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1
Poulter, Neil. "Novel antimicrobial plasma deposited films." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518294.
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Bacterial infection is a growing concern in hospital and community settings, where the issue of biofilms is a major problem. Most current methods of preventing microbial attachment and biofilm formation are limited due to application, process or inherent flaws. It was proposed that thin films containing an organometallic element could be deposited using plasma, a quick, clean surface modification technique; to create antimicrobial films which could then be applied to a range of substrates. Several novel antimicrobial monomer systems were synthesised and characterised based on silver, copper and zinc as the active constituent with phosphines, phosphites, maleimide and a novel Schiff base among the ligand systems. All monomers were found to greatly inhibit the growth of P. aeruginosa and S. aureus in solution and on solid media. Successful monomers were deposited onto suitable substrates (glass, gold, plastics, non-woven polypropylene) using continuous wave and pulse plasma, with the films characterised and low levels of active metal found in analysis using XPS and SIMS. Films were tested against solutions of pathogenic bacteria using a number of traditional and modern microbiological techniques and found to inhibit growth under a range of conditions, potentially due to the synergistic action of metal and ligand on bacterial cells. Effective control of bacteria was exhibited at times varying from 1h to 24h+. Highly volatile compounds were produced which allowed quick deposition of plasma films, which showed excellent activity against bacteria (99.9%+ growth reduction), indicating viability for potential application. All films tested showed no inhibition or toxicity to eukaryotic cells.
2
Skillen, Norman William. "Thin films of zirconia deposited by MOCVD." Thesis, University of Salford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258342.
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Seok, Jin Woo. "SPUTTER DEPOSITED CR/CRN NANOCRYSTALLINE THIN FILMS." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin985901057.
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Anutgan, Mustafa. "Investigation Of Plasma Deposited Boron Nitride Thin Films." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608611/index.pdf.
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Hexagonal boron nitride (h-BN) thin films are deposited by plasma enhanced
chemical vapor deposition (PECVD). Effects of heat treatment and source gases on
the structure and physical properties are investigated. Chemical bonding is analyzed
in comparison with the better understood isoelectronic carbon compound, graphite. It
seems that the basic difference between h-BN and graphite arises from the different
electronegativities of boron and nitrogen atoms. Optical absorptions in UV-visible
range for crystalline and amorphous structures are outlined. The expressions used for
the evaluation of mechanical stress induced in thin films are derived. The deposited
films are considered to be turbostratic as they do not exhibit the characteristic optical
absorption spectra of a crystal. A new system, stylus profilometer, is implemented
and installed for thin film thickness and mechanical stress measurements. Hydrogen
atom density within the films, estimated from FTIR spectroscopy, is found to be a
major factor affecting the order and mechanical stress of the films. Heat treatment of
the films reduces the hydrogen content, does not affect the optical gap and slightly
increases the Urbach energy probably due to an increased disorder. Increasing the
nitrogen gas flow rate in the source gas results in more ordered films. The virtual
crystal of these films is detected to be unique. Relative bond concentrations of the constituent elements indicate a ternary boron-oxygen-nitrogen structure. The
physical properties of h-BN such as high resistivity and wide band gap seem suitable
for optoelectronic applications such as gate dielectrics in thin film transistors and
light emitting devices in the blue region.
5
Kandasamy, Ispran S. "Metalorganic chemical vapour deposited titanium dioxide thin films." Thesis, Brunel University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235909.
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Petruczok, Christy D. (Christy Danielle). "Enabling integration of vapor-deposited polymer thin films." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/89947.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references.
Initiated Chemical Vapor Deposition (iCVD) is a versatile, one-step process for synthesizing conformal and functional polymer thin films on a variety of substrates. This thesis emphasizes the development of tools to further enable the use of iCVD for industrial applications. The ability to pattern polymer thin films is a prerequisite for device fabrication. Two methods were developed for patterning iCVD polymers. The first technique facilitated patterning of nano- and microscale features of any iCVD thin film on planar surfaces. Retention of polymer functionality was demonstrated by incorporating the features into high-resolution resistive sensors. The second method adapted photolithographic techniques to achieve patterning on highly curved surfaces. Non-planar substrates were coated with a uniform layer of a functionalized, photoreactive iCVD polymer and exposed to ultraviolet light through a flexible mask. Exposed regions became insoluble in a developing solvent. The resolution and sensitivity of this iCVD-based negative photoresist were comparable to those of commercial products. Additionally, the patterned polymer was used as a mask for patterning metal on planar and curved surfaces. iCVD is typically a semi-continuous process. A batch process was investigated in order to minimize the use of expensive and corrosive reactants. The chemical functionality and conformality of the films were unaffected by the change in processing mode. Reaction yield was improved by one to two orders of magnitude for several film chemistries. iCVD is also unique in that it enables the deposition of cross-linked polymer films, which are difficult to create using conventional, solution-based methods. To potentially enhance durability, cross-linked poly(divinylbenzene) and poly(4-vinylpyridine-co-divinylbenzene) films were synthesized via iCVD. This is the first vapor-phase synthesis of the copolymer, which is a major component of many commercial ion exchange membranes. The degree of cross-linking was quantified using spectroscopic methods and was tightly controlled by adjusting the flow rate of divinylbenzene. Corresponding changes in the elastic moduli of the films were confirmed using nanoindentation. The first vapor-phase synthesis of poly(vinyl cinnamate) was also demonstrated. The cross-linking density of this polymer increases upon exposure to ultraviolet light and is readily quantifiable. Vinyl cinnamate was incorporated into a copolymer with N-isopropylacrylamide, yielding a temperature and light-responsive thin film.
by Christy D. Petruczok.
Ph. D.
7
Peterson, Sarah M. "Influence of scale, geometry, and microstructure on the electrical properties of chemically deposited thin silver films /." Connect to title online (ProQuest), 2007. http://proquest.umi.com/pqdweb?did=1453183211&sid=2&Fmt=2&clientId=11238&RQT=309&VName=PQD.
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Thesis (Ph. D.)--University of Oregon, 2007.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 95-101). Also available online in ProQuest, free to University of Oregon users.
8
Hajjar, Jean-Jacques Joseph. "Characterization of chemical vapor deposited polycrystalline silicon thin films." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15006.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING
Bibliography: leaves 134-139.
by Jean-Jacques Joseph Hajjar.
M.S.
9
Cole, Matthew Thomas. "Dry-transfer of chemical vapour deposited nanocarbon thin films." Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/241515.
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This thesis presents the development of chemical vapour deposited (CVD) graphene and multi-walled carbon nanotubes (MWCNTs) as enabling technologies for flexible transparent conductors offering enhanced functionality. The technologies developed could be employed as thin film field emission sources, optical sensors and substrate-free wideband optical polarisers. Detailed studies were performed on CVD Fe and Ni catalysed carbon nanotubes and nanofibres on indium tin oxide, aluminium and alumina diffusion barriers. Activations energies of 0.5 and 1.5 eV were extracted supporting surface diffusion limited catalysis forCNTs and CNFs. For the first time an activation energy of 2.4 eV has been determined for Cu-catalysed growth of CVD graphene. Graphene was shown to deviate significantly from the more traditional rate-limited surface diffusion and suggests carbon-atom-lattice integration limited catalysis. An aligned dry-transferred MWCNT thin film fabrication technique was developed using MWCNTs of varied lengths to control the optical transparency and conductivity. A process based on the hot-press lamination of bilayer CVD graphene (HPLG) was also developed. Transport studies revealed that these thin films behave, in a macroscopic sense, similar to traditional c-axis conductive graphite and deviate toward tunnel dominated conduction with increasing degrees of network disorder. Various MWCNT-based thin film field emitters were considered. Solution processing was shown to augment the surface work function of the MWCNTs resulting in reduced turn-on electric fields. Integrated zinc oxide nanowires were investigated and were shown to ballast the emission, thereby preventing tip burn out, and offered lower than expected turn-on fields due to the excitation of a hot electron population. To obviate nearest neighbour electrostatic shielding effects an electrochemical catalyst activation procedure was developed to directly deposit highly aligned sparse carbon nanofibres on stainless steel mesh. Highly-aligned free-standing MWCNT membranes were fabricated through a solid-state peeling technique. Membranes were spanned across large distances thereby offering an ideal platform to investigate the unambiguous photoresponse of MWCNTs by removing all extraneous substrate interfaces, charge traps and nanotube-electrode Shottky barriers as well as using pure, chemically untreated material. Oxygen physisorbtion was repeatedly implicated through in-situ lasing and in-situ heated EDX measurements, FT-IR and low temperature transport and transfer measurements. A MWCNT membrane absorptive polariser was fabricated. Polarisers showed wideband operation from 400 nm to 1.1 μm and offered operation over greater spectral windows than commercially available polymer and glass-support dichroic films. Ab-initio simulations showed excellent agreement with the measured polarisation attributing the effect to long-axis selective absorption.
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Fraser, Samuel Carroll. "Prediction of thin films obliquely deposited in rotating recessed cones." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/9340.
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Borer, Aidan. "Internal stress and adhesion in laser photoanalytically deposited tungsten films." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258167.
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Trevor, Colin. "Transmission electron microscopy of chemical vapour deposited diamond films." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295064.
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Proffitt, Simon. "Surface chemical studies of chemical vapour deposited diamond thin films." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393996.
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Liu, Andong. "Mechanically flexible vapor-deposited polymeric thin films for electrochemical devices." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/117992.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references.
