Dissertations / Theses on the topic 'Thin films – Analysis'
To see the other types of publications on this topic, follow the link: Thin films – Analysis.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Thin films – Analysis.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Miller, James R. "Analysis of rectifying molecular thin films." Thesis, Cranfield University, 2005. http://dspace.lib.cranfield.ac.uk/handle/1826/10445.
Full textAbstract:
The
mercury-drop electrode technique, when used to measure the current/voltage
characteristics of thin films of molecular rectifiers, is a useful, if awed method of
analysis. Current/voltage plots taken from a number of samples confirm previous
studies taken using the scanning tunnelling microscope (STM), but indicate significant
levels of
penetration of the mercury into the sample or stabilising monolayer. Quartz
crystal microbalance (QCM) studies of the adsorption of 7,7,8,8°-
tetracyanoquinodimethane (TCNQ) onto clean gold indicate small but significant
adsorption, with possible formation of a salt, via conversion of TCNQ into the radical
anion. This has
implications for the results of previous experiments, which indicate
alternative sources for the rectification observed from donor-bridge-acceptor systems,
but also
suggest use of the TCNQ radical anion as a electron donor when used to
replace the counterion present in a number of self-assembled systems. Previous STM-
based measurements confirming this latter suggestion are supported by mercury-drop
studies. The results
support conclusions previously drawn by a number of authors,
removing much of the ambiguity surrounding their interpretation, whilst clarifying the
adsorption characteristics of thiol-based molecules that contain a terminal TCNQ group,
and to some extent, TCNQ itself. It is suggested that the mercury-drop technique should
never be used in isolation to
quantify rectification in monolayers of molecular rectifiers,
but that it is suitable for use only i confirming and checking results from more
established procedures.
2
Pasupuleti, Ajay. "Analysis of effective mechanical properties of thin films used in microelectromechanical systems /." Online version of thesis, 2007. http://hdl.handle.net/1850/5283.
Full text
3
Sullivan, Brian Thomas. "Spectroscopic ellipsometry of Palladium thin films." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/27546.
Full textAbstract:
Spectroscopic ellipsometry is a nondestructive, ambient surface analysis technique for studying surfaces, interfaces and thin films. To take advantage of this method an automatic spectroscopic ellipsometer was designed and constructed for the microstructural characterization of thin films. This high precision instrument is capable of measuring in real-time the optical properties of bulk or thin film materials over the visible-UV region (1.5 - 6.0 eV). The microstructure of thin films can be determined from an effective medium theory analysis of the spectroellipsometric data to investigate how the film morphology evolves with varying preparation conditions and to determine the optimum deposition parameters.
In this thesis the pseudodielectric function of palladium films prepared by dc planar magnetron sputtering was measured while the substrate temperature, argon partial pressure and rf-induced substrate bias were varied independently during deposition. The film data are in excellent agreement with the effective medium theory of Sen, Scala, and Cohen, relevant for a random coated-particle microstructure where the grains are optically isolated from each other.
With increasing substrate temperature, the Pd volume fraction in the bulk was found to decrease slightly, while the rms microroughness of the film surface increased in magnitude. At 190° C, the rms microroughness was 80 ± 3 Awith the Pd volume fraction in the bulk region falling slightly to 97 ± 1% relative to the film deposited at 22° C.
For argon partial pressures below a transition pressure, Pt≃15 mTorr, the films consisted of densely packed grains, corresponding to the zone T in Thornton's structure zone model. Above this transition pressure, the films developed into a more voided columnar structure, characteristic of the zone 1 region. A microstructural analysis indicated a general trend towards increased porosity and microroughness of the films with higher argon pressures. The zone 1 region was best described optically by a random coated-particle microstructure and the electron microscopy confirmed that for thin films prepared at argon pressures higher than Pt, the grains became isolated by void boundaries. The optical data could not distinguish whether or not the films were 2- or 3-dimensionally isotropic.
With increasing rf-induced substrate biasing, the Pd film microstructure was modified in a manner similar to that obtained by varying the substrate temperature alone. Significant resputtering of the Pd films occurred, varying from 2 to 11 A/sec for bias voltages of -550 V to -1375 V, respectively. The measured deposition rate while bias sputtering was significantly higher than that expected upon the measured resputtering rate and several mechanisms were proposed to account for the enhancement in the deposition rate. The films were best characterized by a 2-dimensional isotropy which was supported by the columnar nature of the films observed by electron microscopy.
Finally, the dielectric function of the "best" palladium film is compared to optical constants of Pd previously reported in the literature for bulk and thin film specimens. While all the authors quote essentially the same values for the real part of the dielectric function, regardless of the preparation or measurement technique, the imaginary part differs up to a factor of two. Surface microroughness, bulk porosity and oxide layers are unable to account for the difference. A possible grain boundary scattering mechanism is suggested.Science, Faculty of
Physics and Astronomy, Department of
Graduate
4
Sánchez, Rodríguez Daniel. "Obtaining advanced oxide thin films at low temperatures by chemical methods. Thermal analysis of thin films." Doctoral thesis, Universitat de Girona, 2015. http://hdl.handle.net/10803/328723.
