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Dissertations / Theses on the topic 'High-Density thin films'
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Modi, Mitul B. "Fracture in stress engineered, high density, thin film interconnects." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/16336.
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Song, Yoon-Jong. "Ferroelectric Thin Films for High Density Non-volatile Memories." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30675.
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Ferroelectric random access memories (FRAM) are considered as future memories due to high speed, low cost, low power, excellent radiation hardness, nonvolatility, and good compatibility with the existing integrated circuit (IC) technology. The non-volatile FRAM devices are divided into two categories, based on reading technique: destructive readout (DRO) FRAM and non-destructive readout (NDRO) FRAM.
Lead zirconate titanate (PZT) is recently considered as one of the most promising materials for DRO FRAM devices due to its excellent ferroelectric properties. There are remarkable advances in the applications of PZT thin films, but the direct integration into high density CMOS devices is restricted by high processing temperatures. Hence, it is desirable to lower processing temperature and develop novel high temperature electrode-barrier layers for achieving high density DRO FRAM devices.
The NDRO FRAM devices have been developed mainly using metal-ferroelectric-semiconductor (MFS) and metal-ferroelectric-metal-insulator-semiconductor (MFMIS) structure. This devices use the remanent polarization of ferroelectric films to control the surface conductivity of a silicon substrate. The problem of the NDRO FRAM is that the actual electric field applied to ferroelectric films is very small compared to the external electric field, because of the large depolarization field in the MFS structure and the high capacitance ratio of ferroelectric capacitor and SiO2 capacitor in series in the MFMIS structure. Since the typical ferroelectric films show very high dielectric constant over 400, it is desired to develop ferroelectric films with low dielectric constant and low coercive electric field.
This research is primarily focused on developing low temperature processing and high temperature electrode-barrier layers for DRO FRAM application, and exploiting novel ferroelectric materials for NDRO FRAM application. The low temperature processing was achieved by a novel sol-gel processing, which takes advantage of in-situ electrode template layer, rapid heating-treatment without pyrolysis step, and molecularly modified precursors. The PZT films with various composition were also investigated as a function of Ti content. In order to study the integration issues for these PZT films, a substrate was constructed as Pt/TiN/TiSi2/poly-Si, which represents a scheme of capacitor in high density DRO FRAM devices. The ferroelectric films were incorporated into the substrate, and their ferroelectric properties were investigated as a function of annealing temperature. Excellent ferroelectric properties were observed for the thin films processed at a low temperature of 500 °C as contacting between top Pt and bottom polysilicon.
The other approach we have taken to overcome the integration problems in high density DRO FRAM devices is to develop high temperature electrode barrier layers. In this research, Pt/IrO2/Ir hybrid layers were prepared on poly-Si substrate as high temperature electrode-barriers. The PZT films fabricated on the Pt/IrO2/Ir/poly-Si substrates exhibited good ferroelectric properties and outstanding fatigue properties after high temperature processing. It was observed from Auger electron spectroscopy (AES) profiles that the hybrid oxide electrode minimized fatigue problem by reducing the oxygen vacancies entrapment at the electrode/ferroelectric interfaces. This results indicated that Pt/IrO2/Ir high temperature electrode-barrier layers promise to solve major problems of PZT integration into high density DRO memory devices.
For the NDRO FRAM devices, Sr2Nb2O7 and La2Ti2O7 thin films were prepared on Pt-coated silicon, Si(100), and Pt/IrO2/SiO2/Si substrates by metalorganic deposition (MOD) technique. The Sr2Nb2O7 and La2Ti2O7 thin films showed the dielectric constant values of 48 and 46, respectively. However, no ferroelectricity was observed at room temperature, which might be attributed to extremely small grains. Extensive studies on preparation and properties of Sr2(Ta1-xNbx)O7 (STN) both in bulk and thin film form were carried out as a function of composition. The STN films exhibited small dielectric constant of around 46, irrespective of the composition.Ph. D.
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Balu, Venkatasubramani. "Barium strontium titanate thin film capacitors for high-density memories /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Wan, Jun. "Iron-platinum granular films for ultra-high density recording." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 178 p, 2009. http://proquest.umi.com/pqdweb?did=1674099591&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Sharpe, Alton Russell. "Functional validation of a novel technique for assembling high density polyimide cochlear implants." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45741.