The concept of self-powered wearable electronic system has been emerging. Such a system consists of three units: an intelligent end-user electronic device for exporting functions, an energy generation/conversion device responsible for harvesting/scavenging renewable energy, and additionally an energy storage device to ensure non-intermittent operation. The three units should be matched up in terms of energy and power, which demands substantial efforts in research for advancing all the components - the power consumptions of the electronics need to be reduced, the efficiencies of the energy scavenging devices ought to be improved, and the capacities of the energy storage devices are desired to be enhanced. An additional requirement is that the three units should all be made "human-friendly", namely lightweight, flexible and wearable. This necessitates the fabrication of all to be compatible with the unconventional substrates, such as papers and plastics. Along the way to these goals, tremendous opportunities and challenges with regards to materials and device designs are present. This thesis focuses on the development of mechanically flexible thin-film materials for electrochemical devices, towards the achievement of self-powered wearable electronic systems. Initiated chemical vapor deposition (iCVD) and oxidative chemical vapor deposition (oCVD), which are non-destructive to fragile substrates, have been employed for the synthesis of the polymeric thin films. As an effort to enhance the functional end-users, pinhole-free ionic liquid gels with thickness down to 20 nm have been prepared for the first time via iCVD. They show great promise as soft gate insulators for low-power high-speed thin film transistors, which are central to a variety of wearable electronics. To improve the energy storage unit, supercapacitors, a promising energy storage device for low-power devices, have been vapor-printed via oCVD onto flexible low-cost substrates, papers and nylon membranes. Additionally, an ultrathin gel electrolyte coating has been developed to boost the performance stability of polymeric capacitive materials.
by Andong Liu.
Ph. D.
15
Lorenzzi, Jean Carlos da Conceição. "Boron nitride thin films deposited by magnetron sputtering on Si3N4." Master's thesis, Universidade de Aveiro, 2007. http://hdl.handle.net/10773/2307.
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Mestrado em Ciência e Engenharia de MateriaisO Nitreto de boro é um material polimorfo, sendo as fases hexagonal (h-BN) ecúbicas (c-BN) as predominantes. A fase hexagonal do nitreto de boro apresenta uma estrutura em camadas sp2, semelhante a grafite, enquanto que a fase cúbica do nitreto de boro tem forte ligações sp3, como o diamante. O h- BN apresenta boas propriedades dieléctricas, é um material refractário, resistente a corrosão, é conhecido por ser um lubrificante sólido que tem aplicações na protecção de moldes de injecção e em outros processos mecânicos de elevadas temperaturas ou lubrificação em ambientes de elevada humidade. Contudo, o h-BN é extremamente macio. Em contraste, o c-BN apresenta excelentes propriedades térmicas, eléctricas e ópticas, sendo ainda um dos materiais conhecidos com dureza mais elevada (70 GPa). Além disso, c-BN apresenta propriedades superiores em relação ao diamante quando aplicado em ferramentas de corte na maquinagem de materiais ferrosos, devido a sua alta estabilidade química a altas temperaturas durante a maquinagem. Essa combinação de propriedades faz dele um forte candidato no campo das ferramentas de corte e em dipositivos electrónicos. No presente trabalho, filmes finos de nitreto de boro foram depositados por DC e RF magnetron sputtering, utilizando alvos de B4C e h-BN prensados a quente, numa atmosfera de deposição contituída por misturas de Ar e N2. Os filmes finos de BN foram depositados simultâneamente em dois tipos de substratos: cerâmicos de Si3N4 com diferentes acabamentos superficiais e em discos de Si(100). A influência dos parâmetros de deposição, tais como a temperatura do substrato, composição da atmosfera de deposição na espessura dos filmes, taxa de deposição, cristalinidade, tensão residual, fases presentes e dureza, foram sistematicamente investigados usando técnicas como, SEM, XRD, FT-IR e nanodureza. O h-BN foi a principal fase observada nas análises dos espectros de FT-IR e nos difractogramas de XRD. O estado de tensão dos filmes finos de BN films é estremamente afectado pela temperatura do substrato, composição do gás de trabalho e pelo acabamento superficial dos substratos. O estudo da influência da temperatura mostraram que a taxa de deposição aumenta com o aumento da temperatura do substrato. Tensões residuais elevadas ocorrem para altas concentrações de árgon e para substratos polidos em suspensão de diamante 15 μm. Nos espectros de FT-IR, a forma das bandas de vibração variam de uma forma alargada para uma configuração estreita, correspondendo a uma menor desordem da fase hexagonal do BN, devido a variação da composição da atmosfera de deposição. Os valores de dureza obtidos estão numa faixa que vai desde os valores do h-BN macio (6 GPa) até valores próximos dos limites encontrados para filmes contendo a fase cúbica (16 GPa ), acima de 40%. ABSTRACT: Boron nitride is a polymorphic material, the hexagonal (h-BN) and the cubic (c- BN) being its main crystalline structure. The hexagonal boron nitride has a layered sp2-bonded structure, similar to graphite, while the cubic boron nitride has a hard sp3-bonded diamond-like structure. h-BN presents good dielectric properties, refractoriness, corrosion-resistant characteristics, low friction and low wear rate, and it is a well-known solid lubricant which has wide applications in metal-forming dies and other metal working processes at high temperatures or lubrication in high relative humidity environments. However, h-BN is mechanically soft. In contrast, c-BN presents excellent thermal, electrical and optical properties, with a hardness up to 70 GPa. Moreover, c-BN is superior to diamond as cutting tool for ferrous materials due to its high thermal chemical stability during machining. In the present work, thin films of boron nitride have been deposited by D.C. and R.F. magnetron sputtering from hot-pressed B4C and h-BN targets, using mixtures of Ar and N2, as working gases. The BN thin films were deposited simultaneously on two different substrates: Si3N4 ceramics with different surface finishing and Si(100) wafers. The influence of parameters such as substrate temperature and working gas composition ratio, on film thickness, deposition rate, cristallinity, residual stress, phase composition and hardness, were systematically investigated using techniques like SEM, XRD, FT-IR and nanohardness. h-BN was the main observed phase. The stress-state of the thin BN films is largely affected by the substrate temperature, working gas composition and the substrate surface finishing. The substrate temperature studies show that the deposition rate increases with an increasing of the substrate temperature. Large high residual stresses are developed for higher argon ratios and for substrate finishing with 15 μm diamond paste. In the FT-IR spectra, the shape of the vibration band changes from broad to narrow, corresponding to a less disorder h-BN phase, due to the working gas composition. The hardness values obtained are typical in the range of a soft h-BN (6 GPa) to values approaching the limit of the range reported for films containing a fraction of cubic phase (16 GPa ) up to 40%.
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Schäfer, Christian Martin. "Towards organic-inirganic hybrid thin films deposited by ALD/MLD." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22267.
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Mestrado em QuímicaA técnica de deposição por camada atómica (ALD) permite a deposição de filmes finos em fase de vapor de alta qualidade com um controlo de espessura à nano-escala. No presente trabalho foi demonstrado a deposição de filmes finos de óxido de zinco (ZnO) por ALD de elevada uniformidade em diferentes substratos, incluído nano-estruturas como por exemplo, nanotubos de carbono. Demonstrou-se por difracção de raio-X que o processo de deposição do ZnO originou a formação da estrutura da hexagonal, na fase wurtzite, com uma taxa de crescimento por ciclo de 1.9 Å. A deposição de filmes finos de natureza inorgânica (e.g. óxidos metálicos) por ALD está bem estabelecida contrariamente à emergente deposição por camada molecular (MLD) de filmes finos puramente orgânicos. Actualmente, a combinação de ALD/MLD começa a ganhar importância na criação de estruturas híbridas do tipo orgânica-inorgânicas. Nomeadamente, através da selecção adequada dos precursores, é possível obter diferentes arquitecturas funcionais em forma de filme fino, incluindo nano-laminados, superestruturas e redes metalo-orgânicas (MOFs) nano-porosas. A deposição de MOFs por ALD/MLD surge como uma alternativa para superar as desvantagens dos métodos convencionais de deposição de filmes finos baseados em soluções. Este trabalho contempla também a revisão da literatura no que diz respeito à síntese de este tipo de filmes finos obtidos em fase de vapor. Procedeu-se à reprodução dos resultados da literatura tendo como objectivo a síntese de filmes finos híbridos orgânico-inorgânicos (e.g. MOFs). Numa primeira fase efectuou-se a transformação vapor-sólido de um filme de ZnO crescido por ALD por exposição ao vapor de 2-metilimidazol. Posteriormente usou-se um processo ALD/MLD com o propósito de depositar uma estrutura do tipo zeólito (ZIF-8) a partir da reacção do dietilzinco (DEZ) e o 2-metilimidazol. Finalmente realizou-se a síntese de dois sistemas de filmes finos híbridos com base no ácido tereftálico como precursor orgânico e os seguintes precursores organometálicos: DEZ e Eu(TMHD)3. Para o caso do sistema DEZ/TPA, a formação da ligação Zn-TP nos filmes híbridos, foi observada por espectroscopia de FTIR
Atomic layer deposition is a state-of-the-art vapor phase deposition method for the creation of high quality thin films with nanoscale thickness control. As demonstrated in this work by the deposition of ZnO with a home-built reactor, ALD enables uniform and conformal film deposition even on complex nanostructures like carbon nanotubes. Deposition of hexagonal wurtzite ZnO proven by GIXRD with a growth-per-cycle of 1.9 Å, determined from XRR thickness measurements, was demonstrated. While the ALD synthesis of inorganic thin films, such as metal oxides is widely established, the organic counterpart molecular layer deposition (MLD) is still emerging. Recently, combining ALD/MLD has attracted great interest for the creation of organic-inorganic hybrid structures. By choice and adaptation of suitable precursors a great versatility of functional thin film architectures is achievable, spanning from novel multilayer nanolaminates and superstructures for thermoelectrics, over luminescent lanthanide hybrid films for optical application to even crystalline, nanoporous metal-organic frameworks (MOFs) as low-κ dielectrics in microdevices. Especially in the field of MOFs, a clean and precise synthesis route by ALD/MLD is desirable for device implementation in order to overcome the drawbacks of conventional, solution-based thin film deposition techniques. In this work, recent advances towards these vapor-processed hybrids are reviewed. Then, the reproduction of literature results leading to the deposition of organic-inorganic hybrid thin films (e.g. MOFs) was studied. The feasibility of a vapor-solid transformation of a sacrificial ALD-grown ZnO film by exposure to 2-methylimidazole (HMIM) and a direct ALD/MLD method using HMIM and diethylzinc (DEZ) towards a zeolitic imidazole framework (ZIF-8) have been attempted. Finally, the synthesis of two different hybrid films was studied involving the organic precursor terephthalic acid (TPA) combined with the organometallic precursors DEZ or Eu(TMHD)3. In case of the DEZ/TPA system, the deposition of a hybrid thin film with Zn-terephthalate bondings was evidenced by FTIR spectroscopy.
