polystyrene) interfaces are performed, which have been studied previously using specular neutron reflectivity and self consistent held theory. Fitting specular reflectivity using standard techniques and off specular reflectivity data using the model developed allow intrinsic and lateral roughness contributions for the F8/dPMMA system to be separated by direct measurement. The P3HT/PCBM interface exhibits no lateral roughness as the materials are found to be miscible.
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Corbett, Michael H. "Synthesis of thin film relaxor electroceramics and heterostructures." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343205.
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Liu, Ying. "Fabrication of Nanostructured Electrodes and Interfaces Using Combustion CVD." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7937.
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Reducing fabrication and operation costs while maintaining high performance is a major consideration for the design of a new generation of solid-state ionic devices such as fuel cells, batteries, and sensors. The objective of this research is to fabricate nanostructured materials for energy storage and conversion, particularly porous electrodes with nanostructured features for solid oxide fuel cells (SOFCs) and high surface area films for gas sensing using a combustion CVD process.
This research started with the evaluation of the most important deposition parameters: deposition temperature, deposition time, precursor concentration, and substrate. With the optimum deposition parameters, highly porous and nanostructured electrodes for low-temperature SOFCs have been then fabricated. Further, nanostructured and functionally graded La0.8Sr0.2MnO2-La0.8SrCoO3-Gd0.1Ce0.9O2 composite cathodes were fabricated on YSZ electrolyte supports. Extremely low interfacial polarization resistances (i.e. 0.43 Wcm2 at 700¡ãC) and high power densities (i.e. 481 mW/cm2 at 800¡ãC) were generated at operating temperature range of 600¡ãC-850¡ãC.
The original combustion CVD process is modified to directly employ solid ceramic powder instead of clear solution for fabrication of porous electrodes for solid oxide fuel cells. Solid particles of SOFC electrode materials suspended in an organic solvent were burned in a combustion flame, depositing a porous cathode on an anode supported electrolyte.
Combustion CVD was also employed to fabricate highly porous and nanostructured SnO2 thin film gas sensors with Pt interdigitated electrodes. The as-prepared SnO2 gas sensors were tested for ethanol vapor sensing behavior in the temperature range of 200-500¡ãC and showed excellent sensitivity, selectivity, and speed of response.
Moreover, several novel nanostructures were synthesized using a combustion CVD process, including SnO2 nanotubes with square-shaped or rectangular cross sections, well-aligned ZnO nanorods, and two-dimensional ZnO flakes. Solid-state gas sensors based on single piece of these nanostructures demonstrated superior gas sensing performances. These size-tunable nanostructures could be the building blocks of or a template for fabrication of functional devices.
In summary, this research has developed new ways for fabrication of high-performance solid-state ionic devices and has helped generating fundamental understanding of the correlation between processing conditions, microstructure, and properties of the synthesized structures.
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Tan, Xiaojing. "Study of magnetic thin films and magnetic interfaces by linear MOKE and second harmonic generation." Diss., UC access only, 2009. http://proquest.umi.com/pqdweb?index=146&did=1907174011&SrchMode=1&sid=1&Fmt=7&retrieveGroup=0&VType=PQD&VInst=PROD&RQT=309&VName=PQD&TS=1270495163&clientId=48051.
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Thesis (Ph. D.)--University of California, Riverside, 2009.Includes abstract. Includes bibliographical references (leaves 145-148). Issued in print and online. Available via ProQuest Digital Dissertations.
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Ercole, Ari. "Thin film magnetism at surfaces and interfaces." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624863.
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Wang, Dong. "Fatigue behavior of thin Cu films film thickness and interface effects /." Karlsruhe : Forschungszentrum Karlsruhe, 2007. http://d-nb.info/98578797X/34.
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Peri, Someswara Rao. "Interface Structure of Photonic Films Created by Plasma Enhanced Chemical Vapor Deposition." University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1271687789.
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Kast, Matthew. "Towards Tunable and Multifunctional Interfaces: Multicomponent Amorphous Alloys and Bilayer Stacks." Thesis, University of Oregon, 2017. http://hdl.handle.net/1794/22288.