Full textAbstract:
L'objectiu d'aquest treball és analitzar mètodes químics de baix cost com a ruta per a sintetitzar òxids avançats a baixa temperatura. En particular, hem explorat l'SHS per a la síntesi d'un òxid catalitzador fent servir pólvores de ciano complexes heteronuclears. També hem explorat el transport de calor per a sintetitzar capes via VCS concloent que les capes primes rarament experimentaran una combustió. Per això hem analitzat la condició necessària per que tingui lloc una combustió volumètrica en una mostra sòlida que reacciona sense intercanvi de gasos amb el seu entorn. Per fer-ho, hem ampliat el criteri de Frank-Kaminetskii per a sistemes d'escalfament continu i per a reactors cilíndrics. Per la part experimental em fet servir tècniques l'anàlisi tèrmica (TA). Hem desenvolupat un mètode per a mesurar la conductivitat tèrmica en pólvores per DSC. Finalment, hem desenvolupat dos criteris per a comprovar la fiabilitat en la mesura de la temperatura als experiments de TA.The aim of this work is to analyse chemical methods as a route to synthesise advanced oxides at low cost and low temperatures. In particular, we have explored the combustion synthesis of a catalytic perovskite-type oxide from heteronuclear cyano complex powders. We have also explored heat transfer to synthesise films via VCS and concluded that thin films will hardly experience combustion. In particular, we have analysed the conditions needed for a thermal explosion to occur in a solid sample reacting without any gas exchange with its surroundings. For that purpose, we have extended the Frank-Kamenetskii relationship to continuous heating systems and to cylindrical reactors. The experimental component of this work is based on thermal analysis methods (TA). We have developed a new method to measure thermal conductivity of powders by DSC. Finally, we have developed two analytical relationships to check the reliability of the sample temperature in TA experiments.
5
Hickey, Carolyn Frances. "Optical, chemical, and structural properties of thin films of samarium-sulfide and zinc-sulfide." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184263.
Full textAbstract:
The development of materials for optical thin film application is essential to progress in fields such as optical data storage and signal processing. Samarium sulfide (SmS) thin films were prepared by reactive evaporation of samarium in hydrogen sulfide (H₂S). These displayed optical switching properties despite the presence of large amounts of carbon and oxygen. They are therefore potentially useful for data storage. The semiconductor to metal phase transition was characterized by x-ray diffraction and spectrophotometry. The observed optical response was modelled by a Bruggeman effective medium calculation. Success with this analysis suggests it as a means for predicting performance in subsequent applications. Zinc sulfide (ZnS) thin films were prepared by molecular beam epitaxy (MBE). Implimentation of an H₂S treated silicon surface provided good chemical bond match in addition to a good lattice match. Atomic layer epitaxy was unsuccessfully explored as a means to grow ZnS from zinc and H₂S reactants, therefore other reactants are proposed. Both the MBE and ALE work is directed at the long term goals of producing p-type ZnS, which is suitable for semiconductor lasing at short wavelengths, and high quality SmS thin films.
6
Mauthoor, Soumaya. "Structural analysis of molecular nanostructures and thin films." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6362.
Full textAbstract:
Phthalocyanines (Pcs) form crystals whose structure and morphology depend on the growth conditions, leading to changes in the physical properties which are still little understood. Pc thin films and nanostructures have already been exploited in optoelectronic applications and could form the basis of spintronic devices but little or contradictory structural information is available because they are challenging systems to study. Hence the precise determination of the molecular order in these systems is of considerable interest both from a fundamental and technological point of view but requires a combination of complementary techniques. Crystalline powders of α-copper phthalocyanine (CuPc), α-metal-free phthalocyanine (H2Pc) and their mixtures are studied using powder X-ray diffraction (XRD) and found to be isomorphous and adopt a triclinic structure first proposed for α-CuPc (Hoshino et al., 2003). This information is used to study highly textured crystalline α-Pc thin films. The texture reduces the available crystallographic information but allows for the manipulation of the anisotropic physical properties. The Pc molecular plane lies 82±11° to the substrate when deposited on a weakly interacting substrate but at 7 or 9±5° when templated by a layer of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA). Such an interpretation is different to all those previously given. The change in the texture is confirmed by high resolution transmission electron microscopy (HRTEM) of ultramicrotomed cross-sections of the films. The optimum TEM operating conditions were first determined on sections of CuPc single crystals which demonstrated an information limit of ~5Å with HRTEM. The technique was then applied to the films and the morphology, crystallinity and texturing of the layers is largely retained by the sectioning process. With further refinements it is hoped that this technique could be used to study the properties of interfaces and individual domains in multilayers and blends of organic thin films. Lastly the crystal structure of a new CuPc phase designated as η which forms nanowires as thin as 10nm and shows enhanced absorption in the infra-red (IR) is proposed. XRD, transmission electron diffraction (TED) and lattice potential energy (LPE) minimisation were used to determine the crystal structure: monoclinic P21/a, Z = 2, a = 24.8±0.2Å, b = 3.77±0.02Å, c = 13.2±0.1Å and β = 106±1°. The LPE minimisation was validated by correctly predicting the atomic coordinates of β-CuPc to within 0.05Å.
7
Craib, Glenn R. G. "Thin film structural determination and surface analysis." Thesis, University of Aberdeen, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320771.