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Bragg, Donald. "Photocatalytic Oxidation of Carbon Monoxide Using Sputter Deposited Molybdenum Oxide Thin Films on a Silicon Dioxide Substrate." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/BraggD2007.pdf.
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Peterson, Sarah M. 1975. "Influence of scale, geometry, and microstructure on the electrical properties of chemically deposited thin silver films." Thesis, University of Oregon, 2007. http://hdl.handle.net/1794/8453.
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xv, 101 p. ; ill. (some col.) A print copy of this title is available through the UO Libraries under the call number: KNIGHT QC176.84.E5 P47 2007Silver films with nanoscale to mesoscale thicknesses were produced by chemical reduction onto silica substrates and their physical and electrical properties were investigated and characterized. The method of silver deposition was developed in the context of this research and uses a single step reaction to produce consistent silver films on both flat silica coverslips and silica nanospheres of 250-1000 nm. Both the structure and the electrical properties of the silver films are found to differ significantly from those produced by vacuum deposition. Chemically deposited (CD) silver is not uniformly smooth, but rather is granular and porous with a network-like structure. By quantitatively accounting for the differences in scale, geometry, and microstructure of the CD films, it is found that the same models used to describe the resistivity of vacuum deposited films may be applied to CD films. A critical point in the analysis that allows this relation involves the definition of a geometric parameter, g, which replaces the thickness, t, as the critical length that influences the electrical properties of the film. The temperature dependent properties of electrical transport were also investigated and related to the microstructure of the CD films. A detailed characterization of CD silver as shells on silica spheres is also presented including physical and optical properties. In spite of the rough and porous morphology of the shells, the plasmon resonance of the core-shell structure is determined by the overall spherical shell structure and is tunable through variations in the shell thickness. Preliminary investigations into the electrical transport properties of aggregates of silver coated spheres suggest similarities in the influence scale, geometry, and microstructure to silver films on flat substrates. The aggregates of shells also exhibit pressure related resistance behavior due to the composite structure.
Adviser: Miriam Deutsch
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Reed, Amber Nicole. "Characterization of Inert Gas RF Plasma-Treated Indium Tin Oxide Thin Films Deposited Via Pulsed DC Magnetron Sputtering." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1221763086.
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Millar, Mark A. W. "Plasma deposited silicon incorporated amorphous carbon thin films for automotive applications." Thesis, University of Ulster, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.535144.
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Todi, Ravi. "INVESTIGATIONS ON RF SPUTTER DEPOSITED SICN THIN FILMS FOR MEMS APPLICATIONS." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3330.
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With the rapid increase in miniaturization of mechanical components, the need for a hard, protective coatings is of great importance. In this study we investigate some of the mechanical, chemical and physical properties of the SiCN thin films. Thin films of amorphous silicon carbide nitride (a-SiCxNy) were deposited in a RF magnetron sputtering system using a powder pressed SiC target. Films with various compositions were deposited on to silicon substrate by changing the N2/Ar gas ratios during sputtering. Nano-indentation studies were performed to investigate the mechanical properties such as hardness and reduced modulus of the SiCN films. Surface morphology of the films was characterized by using atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) data indicated that the chemical status is highly sensitive to the nitrogen ratios during sputtering. Further, the films were annealed in dry oxygen ambient in the temperature range of 400 – 900°C and characterized using XPS to investigate the chemical composition and oxidation kinetics at each annealing temperature. The surface roughness of these films was studied as a function of annealing temperature and film composition with the help of a "Veeco" optical profilometer. Nano-indentation studies indicated that the hardness and the reduced modulus of the film are sensitive to the N2/Ar ratio of gas flow during sputtering. AFM studies revealed that the films become smoother as the N2/Ar ratio is increased. XPS data indicated the existence of C-N phases in the as-deposited films. The study of oxidation kinetics of RF sputter deposited SiCN thin films, using XPS, suggest that N2 co-sputtering helps to suppress the formation of a surface oxide, by allowing un-bonded Si to bond with N and C inside the vacuum chamber as opposed to bonding with O in atmosphere.M.S.M.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
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Prakash, Adithya. "Investigation on electrical properties of RF sputtered deposited BCN thin films." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5838.
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The ever increasing advancements in semiconductor technology and continuous scaling of CMOS devices mandate the need for new dielectric materials with low-k values. The interconnect delay can be reduced not only by the resistance of the conductor but also by decreasing the capacitance of dielectric layer. Also cross-talk is a major issue faced by semiconductor industry due to high value of k of the inter-dielectric layer (IDL) in a multilevel wiring scheme in Si ultra large scale integrated circuit (ULSI) devices. In order to reduce the time delay, it is necessary to introduce a wiring metal with low resistivity and a high quality insulating film with a low dielectric constant which leads to a reduction of the wiring capacitance. Boron carbon nitride (BCN) films are prepared by reactive magnetron sputtering from a B4C target and deposited to make metal-insulator-metal (MIM) sandwich structures using aluminum as the top and bottom electrodes. BCN films are deposited at various N2/Ar gas flow ratios, substrate temperatures and process pressures. The electrical characterization of the MIM devices includes capacitance vs. voltage (C-V), current vs voltage, and breakdown voltage characteristics. The above characterizations are performed as a function of deposition parameters.M.S.E.E.
Masters
Electrical Engineering and Computing
Engineering and Computer Science
Electrical Engineering
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Boyd, Adrian. "Composition, structure and properties of sputter deposited calcium phosphate thin films." Thesis, University of Ulster, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311526.
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Okolo, Brando Chidi. "Stress and microstructure of sputter deposited thin copper and niobium films." Stuttgart : Univ., Max-Planck-Institut für Metallforschung, 2003. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10567507.
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Lau, Yu-Hin F. (Yu-Hin Felix). "MEMS structures for stress measurements for thin films deposited using CVD." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/9041.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2001.Includes bibliographical references (p. 76-79).
Mechanical stress in thin films is an important reliability issue in microelectronic devices and systems. The presence of large stresses can lead to the formation of defects that can cause device failure. The ability to control the magnitude of stress during film formation is, therefore, crucial to the fabrication of defect-free and reliable electronic devices and systems. However, the origin of stress in thin films is still a subject of intense debate. The development of a detailed understanding of the origin of stress hinges on our ability to make accurate stress measurements during and after film deposition. To this end, two novel MEMS structures were developed to measure the stress of thin films deposited using chemical vapor deposition (CVD). Buckled SOI membranes were designed and fabricated for the measurement of the stress in thin films deposited on them. A simple analytic model was developed and calibrated to assess the pre-deposition and post-deposition buckling of the structures. By measuring the changes in mechanical responses upon film deposition, it was successfully demonstrated that stress in thin films can be accurately measured. In particular, the stresses in evaporated chromium films measured using the SOI membranes and the curvature method were found to agree to within 5%. Stress pointers were designed and fabricated for in-situ stress measurements of CVD thin films. The design was based on mechanically amplified rotation and the novel concept of "footprinting". Stress is recorded during film formation in the form of beam rotation, which is also dependent on film thickness. As a result, stress can be measured as a function of film thickness in post-deposition analyses, without using real-time measurements during deposition. The fabricated structures were found to bend down and stick to the substrate. PECVD films were found to deposit non-uniformly underneath the beams, thereby complicating the mechanical responses of the stress pointers. A new and improved design is proposed.
by Yu-Hin F. Lau.
S.M.
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Rind, M. Akhtar. "Photovoltaic applications of Si and Ge thin films deposited by PECVD." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/370453/.