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Controlling the electronic structure and requisite charge transfer at and across interfaces is a grand challenge of materials science. Despite decades of research and numerous successes in the fields microelectronics and photovoltaics much work remains to be done. In many applications, whether they be in microelectronics, photovoltaics or display technology there is a demand for multiple functions at a single interface. Historically, existent materials were either discarded as an option due to known properties or tested with some application based figure of merit in mind. Following this, the quality of the material and/or the preparation of the surface/interface to which the material would be deposited was optimized. As the microelectronics and photovoltaics industries have matured, continued progress (faster, lower power transistors and more efficient, cheaper, abundant solar cells) will require new materials (possibly not previously existent) that are fundamentally better for their application than their highly optimized existent counter parts. The manifestation of this has been seen in the microelectronics field with introduction of hafnium silicates to replace silica (which had previously been monumentally successful) as the gate dielectrics for the most advanced transistors. Continued progress in efficient, cheap, abundant photovoltaics will require similar advances. Advances will be needed in the area of new abundant absorbers that can be deposited cheaply which result in materials with high efficiencies. In addition, selective contacts capable of extracting charge from efficient absorbers with low ohmic losses and low recombination rates will be needed. Presented here are two approaches to the multifunctional interface problem, first the use of amorphous alloys that open up the accessible composition space of thin films significantly and second the use of bilayers that loosen the requirements of a single film at an interface.
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Bernabe, Gustau Catalan. "An investigation of functional properties in perovskite thin films." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343097.
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TURNER, ROBERT HAINES. "MOLECULAR STRUCTURE OF INTERFACES FORMED WITH PLASMA POLYMERIZED SILICA-LIKE PRIMER FILMS." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin997298644.
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Pang, Wenjie. "Synthesis and characterization of magnetic thin films--exchange bias systems." University of Western Australia. School of Physics, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0110.
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[Truncated abstract] Although exchange bias was discovered more than four decades ago, a satisfactory understanding of every instance of exchange bias observed in experiment has not yet emerged. Understanding exchange bias is complicated by many factors. For example, details of the antiferromagnet interface structure set up during the initial field cooling, thermal activation processes in the ferromagnet and antiferromagnet, and domain formation and domain wall movement in the antiferromagnet are all important in determining features associated with exchange bias. Two exchange bias systems are investigated in this thesis. One is a disordered system: a single layer Co/CoO film with random interfaces prepared by a reactive RF sputtering technique. The other is a ‘model’ system of Fe/KFeF 3 bilayers with compensated interfaces prepared by molecular beam epitaxy (MBE). The central theme of this work is to understand exchange bias and other related magnetic properties in these two very different systems. The Co/CoO exchange bias system studied here is different in structure from conventional exchange bias systems such as bilayer and multilayer systems where interfaces between ferromagnet and antiferromagnet are reasonably well defined. In this Co/CoO system, the Co and CoO is in the form of particles distributed randomly in a sputtered film. The interfaces between the Co and CoO are randomly distributed and may not be continuous over a large length scale. More importantly, the interface area is dependent on the shape and size of the particles and on their distribution. Many unique magnetic properties are related to the random interface in this system. For example, exchange bias and coercivity obtained at low temperatures are very large due to the large interface area between Co and CoO particles. The interface area can be controlled by changing the Co/CoO mass ratio in the film. Unlike in bilayer systems, film thickness in this single layer Co/CoO system turns out not to be critical for exchange bias and coercivity. The independence of film thickness may be technically important. More interestingly, because the interface is random, exchange bias can be setup by field cooling in any direction. Both training and magnetic viscosity effects were studied and provided evidence of thermal activation processes in this Co/CoO system. Training is explained as formation of a domain wall in the CoO with motion limited locally due to limited continuity of Synthesis and Characterization of Magnetic Thin Films - Exchange Bias Systems interfaces between the Co and CoO. Specific magnetization measurements over time were made and studied using viscosity theory. The magnetic viscosity was found to be strongly temperature dependent. There is a broad distribution of blocking temperatures which might be due to a broad distribution of Co particle sizes
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Martin, Justin J. "Construction of self-assembled inorganic interfaces as a method for tuning conducting polymer thin film sheet conductivity." Diss., Online access via UMI:, 2007.
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Siretanu, Igor. "Nanostructuration contrôlée de films de polymères." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14326/document.