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It has been hypothesized that increasing the number of active sites on a cochlear implant electrode array will enable the recipient to distinguish a higher number of pitch precepts, thus creating a more natural sound. While DSP processing strategies for cochlear implants have evolved significantly to address this, technology for the actual electrode array has remained relatively constant and limits the number of physical electrodes possible. Previous work introduced the concept of using Thin-Film Array (TFA) technology to allow for much higher site densities, although the original devices proved unreliable during surgical insertion tests. This work presents a new method of combining polyimide-based TFA's with supporting silicone insertion platforms to create assembled electrode arrays that are a more viable option for surgical insertion. The electrical and mechanical properties of these assemblies are investigated with physical deformation tests and finite element analysis in COMSOL to quantify how they will perform upon insertion into the cochlea, and the preliminary results of a surgical insertion study into human cadaveric temporal bones will be discussed.
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Lemenager, Maxime. "Atomic Layer Deposition of thin dielectric films for high density and high reliability integrated capacitors." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI085.
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Le stockage d’énergie dans les systèmes embarqués fait toujours l’objet d’importants efforts de R&D car il nécessite une constante diminution du volume occupé par les composants électroniques. Il apparaît que la taille des composants discrets que sont les condensateurs est un des freins à la miniaturisation des dispositifs finaux. Bien que des technologies, principalement basées sur la gravure profonde du silicium à l’échelle micrométrique, aient permis des avancées considérables, elles se montrent dorénavant limitées en termes de densité d’intégration. De ce fait, Murata IPS a développé une nouvelle technologie 3D à l’échelle nanométrique permettant une plus forte surface développée. L’utilisation d’une telle matrice requiert une méthode de dépôt de l’empilement MIM telle que l’ALD, adaptée aux structures à fort rapport d’aspect. Le but de cette thèse est ainsi l’intégration de la structure MIM dans la nouvelle matrice 3D dans le respect des contraintes inhérentes à l’industrie de manière à donner lieu à la cinquième génération des technologies PICS™. Le premier challenge résidait dans la conformalité des dépôts que nous nous sommes efforcés d’obtenir avec un équipement de production. Cela a permis de démontrer une densité de capacité supérieure à 1µF/mm² en utilisant un film diélectrique d’alumine de 10nm. Il s’avère également que l’intégration des électrodes TiN joue un rôle important sur la structure 3D. En effet, les contraintes ont dû être réduites pour assurer la tenue mécanique de la structure, notamment en jouant sur le pulse NH3. Les interfaces métal-diélectriques ont également fait l’objet d’une étude approfondie où l’influence de l’oxydation du TiN pendant le dépôt diélectrique a pu être mise en évidence et caractérisée électriquement. Cette étude a amené à l’intégration d’un matériau supplémentaire jouant le rôle de barrière aux interfaces, produisant des condensateurs avec une durée de vie supérieure à 10ans dans les conditions d’utilisation viséesEnergy storage in embedded systems is still the subject of major R&D efforts as it requires a constant decrease in the volume of electronic components. It appears that the size of the discrete components, such as capacitors, is one of the brakes to the miniaturization of the final devices. Although technologies mainly based on silicon deep etching at the micrometric scale have made considerable progresses, they are now limited in terms of integration density. As a result, Murata IPS is developing a new 3D technology enabling a higher developed surface area. The use of such a matrix requires a MIM stack deposition technique such as ALD which is adapted to high aspect ratios. The aim of this thesis has been thus to integrate the MIM structure into the new 3D matrix while respecting the constraints inherent to the industry in order to give rise to the fifth generation of PICS™ technologies. The first challenge has been the achievement of sufficient step coverage of the films with an industrial equipment. A capacitance density greater than 1µF/mm² using a 10nm alumina film has been demonstrated. It also turns out that the TiN electrodes integration plays an important role on the 3D structure. Indeed, the mechanical stress had to be reduced to ensure the mechanical robustness of the structure, in particular by playing on the NH3 pulse. The metal-dielectric interfaces have also been the subject of an in-depth study where the influence of TiN oxidation during dielectric deposition has been shown and electrically characterized. This study has then led to the integration of an additional barrier material at the interfaces, producing capacitors with a 10-year lifetime under the intended voltage and temperature conditions
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Zhang, Yun. "MR playback characteristics and thermal stability of thin film media in high-density magnetic recording systems /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 1999. http://wwwlib.umi.com/cr/ucsd/fullcit?p9917958.