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This thesis represents a systematic study of amorphous silicon microcrystalline silicon and germanium thin films, and a-Si:H thin film solar cells fabricated using an OPT plasma lab 100 RF PECVD system carried out with a view to studying novel lighttrapping structures for thin film solar cells and novel IR photovoltaic cells. The work includes the optimisation of amorphous based single layers by optical and electrical characterisation, their doping and the fabrication and optimisation of single junction solar cells. These developments were extended to include deposition of microcrystalline and germanium films with the aim of developing a range of multijunction and single junction research devices. The optical characterisation of intrinsic amorphous based layers shows that device-grade layer fabrications are achievable with more than 90% absorption in the 450 to 550 nm wavelength range which can be deposited at 4-5˚A/s with good thickness uniformity. The bandgap of intrinsic amorphous layers can be tuned from 1.4 to 1.7 eV. Secondary Ion Mass Spectroscopy (SIMS) depth profile characterisation has verified that doping levels in p-type and n type are in the range of 1021 atoms/cm3 which can maintain high open circuit voltage of 0.83V in the single junction device. Systematic single layers well as in-device optimisations lead to the best single junction devices fabricated at a temperature of 250oC and at a pressure of 350 mT and of initially 8.22% efficiency. Initial quantum efficiency (QE) measurements show 75% photon absorption at 550 nm wavelength. A novel technique of wavelength and angle resolved scattering (WARS) measurements have been used to analyse the effects of textured TCOs on light-trapping in single junction device. Showing Asahi-U to be the best substrate with regards to light-trapping, although thicker films benefited more from TEC8 . Deposition of microcrystalline silicon and germanium have also been reported. More focus has been given to optical characterisation of germanium films whose absorption has reached more than 70% in 400 to 1600 nm wavelength range with successful n-type and p-type doping. Ohmic contacts with a low resistivity of 0.029-cm for p-type Ge with the usage of Ni have been achieved. The overall working capacity of the OPT PECVD tool has been analysed and it was concluded that chamber design modification are essential for the system to work in a multidisciplinary field to avoid serious chamber contamination and 10% efficient a:Si:H benchmarks.
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Herodotou, Stephania. "Zirconium doped zinc oxide thin films deposited by atomic layer deposition." Thesis, University of Liverpool, 2015. http://livrepository.liverpool.ac.uk/2013045/.
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Doped zinc oxide is of interest as a transparent conductive oxide (TCO), due to the abundance of its major constituents, its low resistivity, high transparency and wide bandgap. The current work focuses on the properties required for TCO applications including resistivity of ≤10-3 Ω•cm, carrier density of ≥1020 cm-3, and transparency >80% in the visible light. Zirconium (Zr4+) was chosen as the dopant in the current work due to its abundance, comparable ionic size to Zn and because it can act as a double donor providing up to two extra free electrons per ion when substituted for Zn2+. The doping process can be controlled using atomic layer deposition (ALD), with the doped films resulting in an increased conductivity. The films in the current work resulted in a minimum resistivity of 1.44×10-3 Ω•cm and maximum carrier density of 3.81×1020 cm-3 for films <100 nm thickness, having 4.8 at.% Zr concentration. The resistivity was further reduced after reducing the interfacial and grain boundary scattering (i.e. increase grain size), by increasing the overall film thickness. The resistivity of 7.5×10-4 Ω•cm, carrier mobility of 19.6 cm2V‒1s-1 and carrier density of 4.2×1020 cm-3 were measured for a 250 nm thick film with 4.8 at.% doping. The tuning of the carrier density via doping offers control over the optical gap due to the net effect of Burstein-Moss effect and bandgap renormalisation. This resulted to an increase of the optical gap from 3.2 eV for the un-doped ZnO to 3.5 eV for 4.8 at.% Zr-doped films. The average optical transparency in the visible/near IR range was as high as 91% for 4.8 at.% doped films. The thickness increase also resulted in a grain orientation shift from perpendicular to the substrate (i.e. polar c-plane orientation) to parallel (i.e. non-polar m-plane) due to the strain increase that forced the films to grow at a low strain energy direction. This offers the possibility of growing non-polarised films that show no piezoelectric field charge observed in polar oriented films. Therefore, controlling the grain size through the number of ALD cycles can effectively result in mobility and preferred orientation control, while the doping concentration controls the resistivity, optical bandgap and transparency of the films.
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Mingard, Kenneth Philip. "Stucture and properties of sputter deposited Y-Ba-Cu-O thin films." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276884.
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Plassmeyer, Paul. "Metal-Oxide Thin Films Deposited from Aqueous Solutions: The Role of Cation/Water Interactions." Thesis, University of Oregon, 2017. http://hdl.handle.net/1794/22295.
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Metal-oxide thin films are used in a wide variety of electronic devices. Although many techniques have been developed to deposit thin films of metal oxides, there is still a need for alternative cost- and energy-effective deposition methods. Deposition of metal oxide thin films from aqueous solutions of all-inorganic metal salts is a viable method that meets these needs. Although many aqueous-deposited metal-oxide thin films have been successfully incorporated into functioning devices, many of the mechanisms that occur as precursors transition to metal oxides are not well understood.
The work presented in this dissertation is primarily concerned with examining the processes that occur as metal oxide thin films form from spin-deposited aqueous precursor solutions with a particular focus on the role of H2O in these processes. Chapter I summarizes methods for thin film deposition, and describes the use of aqueous metal salt solutions as viable precursors for the deposition of metal oxide thin films. Chapter II investigates the precursor chemistry, film-formation processes and properties of LaAlO3 thin films deposited from aqueous precursors. This chapter also serves as general guide to the processes that occur as metal-oxide thin films form from spin-deposited aqueous precursors. Chapters III and IV focus on the effects of H2O(g) during spin-deposition of precursor thin films and during the annealing process in which precursors are converted to metal oxides, respectively. The presence of H2O(g) during spin-deposition has a striking effect on the thickness of the resulting thin films and also affects the elemental gradient and density profiles. During annealing, H2O(g) reduces the temperatures at which counterions are expelled and influences the metal-hydroxide framework formation and its condensation to a metal oxide. The data also indicate that H2O(g) enhances diffusion of gaseous byproducts from within the films. Chapter V focuses on precursor concentration and its impact on the thermal evolution of thin films. The processes involved in the conversion of precursors to metal oxide thin films occur at lower temperatures as precursor concentration decreases. Although this is likely in part due to thickness effects, concentration-dependent precursor speciation may also be involved in lowering the temperatures at which films densify.2019-02-17
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Dowling, Andrew John, and andrewjohn3055@yahoo com. "Novel strategies for surface micromachining TiN thin films deposited by filtered arc." Swinburne University of Technology. Industrial Research Institute Swinburne, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20051129.085933.
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TiN is used commercially as a wear resistant coating on cutting tools and as a diffusion
barrier in microelectronics. TiN has gained increased interest as a material for MEMS,
however there has been very little work carried out in the area of patterning and releasing TiN for use as a structural MEMS material.
This thesis presents an investigation into the patterning and release of filtered arc deposited TiN thin films using surface micromachining techniques. Two novel strategies are presented for patterning TiN thin films and are achieved using excimer laser micromachining and photolithographic wet-etching.
TiN was deposited onto single crystal Si and Cr and Cu sacrificial layers on Si. The use of Cr as a sacrificial layer was found to facilitate the best quality patterning of the TiN and hence the majority of the work involved using Cr sacrificial layers.
TiN was deposited using partial filtration and full filtration and differences in the ability
to selectively laser pattern the TiN from the Cr sacrificial layer are presented. Various
analytical techniques were employed to investigate the origin of the difference in laser
patterning the TiN thin films.
The establishment of TiN and Cr as a novel material combination for surface micromachined MEMS was extended by etching the Cr sacrificial layer to facilitate the release of TiN stress-measurement structures.
The major finding of this thesis is that filtered arc deposited TiN thin film on Cr can be
used as a material combination to surface micromachine freestanding TiN structures as
high quality patterning and etch selectivity can be achieved using both excimer laser
micromachining and photolithographic wet-etching.
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Dunlop, Luke Arthur. "Investigation and comparison of oxide thin films deposited via two low temperature atmospheric pressure routes." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609263.
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Park, Jung Hyun. "Microstructure development and evolution of sputter deposited indium thin films in cryogenics." Auburn, Ala., 2007. http://repo.lib.auburn.edu/07M%20Theses/PARK_JUNG-HYUN_51.pdf.
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Park, Jung Hyun Kim Dong Joo. "Microstructure development and evolution of sputter deposited indium thin films in cryogenics." Auburn, Ala., 2007. http://repo.lib.auburn.edu/07M%20Theses/PARK_JUNG-HYUN_51.pdf.
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Aguirre, Brandon A. "Microstructure and electrical performance of sputter-deposited Hafnium oxide (HfO₂) thin films." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Abou, Mourad Houssam. "Metallic to insulating transition in disordered pulsed laser deposited silicide thin films." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001000.
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Jehanathan, Neerushana. "Thermal stability of plasma enhanced chemical vapor deposited silicon nitride thin films." University of Western Australia. School of Mechanical Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0069.
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[Truncated abstract] This study investigates the thermal stability of Plasma Enhanced Chemical Vapor Deposited (PECVD) silicon nitride thin films. Effects of heat-treatment in air on the chemical composition, atomic bonding structure, crystallinity, mechanical properties, morphological and physical integrity are investigated. The chemical composition, bonding structures and crystallinity are studied by means of X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared (FTIR) Spectroscopy and Transmission Electron Microscopy (TEM). The mechanical properties, such as hardness and Young’s modulus, are determined by means of nanoindentation. The morphological and physical integrity are analyzed using Scanning Electron Microscopy (SEM) . . . The Young’s modulus (E) and hardness (H) of the film deposited at 448 K were measured to have E=121±1.8 GPa and H=11.7±0.25 GPa. The film deposited at 573 K has E=150±3.6 GPa and H=14.7±0.6 GPa. For the film deposited at 573 K, the Young’s modulus is not affected by heating up to 1148 K. Heating at 1373 K caused significant increase in Young’s modulus to 180∼199 GPa. This is attributed to the crystallization of the film. For the film deposited at 448 K, the Young’s modulus showed a moderate increase, by ∼10%, after heating to above 673 K. This is consistent with the much lower level of crystallization in this film as compared to the film deposited at 573 K. In summary, low temperature deposited PECVD SiNx films are chemically and structurally unstable when heated in air to above 673 K. The main changes include oxidation to SiO2, crystallization of Si3N4 and physical cracking. The film deposited at 573 K is more stable and damage and oxidation resistant than the film deposited at 448 K.