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Il est bien connu que la structuration de surface dans la nature est très importante et ses applications très répandues. Des modèles simples, comme les vagues de surface, sont indispensables dans certains processus naturels et peuvent avoir une application directe aux innovations technologiques. Dans cette thèse, j'étudie les nouvelles méthodes de structuration et de processus de formation de structures contrôlées dans des films minces de polymères, en particulier à des températures inférieures à leur transition vitreuse. J'ai trouvé que la surface de polystyrène vitreux peut être reconstruite à température ambiante, par application directe ou indirecte d'un champ électrique, suggérant fortement qu’une couche de mobilité accrue existe à la surface de ce polymère vitreux. De plus grâce à cette thèse, nous présentons une nouvelle méthode pour induire et contrôler des structures submicroniques sur des substrats hydrophobes en une seule étape de traitement simple, basée sur le traitement du substrat avec une solution aqueuse dégazée. Cette nanostructuration est le résultat d'adsorption des espèces chargées proches sur la surface hydrophobe des polymères créant un champ électrique élevé, ce qui, combiné avec la mobilité de la surface du polymère, induit la déformation du substrat polymère. Comme l'étude directe des propriétés spécifiques de cette région, proche de la surface libre de films minces de polymères, est très rare en raison de la limite des techniques expérimentales appropriées, j'ai réalisé une étude approfondie de la relaxation temporelle des surfaces polymères préalablement structurées par les méthodes décrites ci-dessusIt is well known that the importance and the applications of surface structuration in Nature and in technology are widespread. Simple patterns, such as surface waves, are indispensable in some natural processes and may have direct application to technological innovations. In this thesis I investigate novel methods of structuring and control structure formation process in thin polymer films, particularly at temperatures lower than their glass transition. We have found that the surface of glassy polystyrene can be reconstructed at room temperature either by direct or indirect application of an electric field, strongly suggesting that a layer of enhanced mobility indeed exists at the surface of this glassy polymer. Additionally through this thesis we present a novel developed way to induce and control submicron structures on hydrophobic substrates by a single, simple treatment step based on treating the substrate with degassed aqueous solution. This nanostructuration is the result of close adsorption of charged species on the hydrophobic polymeric surface building a high electric field, which, combined with the mobility of the polymer surface, induces the deformation of the polymer substrate. Since, the direct study of properties of this specific near free surface region of thin polymer films is very rare due to the limited suitable experimental techniques; we have completed an extensive study of influence of supporting substrate and the temporal relaxation of previously polymer structured surfaces by above described methods
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Pugh, Peter Rupert Thomas. "Brillouin Light Scattering studies of magnetic thin films and multilayers." Thesis, University of Salford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365952.
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Liu, Boer. "THERMAL ANNEALING EFFECT ON UNENTANGLED STAR-SHAPED POLYSTYRENE RESIDUAL LAYER." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1525261861391343.
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Adams, Jonathan A. "A surface and interface study of aluminum selenide on silicon : growth and characterization of thin films /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/9797.
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Zai, Marvin Ho-Ming. "Chemical synthesis of lead zirconate titanate thin films for a piezoelectric actuator." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367760.
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Coux, González Patricia de. "Integration of ferrimagnetic CoFe2O4 epitaxial films with silicon." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/129162.
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El continuo progreso en microelectrónica se debe al crecimiento exponencial con el tiempo del número de transistores por circuito integrado, dependencia conocida como ley de Moore. Esta ley se sigue cumpliendo, pero se va acercando a límites intrínsecos. Por ello ha emergido la alternativa “More tan Moore”, un enfoque complementario basado en conceptos radicalmente nuevos y en la introducción de nuevos materiales que mejoren las prestaciones de dispositivos. En particular, los óxidos funcionales representan una buena oportunidad para incrementar y desarrollar las respuestas de dispositivos de interés para una gran gama de aplicaciones.