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Kumar, Manish. "High density and high reliability thin film embedded capacitors on organic and silicon substrates." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26655.
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Thesis (M.S.)--Materials Science and Engineering, Georgia Institute of Technology, 2009.Committee Chair: Tummala Rao; Committee Member: Pulugurtha Raj; Committee Member: Wong C P. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Hetel, Iulian Nicolae. "Quantum Critical Behavior In The Superfluid Density Of High-Temperature Superconducting Thin Films." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1204918571.
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Reck, James Nicholas. "Thin film techniques for the fabrication of nano-scale high energy density capacitors." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2008. http://scholarsmine.mst.edu/thesis/pdf/Reck_09007dcc805c0c2a.pdf.
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Thesis (Ph. D.)--Missouri University of Science and Technology, 2008.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed March 18, 2009) Includes bibliographical references.
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Yoshida, Yutaka, Yusuke Ichino, Masashi Miura, Yoshiaki Takai, Kaname Matsumoto, and Ataru Ichinose. "High critical current density in high field in Sm/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub 6+y/ thin films." IEEE, 2005. http://hdl.handle.net/2237/6776.
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Sethi, Kanika. "High-density capacitor array fabrication on silicon substrates." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37259.
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System integration and miniaturization demands are driving integrated thin film capacitor technologies with ultra-high capacitance densities for power supply integrity and efficient power management. The emerging need
for voltage conversion and noise-free power supply in bioelectronics and portable consumer products require ultra high-density capacitance of above 100 μF/cm2 with BDV 16-32 V ,independent capacitor array terminals and non-polar dielectrics. The aim of this research,therefore, is to explore a new silicon- compatible thin film nanoelectrode capacitor technology that
can meet all these demands. The nanoelectrode capacitor paradigm has two unique advances. The first advance is to achieve ultra-high surface area thin film electrodes by sintering metallic particles directly on a silicon substrate at CMOS- compatible temperatures. The second advance of this study is to conformally- deposit medium permittivity dielectrics over such particulate nanoelectrodes using Atomic Layer Deposition (ALD) process.
Thin film copper particle nanoelectrode with open-porous structure was achieved by choosing a suitable phosphate-ester dispersant, solvent and a
sacrificial polymer for partial sintering of copper particles to provide a continuous high surface area electrode. Capacitors with conformal ALD alumina as the dielectric and Polyethylene dioxythiophene (PEDT) as the top electrode showed 30X enhancement in capacitance density for a 20-30
micron copper particulate bottom electrode and 150X enhancement of capacitance density for a 75 micron electrode. These samples were tested
for their mechanical and electrical properties by using characterization techniques such as SEM, EDS, I-V and C-V plots. A capacitance density of
30 μF/cm2 was demonstrated using this approach.
The technology is extensible to much higher capacitance densities with better porosity control, reduction in particle size and higher
permittivity dielectrics.
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Atkinson, Lewis. "LLB micromagnetic models of nano-granular magnetic thin films for ultra-high density recording media." Thesis, University of York, 2016. http://etheses.whiterose.ac.uk/15588/.
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The continuing need for increased information storage capacity has driven a remarkable increase in areal density over the lifetime of hard disk technologies, built on the physical principles of nano magnetic structures. Understanding how the component nano-granular magnetic recording media operates at ultra-high densities and how novel switching mechanisms, such as heat assisted magnetic recording (HAMR), impact the nature of magnetic data storage is essential. In this thesis current state-of-the-art macro scale modeling methods, built on the principles of the Landau-Lifshitz-Bloch equation, are developed and applied to better understand the physical principles that govern the ultra-high density recording media. The modeling method is shown to be in close agreement with experiment in a number of situations. The dependence of magnetic damping, the combination of intrinsic and extrinsic damping, due to inter-granular interaction is shown to be significant. The form of the damping arises due to a change in the degeneracy of the ferromagnetic frequency of spinwaves, as a function of both increasing magnetostatic and inter-granular exchange interactions. The observed damping results in a nontrivial dependence of the magnetic switching time on intergranular interactions, within the range for the intergranular exchange and saturation magnetisation that is likely in ultra-high density recording media. The nontrivial nature of the switching time should be taken in to consideration when selecting materials for the magnetic grains and inter-granular regions. A detailed investigation of the HAMR process is made, concentrating on the thermodynamic limits of the technology. The nature of HAMR is shown to be far more complex than simply magnetisation reversal over a thermally reduced energy barrier. It is shown that, to achieve the required level of magnetisation reversal a number of factors must be considered. The temperature rise must be to the Curie point or above, invoking the linear reversal mechanism, with a cooling rate that is sufficiently low to allow the temperature of the media to remain higher than the blocking temperature for a period of time significantly larger than the relaxation time of the material. Also, the write field must be sufficiently large not only to reverse the magnetisation, but also to ensure no thermally activated back switching of the magnetisation, as in the concept of thermal writability. Also a new method for approximating the magnetostatic field to a high level of accuracy with a computational runtime that is comparable with the tensor form of the dipole approximation has been developed and tested.