Full textAbstract:
A combined approach to the use of surface analysis techniques and X-ray diffraction has been introduced. In particular the development of the microstructure of UHV evaporated thin metallic films has been investigated with a view to clarifying influences on microstructure (particularly texture). This study has shown the wide range of experimental parameters which affect the final film structure, such as temperature, oblique incidence and substrate roughness. An automated energy dispersive X-ray diffractometer has been developed for the study of thin film texture. The required corrections for loss of intensity due to sample positioning have been developed and verified. Pole figures have been collected for erbium and nickel thin films (thickness 200-1200 nm) grown on molybdenum or glass substrates. Results for the erbium films show a substantial effect on the texture of the film, contributed by the temperature of the substrate during deposition. The texture varies from mixed fiber at low temperature, to a strong single fiber orientation at around 663 K, to mixed fiber at higher temperatures. The strong orientation at 663 K has been shown to vary from either (002) to (101) depending on as yet unknown experimental conditions. The effect of substrate roughness appears to be only in the degree of orientation and it does not affect the overall nature of the texture of the film. The texture of the nickel films shows a form of "granular epitaxy" at substrate temperatures above 300 K. The presence of tensile stress within one of these nickel thin film samples has been determined and is interpreted to give support to a proposed mode of granular epitaxy.
8
Cotier, Bradley Neville. "Fullerene nanostructures, monolayers and thin films." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342471.
Full text
9
Riedle, Thomas. "Raman spectroscopy for the analysis of thin CuInS2 films." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=964986388.
Full text
10
Smith, Alastair. "Cavity enhanced spectroscopy methods for analysis of thin films." Thesis, University of Bristol, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443666.
Full text
11
Severtson, Yuan C. "Stability analysis of thin film coating systems." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/17965.
Full text
12
Zeybek, Orhan. "Surface studies of magnetic thin films." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367247.
Full text
13
Gignac, Lynne Marie. "Processing and characterization of RF sputtered alumina thin films." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184611.
Full textAbstract:
Thin films of alumina were deposited on ferrite (NiₓZn₍₁₋ₓ₎Fe₂O₄), glass, single crystal silicon and graphite substrates by RF sputtering. Though standard, amorphous Al₂O₃ films are readily soluble in hot phosphoric acid, these sputtered films exhibited only reluctant etchability by the acid. Experiments were initially performed to understand the parameters in the sputtering process which were influential in the formation of unetchable films. The results showed that a high concentration of water vapor or oxygen molecules in the sputtering chamber during deposition was the most significant variable controlling the growth of unetchable films. The films were categorized according to their degree of solubility in H₃PO₄ and were examined using various microanalytical characterization techniques. TEM analysis directly showed the existence of crystalline γ-Al₂O₃ in the film at the film-substrate interface. The γ-Al₂O₃ phase grew with a preferred orientation coincident with the substrate orientation--as in heteroepitaxial growth. The occurrence of this film phase was related to the oxygen partial pressure, the substrate material, and the substrate temperature and was believed to be the cause of the film's incomplete etching behavior.
14
Sriram, K. "A Finite Element Investigation Of Brittle Fracture During Spherical Nanoindentation Of Thin Hard Films." Thesis, Indian Institute of Science, 2001. http://hdl.handle.net/2005/252.
Full textAbstract:
Hard ceramic films of micrometric thickness deposited on a soft metallic substrate have ushered in a new era in the fabrication of structural, tribological, microelectronic and optical components. The mechanical performance of these components is however critically dependent on the strength and toughness of these films as well as on those of the film-substrate interface. Recent studies have shown that cylindrical and radial cracks can propagate through the film during nanoindentation tests with spherically tipped and pointed indenters, resulting in steps in the load versus displacement curve. In this thesis, the mechanics of fracture of thin hard films bonded to soft substrates, during nanoindentation is studied by carrying out finite element analyses. The role of plastic yielding in the substrate on the above issue is examined. Another important objective of this work is to propose a method by which finite element simulations can be employed to interpret nanoindentation test results and yield information related to the fracture behaviour of hard films.
To this end, axisymmetric finite element analyses of spherical nanoindentation of a TiN film of thickness t = 1 //m, on a steel substrate are carried out. Numerical algorithms for large deformation, contact simulation and computation of energy release rate are employed in the analyses. The film is assumed to be linear elastic, whereas, an elastic-plastic constitutive model is used for the substrate.
A nanoindentation analysis of the uncracked film is first carried out. The development of plastic yielding in the substrate and its influence on the load P versus penetration h characteristics is examined. The stress fields around the indenter for different depths of indentation are studied. The results show that the radial stress attains a tensile peak at the film surface, just outside the indented zone. However, it becomes compressive with increasing distance below the surface. Interestingly, a tensile radial stress prevails at the film-substrate interface at large indentation depth. The shear stress increases to a peak value at a distance of 0.052 to OAt below the film surface depending upon the radial location and then reduces.
Next, circumferential cracks extending downwards from the film surface are introduced at different radial distances R from the axis of symmetry. Finite element analyses are carried out till the indented zone extends almost up to the crack surface. The energy release rate J is computed as a function of indentation depth for different
crack lengths c (in the range from O.lt to 0.9t). The results show that shallow cracks are essentially under Mode II loading with closure of crack faces caused by compressive radial stresses. However, a mixed-mode state prevails if the crack length is large (c > 0.62), with crack faces opening out due to tensile radial stress near the film-substrate interface. The variation of J with c/t for cracks located at different radial distances R is examined. It is found that for small R, there is a decreasing branch in the J versus c variation between c = 0.2i to 0.75£ which indicates that crack extension in this range will be stable. On the other hand, for large R, J increases monotonically with c/t which implies that unstable fracture of the full film thickness will occur following crack initiation.