Esta tesis presenta un estudio sobre la integración de capas delgadas de CoFe2O4 sobre silicio. CoFe2O4 es ferromagnético y un aislante eléctrico a temperatura ambiente, que son las propiedades requeridas para ser utilizado como barrera túnel en un dispositivo de filtro de espín. Dicho dispositivo podría permitir la inyección de corrientes de espines polarizados en silicio, como alternativa a la inyección usando electrodos ferromagnéticos y barreras túneles pasivas. Sin obstante, un filtro de espín necesita una capa fina de CoFe2O4 de espesor nanométrico, inferior a 4-5 nm para permitir el efecto túnel, y una epitaxia de muy buena calidad para conservar el ferromagnetismo y el transporte por efecto túnel. La instabilidad termodinámica de CoFe2O4 con el silicio impone el uso de una capa barrera para su integración epitaxial. El mayor desafío reside en fabricar bicapas epitaxiales y extrafinas de CoFe2O4/barrera sobre silicio. El principal objetivo de esta tesis ha sido estudiar la posibilidad de realizar este objetivo.
La capa barrera es crucial. Hemos llevado a cabo una estrategia de investigación en paralelo considerando varios candidatos. SrTiO3, pudiendo crecer de forma epitaxial sobre Si(001) y ya usado como substrato monocristalino para el depósito de CoFe2O4, ha sido una opción evidente. Hemos usado capas búfer de SrTiO3 gruesas (alrededor de 17 nm) fabricadas por colaboradores del INL-Lyon para crecer capas de CoFe2O4 epitaxiales y ferromagnéticas mediante depósito con láser pulsado (pulsed laser deposition, PLD). Sin embargo hemos encontrado difusión detitanio en el CoFe2O4, y que la intercara de SrTiO3/Si(001) podría ser inestable.
Zirconia estabilizada con ítria (yttria-stabilized zirconia, YSZ) es otro óxido ampliamente usado como lámina barrera para la integración de óxidos sobre Si(001). Sin embargo siempre se usa siendo una barrera gruesa, con espesores de decenas de nanómetros y presentando una capa de SiOx en la intercara. Por ello hemos invesigado los mecanismos de crecimiento epitaxial de YSZ, con el fin de determinar los límites en la reducción de espesor de YSZ y de SiOx. Como resultado podemos obtener láminas barrera ultrafinas, de aproximadamente 2 nm de espesor y con menos de 1 nm de SiOx Ha sido posible usando PLD monitorizado con RHEED (reflection high energy electron diffraction). Usando estas láminas barrera, capas ultrafinas de CoFe2O4 epitaxiales presentan una orientación (111) y capas interfaciales de SiOx superiores a 2 nm de espesor. Aunque el resultado es remarcable, el espesor total de CFO/YSZ/SiOx es excesivo para un dispositivo de filtro de espín.
También hemos utilizado barreras de Sc2O3 y Y2O3 sobre Si(111), proporcionadas por colaboradores del IHP-Frankfurt Oder. Son candidatos originales que no se habían combinado nunca con CoFe2O4. A pesar del gran desajuste estructural con el CoFe2O4, de entre 15 y 20%, el crecimiento de CoFe2O4 es epitaxial. La caracterización por microscopia electrónica en transmisión ha mostrado un mecanismo de crecimiento epitaxial por ajuste dominios. Las capas presentan una magnetización cercana a la del material masivo y sin capa interfacial de SiOx en las heteroestructuras de CoFe2O4/Y2O3/Si(111). Las barreras de Y2O3 son por tanto prometedoras para la estructura nanométrica requerida en un filtro de espín. Hemos demostrado que barreras ultrafinas de Y2O3, con un espesor inferior a 2 nm, permiten el crecimiento epitaxial de CoFe2O4, aunque las investigaciones sobre la estabilidad de la intercara no han sido concluyentes.Microelectronics is progressing continuously by the exponential growth with time of the number of transistors per integrated circuit, the popularly known as “Moore’s Law”. This law is still valid but it is approaching intrinsic limits. The “More than Moore” is a complementary approach based on the use of radically new concepts as well as on the use of new materials in existing devices to improve performance. In particular, functional complex oxides represent an opportunity to extend and develop new devices functionalities with a wide range of applications. This thesis presents a study on the integration of CoFe2O4 thin films with silicon. CoFe2O4 is ferromagnetic and electrically insulating at room temperature, the properties required to be used as tunnel barrier in a spin filter device. This device could permit the injection of spin polarized currents in silicon, as an alternative to the injection using ferromagnetic electrodes and passive tunnel barriers. However the spin filter requires a nanometric CoFe2O4 film, thinner than 4-5 nm to allow tunneling, and has to be epitaxial with high crystalline quality to preserve the ferromagnetism and tunneling transport. The thermodynamical instability between CoFe2O4 and silicon imposes the use of a buffer layer for its