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Juncker, Christophe Rene Henri. "Ultrafast Photocarrier Relaxation Mechanisms in Sputter-Deposited CdTe Quantum Dot Thin Films." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/193596.
Full textAbstract:
Photocarrier relaxation mechanisms in CdTe quantum dots in the strong confinement regime were investigated using femtosecond pump-probe measurements. The quantum dots were formed in films deposited on silica substrates using a sequential RF magnetron sputtering process with heat treatment to grow crystallites of various sizes. Size selection was achieved by tuning the laser to various wavelengths across the first excitation transition. The recombination mechanism showed a biexponential decay, which was fitted to a three-level model. It was shown that recombination occurs increasingly through the intermediate energy level as the size of the dots decreases. The nature of the intermediate level and the role of Auger recombination is discussed.
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Rahim, Mohammad Rezaur. "Electrical and optical properties of vacuum-deposited Mn/SiOâ†x thin films." Thesis, Brunel University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357650.
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O'Kane, Chris. "Optimisation of RF magnetron sputter deposited calcium phosphate (Ca-P) thin films." Thesis, University of Ulster, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.535139.
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Maritz, E. J. (Erasmus Jacobus). "Flux creep in pulsed laser deposited superconducting YBa₂Cu₃O₇ thin films." Thesis, Stellenbosch : University of Stellenbosch, 2002. http://hdl.handle.net/10019.1/6394.
Full textAbstract:
Thesis (PhD (Physics))--University of Stellenbosch, 2002.Includes bibliography.
ENGLISH ABSTRACT: High temperature superconductivity is an important topic in contemporary solid state physics, and an area of very active research. Due to it’s potential for application in low temperature electronic devices, the material has attracted the attention of researchers in the electronic engineering and material science fields alike. Moreover, from a fundamental point of view, several questions remain unanswered, related to the origin of superconductivity of this class of materials and the nature of quantised magnetic flux present in magnetised samples. In this work, flux creep phenomena in a thin superconducting YBa₂Cu₃O₇ film deposited by pulsed laser deposition, is investigated near the critical temperature 0 ≤ Tc – T ≤ 10 K. Creep activation energy U0 and critical current density jc were determined as a function of temperature close to Tc, providing important data to a problem of high-Tc superconductivity which is still a matter of debate. In particular it is still an open question whether restoring the temperature in a creep freezing experiment in fact restores the film to it's original state before the freezing. The most important novel results concern the regime of critical fluctuations in the vicinity Tc - T < 1 K. We studied the isothermal relaxation of trapped magnetic flux, and determined that the long time decay follows a power law, where the exponent is inversely proportional to the creep activation energy. The temperature dependence of the critical current density jc(T) of the YBa₂Cu₃O₇ film close to Tc was obtained during warming runs. It was determined that jc(T) follows a square root dependence on T to high accuracy in the range 0.2 ≤ Tc – T ≤ 1.5 K. During flux creep experiments an interesting phenomenon called creep freezing related to the strong temperature dependence of the relaxation rate was observed. A pronounced slowing of relaxation with only a small drop in temperature from a starting temperature close to Tc was detected. Experiments were conducted by initiating an isothermal flux decay run. At a certain point the temperature was slightly lowered, and the flux decay stopped within experimental accuracy. When the temperature was restored to the initial value, the flux decay resumed at the previous rate before cooling. An argument based on vortex drift velocity was employed to explain the phenomenon qualitatively. During the course of this investigation, a pulsed laser deposition (PLD) system was designed and built from scratch. PLD involves the interaction of a focussed laser pulse with a multielemental solid target material. Material ablated from the target forms a fast moving plume consisting of atomic and molecular particles, directed away from the target, and towards a usually heated substrate on which the particles condense layer by layer to form a thin film. The substrate temperature and background gas are carefully controlled to be conductive to the growth of a desired phase of the multi-elemental compound. The PLD system proved to be quite versatile in the range of materials that could be deposited. It was used to deposit thin films of different materials, most notable were good quality superconducting YBa₂Cu₃O₇, thermochromic VO2, and magnetoresistive LaxCa1-xMnO3. Metallic Au and Ag layers were also successfully deposited on YBa2Cu3O7 thin films, to serve as protective coatings. The critical temperatures of the best superconducting films were 90 K as determined by resistivity measurement. The optimal deposition conditions to deposit high quality superconducting YBa₂Cu₃O₇ thin films was found to be: deposition temperature 780°C, laser energy density 2-3 J/cm2, oxygen partial pressure 0.2 mbar, and target-substrate distance 35 mm. This yields film with Tc ~ 90 K. It was found that deposition temperature plays the predominant role in determining the quality of YBa₂Cu₃O₇ thin films deposited by PLD.
AFRIKAANSE OPSOMMING: Hoë temperatuur supergeleiding is tans ’n aktuele onderwerp van vastetoestandfisika en dit is ’n gebied van baie aktiewe navorsing. Weens die potensiaal vir toepassings van hoë temperatuur supergeleiers in elektronika, het dié klas materiale die aandag van fisici and elektronici getrek. Verskeie fundamentele vraagstukke bly steeds onbeantwoord, veral met betrekking tot die oorsprong van supergeleiding in hierdie materiale en die gedrag van gekwantiseerde magnetiese vloed (“vortekse”) in gemagnetiseerde monsters. In hierdie werk word diffusie van vortekse in dun supergeleidende YBa₂Cu₃O₇ films ondersoek naby die kritieke temperatuur (0 ≤ Tc - T ≤ 10 K). Die temperatuur afhanklikheid van die diffusie aktiveringsenergie U0 en die kritieke stroomdigtheid jc word bepaal naby Tc. Dit verskaf belangrike inligting tot probleme in hoë temperatuur supergeleiding wat tans nog onbeantwoord bly. In die besonder is dit steeds ’n ope vraag of die herstel van die aanvanklike temperatuur in ’n vloedstollings eksperiment waarlik die film tot die oorspronklike toestand herstel. Die belangrikste nuwe resultate hou verband met die gebied van kritieke fluktuasies van die orde parameter in die omgewing 0 < Tc - T < 1 K. Ons het die isotermiese ontspanning van vortekse verstrik in die kristalstruktuur bestudeer, en bepaal dat die lang tydsverval ’n magsverwantskap handhaaf, waar die eksponent omgekeerd eweredig is aan U0. Die temperatuur afhanklikheid van die kritieke stroomdigtheid jc(T) van die YBa₂Cu₃O₇ film naby Tc is bepaal tydens verhittingslopies. Daar is bevind dat naby Tc, jc ’n vierkantswortel verband met T volg, tot hoë noukeurigheid in die gebied 0.2 ≤ Tc – T ≤ 1.5 K. Gedurende vorteksdiffusie eksperimente is ’n interessante verskynsel naamlik vloedstolling (“flux freezing”) waargeneem. Dit hou verband met die sterk temperatuur afhanklikheid van die vervaltempo van die magnetiese moment van ’n gemagnetiseerde film. ’n Skerp daling van die vervaltempo, weens slegs ’n klein temperatuurdaling vanaf die begin temperatuur naby Tc, is waargeneem. Gedurende eksperimente is daar aanvanklik ’n isotermiese vloedontspanning teweeg gebring. Op ’n sekere tydstip is die temperatuur effens verlaag, waarby die vloedontspanning tot stilstand gekom het binne grense van waarneming. Wanneer die temperatuur weer herstel is na die oorspronklike, het die vloedontspanning voortgegaan teen die tempo voor die temperatuurverlaging. ’n Verklaring wat gebaseer is op vorteks dryfsnelheid was aan die hand gedoen om hierdie gedrag te verklaar. ’n Groot komponent van die projek was om die dun YBa₂Cu₃O₇ films self te vervaardig. Tydens hierdie ondersoek, is ’n gepulseerde laser deposisie (“PLD”) sisteem eiehandig ontwerp en gebou. PLD behels die interaksie van ’n gefokuseerde laser puls met ’n teiken bestaande uit ’n multi-element vastestofverbinding. Materiaal wat verdamp (“ablate”) word, vorm ’n snelbewegende pluim bestaande uit atomiese en molekulêre deeltjies. Dit beweeg vanaf die teiken na ’n verhitte substraat, waarop die deeltjies kondenseer om laag vir laag ’n dun film te vorm. Die substraat temperatuur en agtergrond gas word sorgvuldig beheer om die groei van die verlangde fase van die multi-element verbinding teweeg te bring. Die PLD sisteem is baie veeldoelig ten opsigte van die verskeidenheid materiale wat suksesvol neergeslaan kan word. Dit was aangewend om verskillende materiale neer te slaan, onder andere supergeleidende YBa₂Cu₃O₇, termochromiese VO2, en magnetoresistiewe LaxCa1-xMnO3. Geleidende Au en Ag lagies is ook suksesvol neergeslaan op YBa₂Cu₃O₇ dun films, om te dien as beskermingslagies. Die kritieke temperatuur van die beste supergeleidende films was 90 K soos bepaal deur weerstandsmetings. Die optimale neerslaan toestand vir hoë kwaliteit YBa₂Cu₃O₇ dun films was: substraat temperatuur 780°C, laser energiedigtheid 2 - 3 J/cm2, suurstofdruk 0.2 mbar, en teiken-substraat afstand 35 mm. Daar is bevind dat die substraat temperatuur die deurslaggewende rol speel tydens die neerslaan proses om die kwaliteit van die supergeleidende films te bepaal.