A composite nomogram is generated in the P — h plane where constant J lines are plotted along with load-displacement curves for different crack lengths. If now a nanoindentation (experimental) load-displacement behaviour is superimposed on this nomogram, the initial crack length (of a pre-existing flaw), the final crack length and fracture energy of the film can be inferred.
In the last part of the thesis, the effect of the substrate yield strength on the indentation mechanics is studied. It is found that upon decreasing the yield strength, the load at a given indentation depth decreases while the residual depth at unloading increases. Also, the energy release rate for a given radial location and crack length reduces considerably at large depths of indentation.
15
Huang, Pao-Cheng. "Analysis of single-crystal semiconductor thin film structure by x-ray diffraction." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/20145.
Full text
16
Clarke, John. "X-ray scattering from thin films and interfaces." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4499/.
Full textAbstract:
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.
17
Lau, Chi Hian. "Chemical, electronic and electrochemical properties of diamond thin films." Thesis, University of Oxford, 2002. http://ora.ox.ac.uk/objects/uuid:53a0886c-14ad-431a-975d-0ecca8fc8968.
Full textAbstract:
Diamond is of interest as an advanced functional material, since the extreme physical properties of diamond, suggests it is ideally suited to a range of new demanding applications. In this context, the thesis explores basic surface chemical properties of diamond thin films, along with electrochemical, electronic and electron emission processes involving this material. New experiments are reported concerning the nature of surface conductivity on diamond. Measurements clearly show that the conductivity only arises if a hydrogenated diamond surface is exposed to water vapour, in the presence of chemical species capable of acting as electron acceptors. The conduction properties of surface conductive diamond in aqueous solution are also studied, and the first detailed electrochemical investigations of this material are described. Comparative electrochemical studies of nanocrystalline and boron-doped diamond have been performed. Investigations of electrode stability, and the accessible "potential window" are described, as well as the behaviour of a range of 'redox' systems, including transition metal complexes, metal deposition/stripping, and bio-related organic species. Significant differences between the behaviour of nanodiamond and microcrystalline boron-doped material are observed. A range of surface chemical and threshold photoemission studies of diamond thin films are reported. The results indicate that quantum photoyields (QPYs) are insensitive to the diamond "quality", although the wavelength selectivity is dependent on it. The adsorption of oxygen strongly reduces the QPY, although this only occurs slowly in the presence of O2 because of a low reactive sticking probability. Much more rapid uptake of oxygen and consequent reduction of photoyield is observed in the presence of atomic O or electronically excited dioxygen O2*. The presence of alkali metals on the diamond surface increases the QPY, and reduces the sensitivity of the QPY to surface oxygen. Significant differences between the surface chemical properties of Li, and other adsorbed akali metals (K and Cs) are observed.
18
Kumar, Atul. "Diffraction stress analysis of thin films; investigating elastic grain interaction." Stuttgart Max-Planck-Inst. für Metallforschung, 2005. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-24805.
Full text
19
Spargo, Adam W. "Finite element analysis of magnetization reversal in granular thin films." Thesis, Bangor University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273665.
Full text
20
Canli, Sedat. "Thickness Analysis Of Thin Films By Energy Dispersive X-ray Spectroscopy." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612822/index.pdf.
Full textAbstract:
EDS is a tool for quantitative and qualitative analysis of the materials. In electron microscopy, the energy of the electrons determines the depth of the region where the X-rays come from. By varying the energy of the electrons, the depth of the region where the X-rays come from can be changed. If a thin film is used as a specimen, different quantitative ratios of the elements for different electron energies can be obtained. Unique thickness of a specific film on a specific substrate gives unique energy-ratio diagram so the thickness of a thin film can be calculated by analyzing the fingerprints of the energy-ratio diagram of the EDS data obtained from the film.
21
Wu, Chen. "Elemental growth of oxide thin films." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:ac82a52f-bb62-41d0-a604-3cf7a95e5aaf.