epitaxial integration. The challenging goal is therefore fabricating ultrathin epitaxial CoFe2O4/buffer bilayers on silicon. Investigating the possibility to achieve such goal has been the main objective of this thesis. The buffer layer is critical. Thus we have followed a strategy based on investigating in parallel several candidates. SrTiO3, which can be grown epitaxially on Si(001) with sharp interface and that has been already used as single crystal to deposited CoFe2O4, has been a natural option. We have used thick (around 17 nm) SrTiO3 buffers fabricated by collaborators at INL-Lyon to grow by pulsed laser deposition (PLD) CoFe2O4, which is epitaxial and ferromagnetic. However, there is diffusion of Ti into CoFe2O4 and the SrTiO3/Si(001) interface could be unstable. Yttria-stabilized-zirconia (YSZ) has been other investigated material. It is widely used to grow oxides on Si(001), but having the YSZ buffershigh thickness of tens of nm and presence of interfacial SiOx. Here we have investigated the mechanisms of YSZ epitaxy to determine the limits reducing the YSZ thickness and the interfacial layer. Ultrathin buffers around 2 nm thick, with less than 1 nm thick SiOx layer, can be fabricated by reflection high energy electron diffraction (RHEED) assisted PLD. Ultrathin CoFe2O4 films subsequently grown were epitaxial, although (111) oriented and with the SiOx layers more than 2 nm thick. The result is remarkable, but the total thickness of CFO/YSZ/SiOx is excessive for a tunnel device. We have used also Sc2O3 and Y2O3 buffers on Si(111), provided by collaborators at IHP-Frankfurt Oder. They are original candidates never combined with CoFe2O4. In spite of the huge lattice mismatch of around 15 and 20% CoFe2O4 grows epitaxially. Detailed transmission electron microscopy (TEM) has showed a mechanism of domain matching epitaxy. The films present magnetization close to the bulk value and without interfacial SiOx layer in the CoFe2O4/Y2O3/Si(111) sample. Thus Y2O3 appear as very promising buffer layer and maybe convenient for the nanometric structure required in a spin filter. We have demonstrated that ultrathin Y2O3 buffers, less than 2 nm thick, permit epitaxial growth of CoFe2O4, although the investigation of the interface stability has not been conclusive.
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Carlomagno, Ilaria. "L'origine de la réponse magnétique particulière des films minces de Co intercalés entre Graphene et Ir(111)." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY025/document.
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Le sujets de cette thèse sont l'évolution structurelle et la réponse magnétique particulière des films de cobalt observés lors de l'intercalation entre graphène et Ir (111).L'origine du comportement magnétique exotique de ces films n'a pas été trouvée encore. À cet égard, l'objectif final de ce travail est de sonder les effets de l'anisotropie structurale sur l'anisotropie magnétique.Plusieurs paramètres tels que l'épaisseur du film, les temps et les températures de la procedure du textit{annealing}, la présence de graphène et l'environnement local de Co ont été pris en compte comme possibles sources d'anisotropie structurale.Une analyse complète a été réalisée en utilisant des techniques complémentaires et avancées. Techniques comme la spectroscopie de photoélectrons de rayons X (XPS) et l'effet Kerr magnéto-optique (MOKE) ont fourni des informations sur la distribution de Co dans la direction perpendiculaire à la surface et sur la réponse magnétique. Cependant, techniques de rayonnement synchrotron comme la spectroscopie d'absorption de rayonnement X (XAS) et la diffraction de rayons X par incidence rasante (GIXD) ont sondé la structure locale et l'ordre à long terme des films.L'analyse présentée dans cette thèse inclut les effets de surface à l'interface Co/Ir, l'environnement local autour du Co, la structure cristalline du film, la rugosité du système et le désordre moyen.En particulier, l'évolution de ces paramètres est présentée et discutée en même temps que leur effet sur la réponse magnétique macroscopique des films intercalés.Les résultats démontrent que les traitements thermiques affectent la morphologie du Co, sa rugosité et sa coordination locale. Tels effets altèrent la structure du film affectant l'anisotropie magnétique globale. Cette information est utile à des fins applicatives. De plus, la description des modifications micro-structurales fournit un aperçu approfondi des propriétés physiques des films de Co intercalésThis thesis focuses on the structural evolution and the peculiar magnetic response of Cobalt films observed upon intercalation between Graphene and Ir(111).The origin of the exotic magnetic behaviour of such films cite{ROUGEMAILLE} has not been found yet. In this respect, the