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Liu, Haitao. "Novel 3-D CMOS and BiCMOS devices for high-density and high-speed ICs /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202003%20LIU.
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Lee, Jong-Heon. "Preparation of high density particulate preforms and their consolidation by the thermal gradient-forced flow diamond CVI process." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/32811.
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Joyce, Donna Marie. "The Development of DNA-Based Bio-Polymer Hybrid Thin Films for Capacitor Applications." University of Dayton / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1389285491.
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He, Yafei, Panpan Zhang, Faxing Wang, Luxin Wang, Yuezeng Su, Fan Zhang, Xiaodong Zhuang, and Xinliang Feng. "Vacancy modification of Prussian-blue nano-thin films for high energy-density microsupercapacitors with ultralow RC time constant." Elsevier, 2019. https://tud.qucosa.de/id/qucosa%3A73173.
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In-plane micro-supercapacitors (MSCs), as promising power candidates for micro-devices, typically exhibit high power densities, large charge/discharge rates, and long cycling lifetimes. The high areal/volumetric capacitances, high energy/power densities, high rate capability, as well as flexibility are the main scientific pursue in recent years. Among diverse electrode materials for MSCs, coordination polymer frameworks are emerging due to the designable porous structure and tunable functionality. However, the unsatisfied electrochemical performance still hinders their practical applications. In this work, we demonstrate the first time an efficient in-situ growth approach to precisely modify the vacancy of Prussian-blue nano-thin films with pyridine by coordination reaction for high energy-density MSCs. Confirmed by the experimental results and density functional theory calculation, the vacancy modification within Prussian-blue network improved the film-forming property, hydrophilicity, and electrochemical activity of the thin films. The resultant MSCs based on pyridine-modified Prussian-blue exhibited an ultrahigh energy density of up to 12.1 mWh cm⁻³ and an ultra-low time constant (t₀) of 0.038 ms, which are the best values among the state-of-the-art in-plane MSCs. This work provides an attractive solution for structural engineering of promising active materials on molecule level toward high-performance micro-energy devices.
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Wallin, Erik. "Alumina Thin Films : From Computer Calculations to Cutting Tools." Doctoral thesis, Linköpings universitet, Plasma och beläggningsfysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15360.