Full textAbstract:
This thesis reports on the elemental growth of oxide thin films including TiOx, BaOx and BaxTiyOz by Ti/Ba deposition and oxidation. The films were grown on two different substrates, Au(111) and SrTiO₃(001), and studied using a variety of surface characterisation techniques. On the reconstructed Au(111) surface, three different TiOx structures were obtained with increasing Ti amounts deposited: a (2 × 2) Ti₂O₃ honeycomb structure, a pinwheel structure that is the result of a Moiré pattern, and a triangular island TiO1.30 structure. The structures arise from raised Ti coverages and have increased Ti densities. Although Ba deposited on the reconstructed Au(111) has a weak interaction with the substrate, the BaOx thin films can grow epitaxially and lift the Au(111) reconstruction. Two well-ordered phases, a (6 × 6) and a (2√3 × 2√3) BaOx structure, were obtained which may have octopolar-based surface structures. For Ba & Ti deposition on Au(111), a locally ordered (5 × 5) BaxTiyOz structure was observed in the sub-monolayer regime. What is more interesting is the possible formation of a BaO-TiO surface alloy with short-range ordering achieved by Ba deposition on the (2 × 2) Ti₂O₃-templated Au(111) surface. This is the first time that surface-alloying has been observed for oxides. When Ti is deposited onto the SrTiO₃(001) surface, it is incorporated into the substrate by forming a variety of Ti-rich SrTiO₃ surface reconstructions, such as c(4 × 2), (6 × 2), (9 × 2) and (√5 ×√5)-R26.6°. Ti deposition provides a completely different route to obtaining these reconstructions at much lower anneal temperatures than the previously reported preparation procedures involving sputtering and annealing the SrTiO₃ sample. Anatase islands with (1 × 3) and (1 × 5) periodicities were also formed by increasing the Ti deposition amount and post-annealing. Reconstructed SrTiO₃ substrate surface has a lattice that differs from the bulk crystal and affects the epitaxial growth of BaO, however, a locally ordered BaOx structure was observed on the sputtered substrate with a growth temperature of 300 °C. Depositing Ba & Ti on SrTiO₃(001) results in the formation of BaOx clusters and the Ti incorporation into the substrate, forming the familiar Ti-rich SrTiO₃ surface reconstructions.
22
Krus, David Jr. "Finite element analysis of thin film mechanical properties." Case Western Reserve University School of Graduate Studies / OhioLINK, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=case1059745475.
Full text
23
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.
Full text
24
Li, Zuoli. "Studies of Thin Liquid Films Confined between Hydrophobic Surfaces." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/49557.
Full textAbstract:
Surface force measurements previously conducted with thiolated gold surfaces showed a decrease in excess film entropy (£GSf), suggesting that hydrophobic force originates from changes in the structure of the medium (water) confined between hydrophobic surfaces. As a follow-up to the previous study, surface force measurements have been conducted using an atomic force microscope (AFM) with hydrophobic silica surfaces at temperatures in the range of 10 to 40¢XC. The silica sphere and silica plate were treated by both chemisorption of octadecyltrichlorosilane (OTS) and physical adsorption of octadecyltrimethylammonium chloride (C18TACl). A thermodynamic analysis of the results show similar results for both of the samples, that both ""Sf and excess film enthalpy ("Hf) become more negative with decreasing thickness of the water layer between the hydrophobic surfaces and decreasing temperature. |"Hf | > |T"Sf| represents a necessary condition for the excess free energy change ("Gf ) to be negative and the hydrophobic interaction to be attractive. Thus, the results obtained with both the silylated and C18TACl-adosrbed silica surfaces in the present work and the thiolated gold suefaces reported before show hydrophobic forces originate from structural changes in the medium. Thermodynamic analysis of SFA force measurements obtained at various temperatures revealed that "Sf were much more negative in the shorter hydrophobic force ranges than in the longer ranges, indicating a more significant degree of structuring in the water film when the two hydrophobic surfaces are closer together. It is believed that the water molecules in the thin liquid films (TLFs) of water form clusters as a means to reduce their free energy when they cannot form H-bonds to neighboring hydrophobic surfaces. Dissolved gas molecules should enhance the stability of structured cluster due to the van der Waals force between the entrapped gas molecules and the surrounding water molecules1, which may enhance the strength of the hydrophobic force. Weaker long-range attractive forces detected in degassed water than in air-equilibrated water was found in the present work by means of AFM force measurements, supporting the effect of dissolved gas on the structuring of water. At last, temperature effects on hydrophobic interactions measured in ethanol and the thermodynamic analysis revealed similar results as those found in water, indicating that the hydrophobic force originates from H-bond propagated structuring in the mediums. •
Ph. D.
25
Schmidt, Marc J. J. "Pulsed laser ablation, deposition and processing of titanium doped Al₂O₃ and its analysis." Thesis, University of Hull, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272491.
Full text
26
Fredriksson, Per. "A strain gradient plasticity analysis of size effects in thin films /." Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-380.
Full text
27
Samadi, Azadeh. "Synthesis and analysis of nano-thin polymer films for separation applications." Connect to this title online, 2009. http://etd.lib.clemson.edu/documents/1247508734/.
Full text
28
Krishna, Arvind. "Viscoelastic stress analysis of thin polyimide films in electronic packaging applications /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487864485228336.
Full text
29
Liyanage, Chinthaka. "Specific property analysis of thin-film semiconductors for effective optical logical operations." Connect to full text in OhioLINK ETD Center, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1217089206.
Full text
30
Ibrahim, Kamarulazizi. "Analysis of amorphous thin-film tandem solar cells and their component layers." Thesis, Heriot-Watt University, 1989. http://hdl.handle.net/10399/923.
Full text
31
Frost, Robert Lewis. "Slow positron annihilation spectroscopy applied to the analysis of the semiconductor, silicide, and titanium nitride structures." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/17298.
Full text
32
Carballo, Jose M. "Residual Stress Analysis in 3C-SiC Thin Films by Substrate Curvature Method." Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1590.