final goal of this work is to probe the effects of the structural anisotropy on the magnetic anisotropy.Several parameters such as: film thickness, annealing times and temperatures, Graphene presence, and Co local environment were taken into account as possible sources of structural anisotropy.A complete analysis was carried out using complementary, state-of-the-art techniques. While laboratory techniques such as X-ray Photoelectron Spectroscopy (XPS) and Magneto-Optic Kerr Effect (MOKE) provided information on the Co distribution along the direction perpendicular to the surface, and on the magnetic response, synchrotron radiation techniques such as X-ray Absorption Spectroscopy (XAS) and Grazing Incidence X-ray Diffraction (GIXD) probed the local structure and the long range order of the films.The analysis presented in this thesis includes the surface effects at the Co/Ir interface, the local Co environment, the crystalline structure of the film and the system roughness and average disorder.In particular, the evolution of such parameters is presented and discussed together with their effect on the macroscopic magnetic response of the intercalated films.The results demonstrate that thermal treatments affect Co morphology, roughness, and local coordination. Such effects alter the film structure affecting the overall magnetic anisotropy. This information alone is valuable for applicative purposes. Moreover, the description of the micro-structural modifications provides a deep insight into the physical properties of intercalated Co films
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Wang, Dong [Verfasser]. "Fatigue behavior of thin Cu films : film thickness and interface effects / Dong Wang." Karlsruhe : Forschungszentrum Karlsruhe, 2007. http://d-nb.info/98578797X/34.
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Wallin, Erik. "Alumina Thin Films : From Computer Calculations to Cutting Tools." Doctoral thesis, Linköpings universitet, Plasma och beläggningsfysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15360.
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The work presented in this thesis deals with experimental and theoretical studies related to alumina thin films. Alumina, Al2O3, is a polymorphic material utilized in a variety of applications, e.g., in the form of thin films. However, controlling thin film growth of this material, in particular at low substrate temperatures, is not straightforward. The aim of this work is to increase the understanding of the basic mechanisms governing alumina growth and to investigate novel ways of synthesizing alumina coatings. The thesis can be divided into two main parts, where the first part deals with fundamental studies of mechanisms affecting alumina growth and the second part with more application-oriented studies of high power impulse magnetron sputter (HiPIMS) deposition of the material. In the first part, it was shown that the thermodynamically stable α phase, which normally is synthesized at substrate temperatures of around 1000 °C, can be grown using reactive sputtering at a substrate temperature of merely 500 °C by controlling the nucleation surface. This was done by predepositing a Cr2O3 nucleation layer. Moreover, it was found that an additional requirement for the formation of the α phase is that the depositions are carried out at low enough total pressure and high enough oxygen partial pressure. Based on these observations, it was concluded that energetic bombardment, plausibly originating from energetic oxygen, is necessary for the formation of α-alumina (in addition to the effect of the chromia nucleation layer). Moreover, the effects of residual water on the growth of crystalline films were investigated by varying the partial pressure of water in the ultra high vacuum (UHV) chamber. Films deposited onto chromia nucleation layers exhibited a columnar structure and consisted of crystalline α-alumina if deposited under UHV conditions. However, as water to a partial pressure of 1*10-5 Torr was introduced, the columnar α-alumina growth was disrupted. Instead, a microstructure consisting of small, equiaxed grains was formed, and the γ-alumina content was found to increase with increasing film thickness. To gain a better understanding of the atomistic processes occurring on the surface, density functional theory based computational studies of adsorption and diffusion of Al, O, AlO, and O2 on different α-alumina (0001) surfaces were also performed. The results give possible reasons for the difficulties in growing the α phase at low temperatures through the identification of several metastable adsorption sites and also show how adsorbed hydrogen might inhibit further growth of α-alumina crystallites. In addition, it was shown that the Al surface diffusion activation energies