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Hall, Gareth W. "Control of the properties of semiconducting thin films deposited using magnetron sputtering." Thesis, Loughborough University, 1993. https://dspace.lboro.ac.uk/2134/12927.
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The objective of the work was to deposit semiconducting thin films with controlled properties using unbalanced reactive magnetron sputtering. It was decided to utilise this technique because it offers high deposition rate and controllable in-situ ion bombardment of the growing film, desirable attributes from both research and production perspectives. Sputtering from a metal cathode in a reactive gas atmosphere introduces process instabilities which can result in a low degree of control over the stoichiometry, optical, electrical and structural properties of the films. Whilst the focus of the study was to achieve repeatable control over semiconducting film properties, additional areas of interest associated with the reactive sputtering process were investigated as the project developed. Improvements in magnetron design have been made to remove iron contamination from the extended poles, at the same time improving cathode utilisation. A new technique of bonding polycrystalline silicon cathodes to cooling shims has been developed using a sputtered threemetal multilayer process. DC sputtering of silicon in the presence of oxygen, nitrogen, nitrogen and oxygen, and nitrogen and air has been used to produce films of refractive index between 2.27 and 1.45 at rates between 0.5 and 2 nms-1 depending on composition. Refractive index and optical transmittance of the films have been closely controlled by varying gas flow and composition, and substitution of air for oxygen increased the sensitivity so that indices of oxy-nitride films could be tailored to one decimal place. The deposition of Indium-tin-oxide (ITO) onto glass substrates has been investigated, using a feedback control loop to control the otherwise unstable process.
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Hadley, M. J. "Magnetic and structural investigation of magnetic thin films with obliquely deposited underlayers." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246433.
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Kim, Se Jin. "Pulsed laser deposited metal oxide thin films mediated controlled adsorption of proteins." [Gainesville, Fla.] : University of Florida, 2008. http://purl.fcla.edu/fcla/etd/UFE0022878.
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FIGUEROA, NEILETH JOHANNA STAND. "STRUCTURAL AND MECHANICAL PROPERTIES OF THIN FILMS DEPOSITED FROM HEXAMETHYLDISILAZANE BY PECVD." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2014. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=24214@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
Esta dissertação teve como objetivo estudar as propriedades estruturais, mecânicas dos filmes de silício carbono nitrogenado amorfo (a-SiC:N) e a viabilidade do seu uso como camada adesiva entre filmes finos de carbono amorfo hidrogenado e aço inoxidável 316L. Os filmes de a-SiC:N foram crescidos pela técnica de deposição química na fase vapor assistida por plasma (PECVD) utilizando como precursor hexametildissilazano (HMDSN) sobre chapas de aço inoxidável 316L e lâminas de silício cristalino 100. Para a deposição foram variados os parâmetros de tensão de autopolarização (de -150V até -450V) e a temperatura de deposição (25 Graus Celsius, 200 Graus Celsius e 300 Graus Celsius). Os filmes foram caracterizados por técnicas de perfilometria, onde pudemos obter a taxa de deposição, a tensão interna dos filmes, análises por espectroscopia de fotoelétrons induzidos por raios-x (XPS) e espectroscopia de infravermelho onde identificamos a presença de ligações entre os átomos de silício, carbono e nitrogênio. Com a espectroscopia Raman observamos a presença das bandas D e G com características de filmes de carbono amorfo. As análises de nanoindentação determinaram que a dureza variou entre 8 e 12 GPa. A microscopia de força atômica evidenciou a presença de nanoestruturas sobre a superfície dos filmes. E por fim, obtivemos sucesso na deposição de filmes de carbono amorfo hidrogenado e carbono amorfo fluorado sobre chapas de aço inoxidável empregando filmes finos de a-SiC:N como camada adesiva.
The objective of this dissertation has been to study the structural and mechanical properties of amorphous SiC:N thin films and the viability of their use as adhesive layer between amorphous C:N thin films and 316L stainless steel. The a-SiC:N films were grown via Plasma-Enhanced Chemical Vapor Deposition (PECVD), using Hexamethyldisilazane (HMDSN) as precursor on 316L stainless steel and crystalline silicon substrates 100. For the deposition, the parameters changed were the self-bias (from -150V to -450V) and the deposition temperature (25 Degree Celsius, 200 Degree Celsius and 300 Degree Celius). The characterization of the films was accomplished by using profilometry techniques, used to obtain the deposition rate and the internal stress of the films, x-ray photoelectron spectroscopy (XPS) and infrared spectroscopy used to identify the presence of bonding between the Silicon, Carbon and Nitrogen atoms. The Raman spectroscopy was employed to observe the presence of the D and G bands with characteristics of amorphous carbon films. The nanoindentation analysis determined that the hardness varied between 8 and 12GPa. Atomic force microscopy (AFM) evidenced the presence of nanostructures on the surface of the films. Finally, we were able to perform deposition of hydrogenated amorphous carbon and of fluorinated amorphous carbon thin films on stainless steel substrates using a-SiC:N thin films as adhesive layer.
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Rao, K. Yellareswara. "Sputter Deposited Thin Film Cathodes from Powder Target for Micro Battery Applications." Thesis, 2015. http://etd.iisc.ernet.in/2005/3825.
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All solid state Li-ion batteries (thin film micro batteries) have become inevitable for miniaturized devices and sensors as power sources. Fabrication of electrode materials for batteries in thin film form has been carried out with the existing technologies used in semiconductor industry. In the present thesis, radio frequency (RF) sputtering has been chosen for deposition of cathode material (ceramic oxides) thin films because of several advantages such as precise thickness control and deposition of compound thin films with equivalent composition. Conventional sputtering involves fabrication of thin film using custom made pellet according to the specification of sputter gun. However several issues such as target breaking are inevitable with the pellet sputtering. To forfend the issues, powder sputtering has been implemented for the deposition of various thin film cathodes in an economically feasible approach. Optimization of various process parameters during film deposition of cathode materials LiCoO2, Li2MnO3, LiNixMnyO4, mixed oxide cathodes of LiMn2O4, LiCoO2 and TiO2 etc., have been executed successfully by the present approach to achieve optimum electrochemical performance. Thereafter the optimized process parameters would be useful for selection of cathode layers for micro battery fabrication.
Chapter 1 gives a brief introduction to the Li ion and thin film solid state batteries. It also highlights the advantages of powder sputtering compared to conventional pellet sputtering.
In Chapter 2, the materials used and methods employed for the fabrication of thin film electrodes and analytical characterizations have been discussed.
In chapter 3, implementation of powder sputtering for the deposition of LiCoO2 thin films has been discussed. X-Ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS) and electrochemical investigations have been carried out and promising results have been achieved. Charge discharge studies delivered a discharge capacity of 64 µAh µm-1 cm-2 in the first cycle in the potential range
3.0-4.2 V vs. Li/Li+. The possible causes for the moderate cycle life performance have been discussed.
Systematic investigations for RF power optimization for the deposition of Li2-xMnO3-y thin films have been carried out. Galvanostatic charge discharge studies delivered a highest discharge capacity of 139 µAh µm-1cm-2 in the potential window 2.0-3.5 V. Thereafter, effect of LMO film thickness on electrochemical performance has been studied in the thickness range 70 nm to 300 nm. Films of lower thickness delivered higher discharge capacity with good cycle life than the thicker films. These details are discussed in chapter 4.
In Chapter 5, fabrication and electrochemical performance of LiNixMnyO4 thin films are presented. LMO thin films have been deposited on nickel coated stainless steel substrates. The as deposited films were annealed at 500 °C in ambient conditions. Nickel diffuses in to LMO film and results in LiNixMnyO4 (LMNO) film. These films were further characterized. Electrochemical studies were conducted up to higher potential 4.4 V resulted in discharge capacities of the order of 55 µAh µm-1cm-2.
In chapter 6, electrochemical investigations of mixed oxide thin films of LiCoO2 and LiMn2O4 have been carried out. Electrochemical investigations have been carried out in the potential window 2.0–4.3 V and a discharge capacity of 24 µAh µm-1cm-2 has been achieved. In continuation, TiO2 powder was added to the former composition and the deposited films were characterized for electrochemical performance. The potential window as well as the discharge capacity enhanced after TiO2 doping. Electrochemical characterization has been carried out in the potential window 1.4–4.5 V, and a discharge capacity of 135 µAh µm-1cm-2 has been achieved.
Finally chapter 7 gives overall conclusions and future directions to the continuation of the work.
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Su, Kou-Hui, and 蘇國輝. "Ultrasonic Spray Pyrolysis Deposited BZT Thin Films." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/84169631962012539026.