Full textAbstract:
Development of thin films has allowed for important improvements in optical, electronic and electromechanical devices within micrometer length scales. In order to grow thin films, there exist a wide variety of deposition techniques, as each technique offers a unique set of advantages. The main challenge of thin film deposition is to reach smallest possible dimensions, while achieving mechanical stability during operating conditions (including extreme temperatures and external forces, complex film structures and device configurations). Silicon carbide (SiC) is attractive for its resistance to harsh environments, and the potential it offers to improve performance in several microelectronic, micro-electromechanical, and optoelectronic applications. The challenge is to overcome presence of high defect densities within structure of SiC while it is grown as a crystalline thin film. For this reason is important to monitor levels of residual stress, inherited from such grown defects, and which can risk the mechanical stability of SiC- made thin film devices.
Stoney's equation is the theoretical foundation of the curvature method for measuring thin film residual stress. It connects residual film stress with substrate curvature through thin plates bending mechanics. Important assumptions and vii simplifications are made about the film-substrate system material properties, dimensions and loading conditions; however, accuracy is reduced upon applying such simplifications. In recent studies of cubic SiC growth, certain Stoney's equation assumptions are violated in order to obtain approximate values of residual stress average. Furthermore, several studies have proposed to expand the scope of Stoney's equation utility; however, such expansions demand of more extensive substrate deflection measurements to be made, before and after film deposition.
The goal of this work is to improve the analysis of substrate deflection data, obtained by mechanical profilometry, which is a simple and inexpensive technique. Scatter in deflection data complicates the use of simple processes such as direct differentiation or polynomial fitting. One proposed method is total variation regularization of differentiation process; and results are promising for the adaptation of mechanical profilometry for complete measurement of all components of non-uniform substrate curvature.
33
Shinall, Brian Darnell. "Using surface plasmon resonance spectroscopy to characterize thin composite films." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/10157.
Full text
34
York, Timothy Howard. "Pulsed laser deposition of electronic ceramics and analysis of the ablation plume." Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362729.
Full text
35
Lee, Paul Anthony 1961. "Photoelectrochemical and solid state characterization of the spectroscopic and electronic properties of titanyl phthalocyanine." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276853.
Full textAbstract:
Various metal phthalocyanines have been used as dyes, catalysts, indicators, electrophotographic receptors and more recently as active elements in chemical sensors and photoconductive materials for solar energy conversion applications. Of the MPc's, VOPc, GaPc-Cl and TiOPc have shown promise for solar energy conversion devices. GaPc-Cl has also shown promise as a chemical sensor. Up to this point in time, the focus of Pc research in this group has been in the direction of characterizing the photoelectrochemical properties of these materials. Recently, solid state studies of TiOPc have been done to determine the electronic properties of a tetravalent metal Pc, such as conductivity and photoconductivity. Such solid state measurements are facilitated by the use of interdigitated microelectrode arrays which are coated with thin films of various Pc's.
36
Bassi, Andrea Li. "X-ray and light scattering from nanostructured thin films." Thesis, Durham University, 2000. http://etheses.dur.ac.uk/4631/.
Full textAbstract:
The object of this thesis is the study of nanostructured thin films using inelastic fight scattering and elastic x-ray scattering techniques. Their use in combination with other techniques is a powerful tool for the investigation of nanostructured materials. X-ray, Raman and Brillouin characterisation of cluster-assembled carbon films, promising for applications in the field of catalysis, hydrogen storage and field emission, is here presented. X-ray reflectivity (XRR) provided a measure of the density. Raman spectroscopy showed that the local bonding in these amorphous films depends on the size distribution of the clusters and that it is possible to select the cluster size in order to grow films with tailored properties. Brillouin scattering provided a characterisation at the mesoscopic scale and an estimate of the elastic constants, revealing a very soft material. XRR was employed to study density, layering and roughness of a wide range of amorphous carbon films grown with different techniques. Some films possess an internal layering due to plasma instabilities in the deposition apparatus. By comparing XRR with Electron Energy Loss Spectroscopy, a unique value for the electron "effective mass" was deduced and a general relationship between sp(^3)-content and density was found. XRR and H effusion were used to determine the hydrogen content. A study of the size-dependent melting temperature in tin nanoparticle thin films was undertaken with a combined use of X-Ray Diffraction (XRD) and light scattering. A redshift in the position of a Rayleigh peak in the temperature-dependent Brillouin measurements was shown to be related to the melting of the nanoparticles and explained by an effective medium model. XRD also provided information on the low-level of stress in the particles. Low-frequency Raman scattering was used to study the behaviour of the acoustic modes of a single particle as a function of temperature.
37
Thota, Phanikrishna. "PATTERN EVALUATION FOR IN-PLANE DISPLACEMENT MEASUREMENT OF THIN FILMS." UKnowledge, 2003. http://uknowledge.uky.edu/gradschool_theses/307.
Full textAbstract:
The term Gossamer is used to describe ultra-lightweight spacecraft structures that solve the aerospace challenge of obtaining maximum performance while reducing the launch costs of the spacecraft. Gossamer structures are extremely compliant, which complicates control design and ground testing in full scale. One approach is to design and construct smaller test articles and verify their computational models experimentally, so that similar computational models can be used to predict the dynamic performance of full-scale structures. Though measurement of both in-plane and out-of-plane displacements is required to characterize the dynamic response of the surface of these structures, this thesis lays the groundwork for dynamic measurement of the in-plane component. The measurement of thin films must be performed using non-contacting sensors because any contacting sensor would change the dynamics of the structure. Moreover, the thin films dealt with in this work are coated with either gold or aluminum for special applications making the film optically smooth and therefore requiring a surface pattern. A Krypton Fluoride excimer laser system was selected to fabricate patterns on thin-film mirror test articles. Parameters required for pattern fabrication were investigated. Effects of the pattern on the thin-film dynamics were studied using finite element analysis. Photogrammetry was used to study the static in-plane displacement of the thin-film mirror. This was performed to determine the feasibility of the photogrammetric approach for future dynamic tests. It was concluded that photogrammetry could be used efficiently to quantify dynamic in-plane displacement with high-resolution cameras and sub-pixel target marking.