are unexpectedly low, suggesting that limited surface diffusivity is not the main obstacle for low-temperature α-alumina growth. Instead, it is suggested to be more important to find ways of reducing the amount of impurities, especially hydrogen, in the process and to facilitate α-alumina nucleation when designing new processes for low-temperature deposition of α-alumina. In the second part of the thesis, reactive HiPIMS deposition of alumina was studied. In HiPIMS, a high-density plasma is created by applying very high power to the sputtering magnetron at a low duty cycle. It was found, both from experiments and modeling, that the use of HiPIMS drastically influences the characteristics of the reactive sputtering process, causing reduced target poisoning and thereby reduced or eliminated hysteresis effects and relatively high deposition rates of stoichiometric alumina films. This is not only of importance for alumina growth, but for reactive sputter deposition in general, where hysteresis effects and loss of deposition rate pose a substantial problem. Moreover, it was found that the energetic and ionized deposition flux in the HiPIMS discharge can be used to lower the deposition temperature of α-alumina. Coatings predominantly consisting of the α phase were grown at temperatures as low as 650 °C directly onto cemented carbide substrates without the use of nucleation layers. Such coatings were also deposited onto cutting inserts and were tested in a steel turning application. The coatings were found to increase the crater wear resistance compared to a benchmark TiAlN coating, and the process consequently shows great potential for further development towards industrial applications.
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Tumakha, Serhii. "Investigation of 4H and 6H-SIC thin films and schottky diodes using depth-dependent cathodoluminescence spectroscopy." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1138202968.
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Frey, Natalie A. "Surface and interface magnetism in nanostructures and thin films." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002434.
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Roychoudhury, Rajat. "Growth and characterization of phosphorus doped diamond films : effects of doping, electrical characterization of interfaces and some device applications /." free to MU campus, to others for purchase, 1997. http://wwwlib.umi.com/cr/mo/fullcit?p9841331.
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Garza, Michelle. "Reactivity of Oxide Surfaces and Metal-Oxide Interfaces: Effects of Water Vapor Pressure on Ultrathin Aluminum Oxide Films, and Studies of Platinum Growth Modes on Ultrathin Oxide Films and Their Effects on Adhesion." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4517/.
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The reactivity of oxide surfaces and metal-oxide interfaces play an important role in many technological applications such as corrosion, heterogeneous catalysis, and microelectronics. The focus of this research was (1) understanding the effects of water vapor exposure of ultrathin aluminum oxide films under non-ultrahigh vacuum conditions (>10-9 Torr) and (2) characterization of Pt growth modes on ultrathin Ta silicate and silicon dioxide films and the effects of growth modes on adhesion of a Cu overlayer. These studies were conducted with X-ray photoelectron spectroscopy (XPS). Ni3Al(110) was oxidized (10-6 Torr O2, 800K) followed by annealing (1100K). The data indicate that the annealed oxide film is composed of NiO, Al2O3 and an intermediate phase denoted here as "AlOx". Upon exposure of the oxide film at ambient temperature to increasing water vapor pressure (10-6 - 5 Torr), a shift in both the O(1s) and Al(2p)oxide peak maxima to lower binding energies is observed. In contrast, exposure of Al2O3/Al(polycrystalline) to water vapor under the same conditions results in a high binding energy shoulder in the O(1s) spectra which indicates hydroxylation. Spectral decomposition provides further insight into the difference in reactivity between the two oxide films. The corresponding trends of the O(1s)/Ni0(2p3/2) and Al(2p)/Ni0(2p3/2) spectral intensity ratios suggest conformal changes of the oxide film on Ni3Al(110). The growth behavior of sputter deposited Pt at ~300K on Ta silicate and SiO2 ultrathin films formed on Si(100) was investigated. The XPS data show that Pt deposition results in uniform growth or "wetting" on Ta silicate and 2-D cluster growth on SiO2. Electroless Cu deposition on ~11 monolayers (ML) Pt/Ta silicate film results in an adherent Cu film which passed the Scotch tape test. In contrast, electroless Cu deposition on ~11ML Pt/SiO2 results in a non-adherent Cu film due to weak Pt/SiO2 interaction.