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The work presented in this thesis deals with experimental and theoretical studies related to alumina thin films. Alumina, Al2O3, is a polymorphic material utilized in a variety of applications, e.g., in the form of thin films. However, controlling thin film growth of this material, in particular at low substrate temperatures, is not straightforward. The aim of this work is to increase the understanding of the basic mechanisms governing alumina growth and to investigate novel ways of synthesizing alumina coatings. The thesis can be divided into two main parts, where the first part deals with fundamental studies of mechanisms affecting alumina growth and the second part with more application-oriented studies of high power impulse magnetron sputter (HiPIMS) deposition of the material. In the first part, it was shown that the thermodynamically stable α phase, which normally is synthesized at substrate temperatures of around 1000 °C, can be grown using reactive sputtering at a substrate temperature of merely 500 °C by controlling the nucleation surface. This was done by predepositing a Cr2O3 nucleation layer. Moreover, it was found that an additional requirement for the formation of the α phase is that the depositions are carried out at low enough total pressure and high enough oxygen partial pressure. Based on these observations, it was concluded that energetic bombardment, plausibly originating from energetic oxygen, is necessary for the formation of α-alumina (in addition to the effect of the chromia nucleation layer). Moreover, the effects of residual water on the growth of crystalline films were investigated by varying the partial pressure of water in the ultra high vacuum (UHV) chamber. Films deposited onto chromia nucleation layers exhibited a columnar structure and consisted of crystalline α-alumina if deposited under UHV conditions. However, as water to a partial pressure of 1*10-5 Torr was introduced, the columnar α-alumina growth was disrupted. Instead, a microstructure consisting of small, equiaxed grains was formed, and the γ-alumina content was found to increase with increasing film thickness. To gain a better understanding of the atomistic processes occurring on the surface, density functional theory based computational studies of adsorption and diffusion of Al, O, AlO, and O2 on different α-alumina (0001) surfaces were also performed. The results give possible reasons for the difficulties in growing the α phase at low temperatures through the identification of several metastable adsorption sites and also show how adsorbed hydrogen might inhibit further growth of α-alumina crystallites. In addition, it was shown that the Al surface diffusion activation energies are unexpectedly low, suggesting that limited surface diffusivity is not the main obstacle for low-temperature α-alumina growth. Instead, it is suggested to be more important to find ways of reducing the amount of impurities, especially hydrogen, in the process and to facilitate α-alumina nucleation when designing new processes for low-temperature deposition of α-alumina. In the second part of the thesis, reactive HiPIMS deposition of alumina was studied. In HiPIMS, a high-density plasma is created by applying very high power to the sputtering magnetron at a low duty cycle. It was found, both from experiments and modeling, that the use of HiPIMS drastically influences the characteristics of the reactive sputtering process, causing reduced target poisoning and thereby reduced or eliminated hysteresis effects and relatively high deposition rates of stoichiometric alumina films. This is not only of importance for alumina growth, but for reactive sputter deposition in general, where hysteresis effects and loss of deposition rate pose a substantial problem. Moreover, it was found that the energetic and ionized deposition flux in the HiPIMS discharge can be used to lower the deposition temperature of α-alumina. Coatings predominantly consisting of the α phase were grown at temperatures as low as 650 °C directly onto cemented carbide substrates without the use of nucleation layers. Such coatings were also deposited onto cutting inserts and were tested in a steel turning application. The coatings were found to increase the crater wear resistance compared to a benchmark TiAlN coating, and the process consequently shows great potential for further development towards industrial applications.
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Tewg, Jun-Yen. "Zirconium-doped tantalum oxide high-k gate dielectric films." Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/1346.
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A new high-k dielectric material, i.e., zirconium-doped tantalum oxide (Zr-doped TaOx), in the form of a sputter-deposited thin film with a thickness range of 5-100 nm, has been studied. Important applications of this new dielectric material include the gate dielectric layer for the next generation metal-oxide-semiconductor field effect transistor (MOSFET). Due to the aggressive device scaling in ultra-large-scale integrated circuitry (ULSI), the ultra-thin conventional gate oxide (SiO2) is unacceptable for many practical reasons. By replacing the SiO2 layer with a high dielectric constant material (high-k), many of the problems can be solved. In this study, a novel high-k dielectric thin film, i.e., TaOx doped with Zr, was deposited and studied. The films electrical, chemical, and structural properties were investigated experimentally. The Zr dopant concentration and the thermal treatment condition were studied with respect to gas composition, pressure, temperature, and annealing time. Interface layer formation and properties were studied with or without an inserted thin tantalum nitride (TaNx) layer. The gate electrode material influence on the dielectric properties was also investigated. Four types of gate materials, i.e., aluminum (Al), molybdenum (Mo), molybdenum nitride (MoN), and tungsten nitride (WN), were used in this study. The films were analyzed with ESCA, XRD, SIMS, and TEM. Films were made into MOS capacitors and characterized using I-V and C-V curves. Many promising results were obtained using this kind of high-k film. It is potentially applicable to future MOS devices.
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Nguyen, Van-Son. "Films minces et dispositifs à base de LixCoO₂ pour application potentielle aux mémoires résistives non volatiles." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS344/document.