38
Guerrero, Maribel Hernandaz Chemical Sciences & Engineering Faculty of Engineering UNSW. "Honeycomb tructured porous films from different polymer architectures - preparation, mechanism, analysis and post-treatment." Publisher:University of New South Wales. Chemical Sciences & Engineering, 2008. http://handle.unsw.edu.au/1959.4/43341.
Full textAbstract:
This dissertation studies and examines the process of formation of honeycomb structured porous films using various polymer architectures ranging from linear, comb, star polymers and a random copolymer. Four casting methods were designed and applied for the production of structured porous materials. The airflow casting technique, cold-stage casting technique, casting on water technique and emulsion casting technique all based in either direct water introduction to the system or indirect condensation from the environment showed to be viable options for casting of high quality porous materials. The control and study of the effect of environmental conditions towards the quality of the films has been examined through the design of a casting device and the use of the casting methods. Furthermore, the versatility of each of the architectures towards the production of honeycomb porous films has been studied. Highly regular honeycomb structured porous films were obtained from all the complex architectures namely comb polymers, star polymers and the random copolymer. However, the linear polymers did not result in regular films. Moreover the quality of the films has been assessed and mathematically quantified. In addition, some mechanistic aspects of the process of formation of honeycomb structured porous films have been addressed. Variables such as the viscosity and evaporation of polymer solutions were examined. Furthermore, the precipitation behaviour of various polymer architectures was inspected. Only the polymer architectures showing a lower viscosity and late precipitation deemed highly regular films. Finally, the modification of highly regular films from a comb polymer and a random copolymer was successfully performed for the first time by grafting a thermoresponsive polymer from the RAFT groups already present in the porous material. The non-treated films showed a typical hydrophobic behaviour for a porous membrane however after the grafting, the films exhibited hydrophilic behaviour.
39
Gulses, Alkan Ali. "Ellipsometric And Uv-vis Transmittance Analysis Of Amorphous Silicon Carbide Thin Films." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605589/index.pdf.
Full textAbstract:
The fundamentals of the ellipsometry are reviewed in order to point out the strengths and weaknesses of the ellipsometric measurements. The effects of the surface conditions (such as degree of cleanliness, contaminated thin layer, roughness etc&hellip) on the ellipsometric variables are experimentally studied
the optimum procedures have been determined. Hydrogenated amorphous silicon carbide (a-Si1-xCx:H) thin films are produced by plasma enhanced chemical vapor deposition (PECVD) technique with a circular reactor, in a way that RF power and carbon contents are taken as variables. These samples are analyzed using multiple angle of incidence ellipsometer and uv-vis spectrometer. These measurements have inhomogeneities in optical constants, such as thicknesses, refractive indices and optical energy gaps along the radial direction of the reactor electrode for different power and carbon contents.
40
Klasen, Alexander [Verfasser]. "Synthesis and Analysis of Thin Films for Perovskite Solar Cells / Alexander Klasen." Mainz : Universitätsbibliothek der Johannes Gutenberg-Universität Mainz, 2020. http://d-nb.info/1224895940/34.
Full text
41
Dizayee, Wala. "Measurement and analysis of magnetic and magneto optical properties of thin films." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/18193/.
Full text
42
Frantzeskakis, Emmanouil. "Analysis of potential applications for the templated dewetting of metal thin films." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33625.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2005.Includes bibliographical references.
Thin films have a high surface-to-volume ratio and are therefore usually morphologically unstable. They tend to reduce their surface energy through transport of mass by diffusion. As a result, they decay into a collection of small isolated islands or particles. This solid-state process, known as thin film dewetting, can be initiated by grooving at grain boundaries or triple junctions. Dewetting of thin films on topographically modified substrates has many interesting characteristics. It is a novel self-assembly process for the formation of well-ordered nanoparticle arrays with narrow size distributions and uniform crystallographic orientation. Potential applications of particles resulting from templated thin film solid-state dewetting are reviewed. Applications in patterned magnetic information-storage media, plasmon waveguides, and catalytic growth of ordered arrays of semiconducting nanowires and carbon nanotubes are discussed. Templated dewetting technology has not been fully developed, and technological barriers are identified for all of the commercial applications considered.
(cont.) However, the self-assembly characteristics of templated dewetting may ultimately offer advantages in the manufacture of both patterned media and catalytic nanomaterial growth technologies.
by Emmanouil Frantzeskakis.
M.Eng.
43
Shute, Hazel Anne. "Mathematical analysis of novel magnetic recording heads." Thesis, University of Plymouth, 1995. http://hdl.handle.net/10026.1/2392.