Full textAbstract:
碩士國立成功大學
材料科學(工程)學系
84
Ultrasonic spray pyrolysis has been employed in this study to deposit BZT thin films on n-type silicon wafer using Ti(i-C3H7O)4, Zr(n-C3H7O)4 and (CH3COO)2Ba as reactants. Major experimental parametersare the substrate temperature and reaction solution relative concentration,which affect the growth rate,stoichiometric composition, refractiveindex, crystal structure, surface morphology and the electrical properties(leakage current and dielectric constant). The process is characterizedand optimized in order to obtain the best processing condition for future application. Experimental results indicate that the Ba/ZrTi atomic ratio in thin films is lower than ideal and the Ba atomic ratio increases with growth temperature.The crystal structure and surface morphology are also improved for growths high temperatures. BZT thin films deposited in high temperatures have better dielectric constant and leakage current. After annealing, the dielectric constant of BZT thin film have increased by a factor of about 2. Using water as the solvent of the Ba reactant one canraise growth rate. When the reaction solution are separately introduced into the chamber the Ba atomic ratio in the films enhanced, but the morphology, microstructure and the electrical properties of the thin films become deteriorated, because of defect generation.
47
Lin, Zhe Zhi, and 林哲治. "Studies on vacuum-deposited organic thin films." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/76644660677820020861.
Full text
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Liedtke-Grüner, Susann. "Growth of obliquely deposited metallic thin films." 2018. https://ul.qucosa.de/id/qucosa%3A33615.
Full textAbstract:
The present work represents a systematical study of the growth of columnar, metallic thin films deposited under highly oblique vapor incidence on planar substrates. Oblique angle deposition is a physical vapor deposition technique that is based on the self-shadowing effect. This enables the fabrication of highly porous thin films that are composed of three-dimensionally separated, micro-, and nano-sized columns.
For this study, metals that cover a wide range of melting points and crystal structures have been chosen, and the observed growth characteristics are compared with each other to gain information about the growth of obliquely deposited metallic thin films in general. Among the various parameters that have an influence on the growth of columnar thin films, in the focus of this work are the angle of the incoming particle flux, substrate rotation frequency, and substrate temperature as well as the influence of the residual gas atmosphere.
The first part deals with a morphological analysis of the columnar, metallic thin films by scanning electron microscopy (SEM). The columnar shape, the columnar tilt angle, and the thin film porosity are investigated depending on the incidence flux direction as well as substrate temperature and rotation. It is examined how a reduction of the substrate temperature down to 77 K - realized by a liquid nitrogen cooled sample holder - influences the growth of the columnar thin films. Further, it is analyzed how substrate rotation influences the local deposition geometry and accordingly the growth behavior of tilted columns, spirals, screws, and upright columns. Based on geometrical considerations, a theoretical model is proposed and compared with the made observations.
The second part focusses on the high-resolution local structure analysis of individual columns via (scanning) transmission electron microscopy (TEM). On the one hand, the columnar structure is analyzed depending on the substrate temperature and substrate rotation via high resolution TEM. On the other hand, the crystallinity of individual columns is studied along the entire column by nanobeam electron diffraction. This technique is also applied to gain information about the orientation of the crystallites at the substrates surface and to investigate the selection processes of crystalline orientations during the growth. Moreover, the presented studies reveal under which conditions single crystalline columns are forming.
In the final part, the texture of the columnar, metallic thin films is analyzed depending on the film thickness, the angle of the incoming particle flux as well as on the substrate temperature. X-ray diffraction (XRD) measurements, such as pole figures, are applied to determine the orientation of the lattice planes in the columns depending on the incident flux direction and on the substrate temperature. The observations are backed by reflection high-energy electron diffraction (RHEED) investigations. A model is developed that enables to explain why the tilt of the lattice directions in the columns is not equal to the tilt angle of the columns. A further theoretical model is introduced that enables to roughly estimate the tilt angle of the lattice direction that ensures the fastest vertical columnar growth.:1 MOTIVATION 7
2 BASICS OF OBLIQUE ANGLE DEPOSITION 9
2.1 Thin film growth by oblique deposition 9
2.1.1 Physical vapor deposition 9
2.1.2 Nucleation 10
2.1.3 Shadowing 11
2.1.4 Structure of individual columns 12
2.2 Sculpturing thin films on the nanometer scale 13
2.2.1 Angle of the incoming particle flux 13
2.2.2 Substrate rotation 16
2.2.3 Substrate temperature 17
2.3 Application areas for metallic nanostructured thin films 20
3 EXPERIMENTAL DETAILS 23
3.1 Sample fabrication 23
3.1.1 General deposition system setup and evaporation process 23
3.1.2 Crucibles, substrates, and sample holders 25
3.1.3 Controlling substrate movement and temperature 26
3.1.4 Controlling film thickness and deposition rate 29
3.2 Sample characterization 30
3.2.1 Scanning electron microscope (SEM) 30
3.2.2 Transmission electron microscopy (TEM) 31
3.2.3 X-Ray Diffraction (XRD) and In-Plane Pole Figure measurements (IPPF) 33
3.2.4 Reflection high-energy electron diffraction (RHEED) 36
3.2.5 Raman scattering spectroscopy 36
4 MORPHOLOGICAL ANALYSIS OF COLUMNAR THIN FILMS 39
4.1 Oblique angle deposition 40
4.1.1 Deposition at room temperature 40
4.1.2 Deposition at different temperatures 43
4.2 Glancing angle deposition 61
4.2.1 Continuous substrate rotation 61
4.2.2 Discrete substrate rotation 66
4.3 Summary of results 69
5 STRUCTURAL ANALYSIS OF INDIVIDUAL COLUMNS 71
5.1 Oblique angle deposition 71
5.1.1 Tilted columns grown at room temperature 71
5.1.2 Tilted columns grown at different substrate temperatures 78
5.2 Glancing angle deposition 82
5.2.1 Vertical columns grown by continuous substrate rotation 82
5.2.2 Zigzag columns grown by discrete substrate rotation 85
5.3 Discussion 87
5.4 Summary of results 89
6 TEXTURE ANALYSIS OF COLUMNAR THIN FILMS 91
6.1 Influence of the film thickness 91
6.2 Influence of the incoming flux direction 99
6.3 Influence of the substrate temperature 110
6.4 Summary of results 116
7 SUMMARY AND CONCLUSIONS 119
8 LIST OF LITERATURE 123
9 LIST OF ABBREVIATIONS 134
10 LIST OF VARIABLES AND CONSTANTS 136
11 ACKNOWLEDGEMENTS 139
PUBLICATION LIST 140
SELBSTSTÄNDIGKEITSERKLÄRUNG 143
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Gomes, Isabel Alexandra Domingues Tarroso. "Manganite thin films deposited on piezoelectric substrates." Doctoral thesis, 2013. http://hdl.handle.net/1822/27324.
Full textAbstract:
Tese de doutoramento Programa Doutoral em Física (MAP-FIS)O interesse crescente em conseguir controlar a magnetização de materiais magnéticos através de campos eléctricos, para aplicações em spintrónica, levou ao desenvolvimento de compósitos magnetoeléctricos com diversas geometrias e composiçoes. Entre estas estruturas compósitas encontram-se os lmes nos de manganites com magnetorresistência colossal depositados sobre substratos piezoeléctricos. Estas estruturas permitem, por um lado, tirar partido do facto de as manganites com magnetorresistência colossal serem particularmente sensíveis aos efeitos de deformação e, por outro, da possibilidade de controlar de maneira reversível a deformação imposta aos lmes e, consequentemente, a sua magnetização, por meio da utilização de substratos piezoeléctricos. Neste trabalho, lmes nos da manganite ferromagnética e metálica La0:67Sr0:33MnO3 (LSMO), com alta largura de banda, e da manganite com ordenamento de carga e baixa largura de banda Pr0:50Ca0:50MnO3 (PCMO) foram depositados em substratos cristalinos piezoeléctricos de LiNbO3 e 0.68Pb(Mg1=3Nb2=3)O3 0.32PbTiO3 (PMN-PT). Foi feita uma caracterização detalhada das suas propriedades estruturais, magnéticas e de transporte eléctrico. Os lmes de LSMO depositados sobre LiNbO3 eram fortemente orientados, com uma direcção preferencial de crescimento (111) pseudocúbica. Veri cou-se, nos lmes, uma transição paramagnética-ferromagnética, com temperaturas de Curie entre 265 K e 360 K, e resistividades eléctricas de baixa temperatura na gama 0:15 0 4:5 .cm. Nestas amostras veri cou-se que a temperatura de deposição afectou as propriedades dos lmes produzidos, no sentido em que um aumento da temperatura de deposição de 600 C para 690 C aumentou a temperatura de Curie de 265 K para 330 K e originou um comportamento metálico. O comportamento da magnetorresistência variou com o aumento da temperatura de deposição, tendo-se observado a supressão da acentuada magnetorresistência de baixo campo. Esta tinha um valor aproximado de -15%, e tinha surgido no lme depositado a 600 C devido ao efeito túnel através das fronteiras de grão, que é dependente do spin. Isto foi também observado nas medidas de magnetorresistência anisotrópica. Nos lmes nos de LSMO sobre substratos ferroeléctricos de PMN-PT do tipo relaxor , foi observado um crescimento com orientação pseudocúbica (001). Foram também observados pequenos incrementos na magnetização abaixo da temperatura de Curie TC = 340 K. Veri cou-se uma correlação entre estas variações na magnetização dos lmes e variações na constante dieléctrica dos substratos, o que sugere um acoplamento magnetoeléctrico. A resistência eléctrica dos lmes foi medida em função do campo eléctrico aplicado ao substrato, o que mais uma vez mostrou um acoplamento através da deformação piezoeléctrica. A maior taxa de variação da resistência obtida foi de 10 /V. Este valor foi medido na zona de baixo campo eléctrico, i.e., onde a deformação é reversível. Os lmes nos de PCMO depositados sobre LiNbO3, orientados segundo c, possuíam também uma orientação (111) pseudocúbica. O seu parâmetro de rede variou sistematicamente com a sua espessura. A fase com ordenamento de carga foi estabilizada nestes lmes e a temperatura TCO a qual ela ocorreu encontrava-se na gama 210 TCO 240 K. Para além disso, TCO aumentou com o decréscimo da espessura dos lmes, devido a deformação epitaxial induzida pelo seu crescimento. A magnetorresistência do PCMO depositado num substrato de LiNbO3 orientado segundo c foi medida numa unidade de campos magnéticos pulsados. Foi observada uma transição de uma fase metálica com cargas desordenadas, para uma fase isoladora com ordenamento de carga. Esta transição ocorreu a um campo crítico H c = 2:3 T a temperatura de 200 K, numa medida efectuada em campo magnético decrescente. Finalmente, os lmes nos de PCMO depositados em PMN-PT eram orientados, com uma orientação preferencial de crescimento (001) pseudocúbica. Foi observado o controlo piezoeléctrico da resistência eléctrica. A taxa de variação da resistência eléctrica dos lmes foi de 11 /V na região reversível da curva de deformação em função do campo eléctrico aplicado.