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La mémoire Flash est actuellement extrêmement utilisée en tant que mémoire non volatile pour le stockage des données numériques dans presque tout type d'appareil électronique nomade (ordinateur portable, téléphone mobile, tablette, …). Pour dépasser ses limites actuelles (densité d'informations, endurance, rapidité), un grand nombre de recherches se développent notamment autour du concept de mémoires résistives qui repose sur la commutation entre différents niveaux de résistance, via l'application d'une tension.Les mémoires dont la variation de résistance dépend de réactions électrochimiques (ReRAM) sont potentiellement de bonnes candidates pour les mémoires non volatiles de prochaine génération; les mécanismes d'oxydo-réduction impliqués sont cependant souvent de type filamentaire, mettant notamment en jeu des migrations de cations d’éléments métalliques (provenant des électrodes), ou de lacunes d’oxygène. Ce caractère filamentaire rend difficilement atteignable la miniaturisation extrême, à l’échelle nanométrique.Dans cette thèse, une classe de matériaux particulière -utilisée dans le domaine du stockage d'énergie- est étudiée. L’objectif est d’approfondir l’origine des processus de commutation de résistance observés sur des films de LixCoO2. Nous caractérisons d'abord les propriétés structurales et électriques de tels films, ainsi que le comportement électrique des dispositifs élaborés à partir de ces films. Nous étudions ensuite les mécanismes électrochimiques qui sont à l’origine des commutations résistives, dans la configuration d’un contact micrométrique électrode/film/électrode. Nous cherchons à déterminer la validité d’un mécanisme qui avait été proposé auparavant, mais non démontré. Nous étudions également la cinétique de commutation des dispositifs, et proposons un modèle numérique permettant d’expliquer les résultats expérimentaux observés. Enfin, nous étudions l’applicabilité potentielle des dispositifs (intégrant les films de LixCoO2) aux mémoires Re-RAM au travers de leurs performances en termes d’endurance (nombre maximum de cycles d’écriture/effaçage), et de stabilité. En particulier, nous étudions l’influence de plusieurs paramètres (impulsions de tension, nature des électrodes, température et c…) sur ces performancesFlash memory is now extensively used as non-volatile memory for digital data storage in most mobile electronic devices (laptop, mobile phone, tablet...). To overcome its current limits (e.g. low information density, low endurance and slow speed), many researches recently developed around the concept of resistive memories based on the switching between different resistance levels by applying appropriate bias voltages.Memories whose resistance variations depend on electrochemical reactions (ReRAM) are potentially good candidates towards next-generation non-volatile memories. The underlying redox mechanisms observed are however often of the filamentary type, involving in particular migration of cations of metal elements (coming from the electrodes), or oxygen vacancies. This filamentary character makes it challenging to attain extreme downscaling towards the nanometric scale.In this thesis, a particular class of materials - used in the field of energy storage - is studied. The aim is to investigate the origin of the resistance switching processes observed in LixCoO2 films. We first characterize the structural and electrical properties of such films, as well as the electrical behaviors of the devices elaborated therefrom. We then investigate the electrochemical mechanisms which are at the origin of resistive switching, in the micrometric electrode/film/electrode configuration. We try to determine the validity of a formerly proposed mechanism which was however not yet demonstrated. Furthermore, we study the experimental switching kinetics of devices, and propose a numerical model to explain the results observed. Finally, we examine the potential applicability of LixCoO2-based devices to Re-RAM memories through the study of their performances in terms of endurance (i.e. maximum number of write/erase cycles) and retention. Specifically, the influence of several parameters (such as voltage pulses, chemical nature of the electrodes, temperature etc.) on these performances is investigated
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Wollesen, Laura. "Nouveaux films minces scintillants ultra-denses et solutions alternatives pixélisées pour l'imagerie synchrotron par rayon X." Electronic Thesis or Diss., Lyon 1, 2023. https://n2t.net/ark:/47881/m60k28pm.