Full textAbstract:
As a contribution to increasing the areal density of digital data stored on a magnetic recording medium, this thesis provides mathematical analyses of various magnetic recording heads. Each of the heads considered here is for use in a perpendicular recording system, writing to or reading from a multi-layer medium which includes a high magnetic permeability layer between the data storage layer and the substrate. The exact two-dimensional analysis is performed in each case by one of two methods: either Fourier analysis or conformal mapping. The types of heads analysed include conventional styles but particular emphasis is placed on the effects of the novel idea of potential grading across the pole pieces. Exact head fields are derived for thin film heads with both constant and linearly varying pole potentials, single pole heads with linearly and arbitrarily varying pole potentials and shielded magnetoresistive heads, all in the presence of a magnetic underlayer. These and other published solutions are used to derive output characteristics for perpendicular replay heads, which are compared with published theoretical and experimental results where possible. The Fourier solutions obtained are in the form of infinite series dependent on at least one set of coefficients which are determined by infinite systems of linear equations. Approximations to the potentials in the head face planes, independent of these coefficients, are derived from the exact Fourier solutions. The accuracy of these approximations is demonstrated when they are used to estimate the vertical field components and the spectral response functions. Heads with graded pole potentials are found to have more localised vertical field components than the corresponding constant potential heads. They are also better suited for use with thin media for 'in contact' recording.
44
Běhounek, Tomáš. "Imaging Reflectometry Measuring Thin Films Optical Properties." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-233857.
Full textAbstract:
V této práci je prezentována inovativní metoda zvaná \textit{Zobrazovací Reflektometrie}, která je založena na principu spektroskopické reflektometrie a je určena pro vyhodnocování optických vlastností tenkých vrstev .\ Spektrum odrazivosti je získáno z map intenzit zaznamenaných CCD kamerou. Každý záznam odpovídá předem nastavené vlnové délce a spektrum odrazivosti může být určeno ve zvoleném bodu nebo ve vybrané oblasti.\ Teoretický model odrazivosti se fituje na naměřená data pomocí Levenberg~-~Marquardtova algoritmu, jehož výsledky jsou optické vlastnosti vrstvy, jejich přesnost, a určení spolehlivosti dosažených výsledků pomocí analýzy citlivosti změn počátečních nastavení optimalizačního algoritmu.
45
Lee, Bong Jae. "Fabrication and Analysis of Multilayer Structures for Coherent Thermal Emission." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19839.
Full textAbstract:
This dissertation describes a theoretical and experimental study on coherent thermal emission from thin-film multilayer structures. A novel multilayer structure consisting of a one-dimensional photonic crystal and a polar material (or a metal) is proposed as a coherent thermal-emission source. Surface electromagnetic waves can be excited at the edge of photonic crystal, enabling coherent emission characteristics (i.e., spectral- and directional-selectivity in the emissivity). A near-infrared coherent emission source is designed and fabricated using vacuum deposition and chemical vapor deposition techniques. Measurements were performed using a Fourier-transform infrared spectrometer and a laser scatterometer. The agreement between the resonance conditions obtained from experiments and the calculated dispersion relation confirms that surface waves at the photonic crystal-metal interface can be utilized to build coherent thermal-emission sources. The second part of this dissertation focuses on the energy propagation direction in near-field thermal radiation. The energy streamline method based on the Poynting vector is applied to near-field thermal radiation by incorporating the fluctuational electrodynamics, in which thermal emission is viewed as originated from random motion of electric dipoles at temperatures above absolute zero. It is shown that the Poynting vector is decoupled for each parallel wavevector component due to the randomness of thermal emission. The spectral radiative energy travels in infinite directions along curved lines; this is a fundamental characteristic of near-field thermal radiation. The findings in this dissertation are important for the design of near-field optical sensors and energy conversion devices.
46
Jenniches, Hartmut. "Magnetic and magneto-optic properties of thin films of the Heusler alloy PtMnSb." Thesis, Coventry University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335325.
Full text
47
Booman, Richard Albert 1957. "DETERMINATION OF LOSS MECHANISMS IN LONG RANGE SURFACE PLASMON MODES." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/275490.
Full text
48
Kumar, Nishith. "Design and construction of a novel thermal interferometer." Swinburne Research Bank, 2009. http://hdl.handle.net/1959.3/64905.
Full text
49
Chou, S. H., and 周信宏. "Stress Analysis of Thin Films." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/33194015880527656154.
Full text
50
Tseng, Ching-Chieh, and 曾敬傑. "Residual Stress Analysis for Thin Films." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/60128756159952360285.
Full textAbstract:
碩士國立臺灣海洋大學
機械與機電工程學系
99
The thermal-induced residual stress in the polycrystalline thin films is investigated in this thesis. In addition to considering the difference in thermal expansion between thin film and substrate, the effect of the orientation of grains on the residual stress is also investigated in the current study. The variations in the stiffnesses and the coefficients of thermal expansion among the neighboring grains with different orientations further complicate the residual stress distribution. The analysis is based on the grain continuum model in which grain structures are treated as the collections of individual continua with different mechanical properties. To simply the analysis, only films with grains having two different orientations are considered. Both grains are assumed to have the same size and shape and regularly distribute. The finite element package ANSYS is used to perform the thermo-elastic analysis. Numerical results of three types of thin films, namely Cu, TiN and BN are reported.