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Lidbaum, Hans. "Transmission Electron Microscopy for Characterization of Structures, Interfaces and Magnetic Moments in Magnetic Thin Films and Multilayers." Doctoral thesis, Uppsala universitet, Experimentell fysik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-107941.
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Structural characterization is essential for the understanding of the magnetic properties of thin films and multilayers. In this thesis, both crystalline and amorphous thin films and multilayers were analyzed utilizing transmission electron microscopy (TEM). High resolution TEM and electron diffraction studies emphasize on the growth of amorphous Fe91Zr9 and Co68Fe24Zr8 on both Al2O3 and Al70Zr30 in multilayer structures by magnetron sputtering. The properties of the growth surfaces were found to strongly influence the formation of nano-crystallites of the magnetic material at interfaces. Field induced uniaxial magnetic anisotropy was found to be possible to imprint into both fully amorphous and partially crystallized Co68Fe24Zr8 layers, yielding similar magnetic characteristics regardless of the structure. These findings are important for the understanding of both growth and magnetic properties of these amorphous thin films. As magnetic systems become smaller, new analysis techniques need to be developed. One such important step was the realization of electron energy-loss magnetic circular dichroism (EMCD) in the TEM, where information about the ratio of the orbital to spin magnetic moment (mL/mS) of a sample can be obtained. EMCD makes use of angular dependent inelastic scattering, which is characterized using electron energy-loss spectroscopy. The work of this thesis contributes to the development of EMCD by performing quantitative measurements of the mL/mS ratio. Especially, methods for obtaining energy filtered diffraction patterns in the TEM together with analysis tools of the data were developed. It was found that plural inelastic scattering events modify the determination of the mL/mS ratio, wherefore a procedure to compensate for it was derived. Additionally, utilizing special settings of the electron gun it was shown that EMCD measurements becomes feasible on the nanometer level through real space maps of the EMCD signal.
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Chen, Min [Verfasser], and J. Michael [Akademischer Betreuer] Gottfried. "Surface-Assisted Chemistry at Interfaces between Metals and Organic Thin Films / Min Chen. Betreuer: J. Michael Gottfried." Marburg : Philipps-Universität Marburg, 2016. http://d-nb.info/1097534634/34.
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Trenkmann, Ines, Daniela Täuber, Michael Bauer, Jörg Schuster, Sangho Bok, Shubhra Gangopadhyay, and Christian von Borczyskowski. "Investigations of solid liquid interfaces in ultra-thin liquid films via single particle tracking of silica particles." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-191734.
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Single particle tracking with a wide field microscope is used to study the solid liquid interface between the viscous liquid tetrakis(2 ethylhexoxy)-silane and a silicon dioxide surface. Silicon dioxide nanoparticles (5 nm diameter) marked with the fluorescent dye rhodamine 6G are used as probes. The distributions of diffusion coefficients, obtained by mean squared displacements, reveal heterogeneities with at least two underlying diffusion components. Measurements on films with varying film thicknesses show that the slower component is independent of the film thickness, while the faster one increases with the film thickness. Additionally, we could show that the diffusion behavior of the particles cannot be sufficiently described by only two diffusion coefficients.
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Trenkmann, Ines, Daniela Täuber, Michael Bauer, Jörg Schuster, Sangho Bok, Shubhra Gangopadhyay, and Christian von Borczyskowski. "Investigations of solid liquid interfaces in ultra-thin liquid films via single particle tracking of silica particles." Diffusion fundamentals 11 (2009) 108, S. 1-12, 2009. https://ul.qucosa.de/id/qucosa%3A14082.
Full textAbstract:
Single particle tracking with a wide field microscope is used to study the solid liquid interface between the viscous liquid tetrakis(2 ethylhexoxy)-silane and a silicon dioxide surface. Silicon dioxide nanoparticles (5 nm diameter) marked with the fluorescent dye rhodamine 6G are used as probes. The distributions of diffusion coefficients, obtained by mean squared displacements, reveal heterogeneities with at least two underlying diffusion components. Measurements on films with varying film thicknesses show that the slower component is independent of the film thickness, while the faster one increases with the film thickness. Additionally, we could show that the diffusion behavior of the particles cannot be sufficiently described by only two diffusion coefficients.
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Maccarini, Marco. "Surface and interface properties of industrially relevant polymers." Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251284.
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