The growing interest in controlling the magnetization by electric elds for spintronics applications has led to the development of magnetoelectric composites with diverse geometries and compositions. Among these composite structures are colossal magnetoresistive manganite thin lms deposited on piezoelectric substrates. Colossal magnetoresistive manganites, on the one hand, are particularly sensitive to the e ects of strain, making them good candidates for incorporation in magnetoelectric composites. On the other hand, piezoelectric substrates allow for a reversible control of the strain applied to the lms, and therefore of the magnetization. In this work, high-bandwidth ferromagnetic metallic manganite La0:67Sr0:33MnO3 (LSMO) and low-bandwidth charge-ordered Pr0:50Ca0:50MnO3 (PCMO) were deposited on LiNbO3 and 0.68Pb(Mg1=3Nb2=3)O3 0.32PbTiO3 (PMN-PT) single crystal piezoelectric substrates. A detailed characterization of the structural, magnetic and transport properties of the produced samples has been performed. The LSMO thin lms on LiNbO3 were highly oriented, with a pseudocubic (111) preferred growth direction. The lms were ferromagnetic with Curie temperatures between 265 K and 360 K and low temperature resistivity values in the range 0:15 0 4:5 .cm. In these samples the deposition temperature was seen to a ect the properties of the deposited lms, in the sense that an increase in the deposition temperature from 600 C to 690 C strongly enhances the ferromagnetic Curie temperature from 265 K to 330 K and increases metallic conduction. The magnetoresistance behaviour is also modi ed as the deposition temperature is increased, with the suppression of the low eld magnetoresistance due to spin polarized tunnelling across grain boundaries. This is con rmed by the measurements of anisotropic magnetoresistance. In the LSMO thin lms deposited on the relaxor ferroelectric PMN PT a pseudocubic (001)-oriented growth was observed. Slight increases in the magnetization, below the Curie temperature TC = 340 K, were observed in the lms. These variations were found to correlate with variations in the dielectric constant of the substrate, suggesting a magnetoelectric coupling. The electrical In the LSMO thin lms deposited on the relaxor ferroelectric PMN PT a pseudocubic (001)-oriented growth was observed. Slight increases in the magnetization, below the Curie temperature TC = 340 K, were observed in the lms. These variations were found to correlate with variations in the dielectric constant of the substrate, suggesting a magnetoelectric coupling. The electrical In the LSMO thin lms deposited on the relaxor ferroelectric PMN PT a pseudocubic (001)-oriented growth was observed. Slight increases in the magnetization, below the Curie temperature TC = 340 K, were observed in the lms. These variations were found to correlate with variations in the dielectric constant of the substrate, suggesting a magnetoelectric coupling. The electrical In the LSMO thin lms deposited on the relaxor ferroelectric PMN PT a pseudocubic (001)-oriented growth was observed. Slight increases in the magnetization, below the Curie temperature TC = 340 K, were observed in the lms. These variations were found to correlate with variations in the dielectric constant of the substrate, suggesting a magnetoelectric coupling. The electrical resistance of the lms was measured as a function of the electric eld applied to the substrate, once again showing a coupling via piezoelectric strain. The resistance varied up to 10 /V in the low electric eld region, i.e., where the strain is reversible. The PCMO thin lms deposited on z-cut LiNbO3 were also pseudocubic (111)-oriented. Their pseudocubic lattice parameter varied systematically with lm thickness. The charge-ordered phase was stabilized in the lms and the temperature TCO at which it occurs was in the range 210 TCO 240 K. Moreover, TCO increased with decreasing lm thickness due to thickness-induced strain in the lms. The magnetoresistance of a PCMO lm on z-cut LiNbO3 was measured with pulsed magnetic elds. The critical magnetic eld at which the crossover from the charge-disordered, metallic phase to the charge-ordered phase was measured in decreasing eld, and the obtained value was H c = 2:3T at 200 K, much smaller than in previous studies of lms on SrTiO3 or LaAlO3. If this corresponds to a lower value for the charge ordering melting eld, it can make the PCMO thin lms on LiNbO3 more suitable for applications. Finally, the thin lms of PCMO deposited on PMN-PT were oriented, with a preferred pseudocubic (001) growth direction. A piezoelectric control of the electrical resistance of the lms was observed. The variation of the electrical resistance with the applied electric eld was around 11 /V in the reversible region of the strainelectric eld curve.
50
Kuo-ChengChen and 陳國政. "Functional Nanocomposite Thin Films Deposited by Plasma Deposition." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/50052498308210268277.
Full textAbstract:
博士國立成功大學
化學工程學系碩博士班
100
Diamond-like carbon (DLC) nanocomposite films containing nanostructures were synthesized by various deposition techniques, including inductively-coupled plasma chemical vapor deposition (ICP-CVD), sputtering-assisted CVD, capacitive-coupled plasma CVD, plasma jet CVD etc. By incorporating high densities of ceramic nanoparticles (SiC, Si3N4, ZrO2, TiC, TiO2, ZnO, etc.) and nano-carbons, DLC nanocomposites can present the increase of film hardness and the reduction of film stress, as well as the enhancement of toughness, increase of film adhesion, and decrease of friction coefficients with novel function of light-induced hydrophilicity. SiCxNy nanocrystallites-containing DLC nanocomposite films were prepared by ICP-CVD using a hexamethyldisilazane (HMDSN) precursor. The substrate was biased by a pulsed-DC power supply to provide the necessary energy of deposited ions. The effects of substrate bias on the surface morphology, roughness, and the mechanical properties of nanocomposite film were well investigated. The results revealed the film has maximum hardness of 15 GPa at a relative low stress of 0.5 GPa at an ICP power of 100W, and a substrate bias of -200V. The films exhibited a lower coefficient of friction in the range of 0.06 to 0.09 via nano-scratch technique, and had lower wear depth with a good wear performance using nano-wear test. The fracture toughness of the film was greatly enhanced by the incorporation of SiCxNy nanoparticles in the DLC matrix, measured from its resistance to crack propagation by the indentation method of Vickers indenter. Zirconia-containing DLC nanocomposite films were prepared by sputtering-assisted plasma CVD. ZrO2-DLC films were deposited using acetylene as the carbon source, and argon was used to sputter ZrO2 target. AFM results show that the surface of the films is very smooth. The tribological properties of the films could be controlled by adjusting the substrate biases during depositions. A higher energy of ion bombardment in this system biasing by pulsed-DC, induces the formation of sp2 carbon bonding in the film and makes the films’ hardness and Young’s modulus drop. The fractured toughness of DLC nanocomposite films measured by Vickers indenter were in the range from 14 to 22 MPa•m1/2, revealing the enhancement of film toughness. Nano-carbons embedded in DLC nanocomposite films were synthesized by plasma jet CVD in the mixed gases of benzene and nitrogen. Transmission electron microscopy images of the films indicate the existence of nanostructured carbon. A high degree of dissociation and reaction in plasma jet reactor and appropriate nitrogen contents in the gas phase are important for the growth of nanostructured carbon embedded in the DLC matrix. Synthesis of TiO2-DLC nanocomposite films with novel functions were studied by sputtering-assisted plasma CVD. With titanium-oxygen species sputtered from titania (TiO2) target by argon using a radio-frequency (RF) power, DLC films were simultaneously grown on the negatively-biased substrate by plasma CVD of acetylene gas using a pulsed direct-current (DC) power. By adjusting the sputtering power, both TiO2 and TiC nanoparticles could be incorporated in the DLC films. The TiO2-DLC nanocomposite films deposited at 80.7 % Ar exhibited a high hardness of around 14 GPa at a relatively low stress and, particularly, a fast rate of turning super-hydrophilic by reaching zero degree of water contact angle under 40 minutes of ultraviolet irradiation. Synthesis of amorphous boron nitride films (a-BN) at low temperature were studied by hollow cathode discharge CVD. Borazine and N2 gases were employed as the precursors to deposit a-BN films. The as-deposited films were amorphous phase with a transparent and smooth surface. Fourier transform infrared spectroscopy (FTIR) revealed that with a high nitrogen concentration and a high hollow cathode power, high content of sp3-bonded BN can be obtained. Hollow cathode plasma was essential in forming the sp3-bonded BN in the film.