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Deux approches ont été employées pour développer des scintillateurs couche mince à haut pouvoir d’arrêt. Ceux-ci sont utilisés pour l'imagerie à rayons X à haute résolution spatiale dans les synchrotrons. • La première approche a consisté à faire croître par Epitaxie en Phase Liquide (EPL) des films monocristallins (SCF) à densité et nombre atomique effectif (Z) élevés. L'objectif est ainsi d'atteindre une résolution spatiale élevée, tout en maximisant l'efficacité d'absorption au rayons X des films. Avant de mettre au point les procédures d'épitaxie en phase liquide, les composés potentiels ont été étudiés à l'aide d'un outil de simulation Monte Carlo (Geant4), combiné à des calculs analytiques, afin d'évaluer leur résolution spatiale intrinsèque ainsi que leur efficacité d’absorption aux rayons X. A la suite de cette étude, différentes couches épitaxiées basées sur les hafnates ont été mises au point sur des substrats de ZrO2 :Y. Plus particulièrement, le Lu2Hf2O7 a été développé avec succès. Les structures atomiques des films se sont confirmées comme étant iso-structurelles par rapport au substrat et présentant un faible désaccord paramétrique cristallin. Il a été constaté que divers éléments pouvaient entrer facilement dans la structure, révélant ainsi une flexibilité surprenante du système hafnate pour la croissance LPE. Par ailleurs les films de Lu2Hf2O7 dopés à l'europium présentent une luminescence caractéristique de l’ion Eu3+. Le substrat de ZrO2 :Y quant à lui présente une émission de faible intensité, du fait de la présence de défauts de vacances en oxygène. Les films ont un rendement lumineux plutôt faible mais offrent une bonne réponse spatiale, validée par les mesures de Fonction de Transfert de Modulation (MTF) ainsi que par des radiographies et tomographies rayon X réalisées sur ces échantillons.• La deuxième approche a consisté à faire croître des scintillateurs SCF de manière micro-structurée par EPL. L'objectif est ainsi de pouvoir augmenter le pouvoir d’arrêt des scintillateurs tout en conservant une bonne résolution spatiale. Dans un premier temps des substrats de GGG et de LYSO :Ce ont subis un traitement laser ultra-rapide (ps), permettant de modifier la surface de ces substrats, et ce afin de réduire le taux de croissance LPE dans les zones ainsi altérées. Ensuite, la croissance de scintillateurs LSO :Tb et GGG :Eu a été réalisée sur ces substrats respectifs de LYSO :Ce et GGG, mettant en évidence la croissance de ‘’piliers’’, résultant en une surface micro-structurée. La morphologie des ‘’piliers’’ varie en fonction du composé et de l'orientation du substrat. Les structures atomiques et les propriétés luminescentes sont comparables à celles de leurs homologues SCF non micro- structurés. Une preuve de concept a ainsi été démontréeThe development of scintillators with high stopping power for high spatial resolution X-ray imaging at synchrotrons has been performed by employing two approaches. The first approach was to grow thin Single Crystalline Films (SCFs) of high density and effective Z number by Liquid Phase Epitaxy (LPE). This is to reach ultimate high spatial resolution while maximizing the absorption efficiency of the films. Before attempting to develop the LPE procedures, the compounds were investigated with a Geant4, Monte Carlo simulation tool combined with subsequent analytical calculations to evaluate their scintillating spatial response. Ultimate high-density compound, Lu2Hf2O7, and other hafnates have in this framework been successfully grown on ZrO2:Y substrates. The atomic structures of the films were confirmed to be iso-structural with the substrate and have a low lattice mismatch. It was experienced that various elements could enter the structure, and a surprising flexibility of the hafnate system for LPE growth is thereby realized. The grown films of Lu2Hf2O7 doped with Europium are discovered to scintillate. However, the substrate itself displays low-intensity emission. The films have a rather low light output but deliver a good spatial response validated by MTFs as well as when performing radiography and tomography. The second approach was to grow state-of-the-art SCF scintillators in a micro-structured manner by LPE. The aim is to increase the stopping power by having tall pillars containing light and maintaining a good spatial response. LSO:Tb and GGG:Eu, were grown micro-structured onto laser-treated LYSO:Ce and GGG substrates, respectively. The morphology of the pillars varies depending on the compound and the substrate orientation. The atomic structures and luminescent properties are comparable to their normal SCF counterparts. Thereby a proof of concept has been demonstrated
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Kurth, Fritz. "High Magnetic Field Properties of Fe-pnictide Thin Films." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-189964.
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The recent discovery of high-temperature superconductivity in Fe-based materials triggered worldwide efforts to investigate their fundamental properties. Despite a lot of similarities to cuprates and MgB2, important differences like near isotropic behaviour in contrast to cuprates and the peculiar pairing symmetry of the order parameter (OP) have been reported. The OP symmetry of Fe-based superconductors (FBS) was theoretically predicted to be of so-called s± state prior to various experimental works. Still, most of the experimental results favour the s± scenario; however, definitive evidence has not yet been reported. Although no clear understanding of the superconducting mechanisms yet exists, potential applications such as high-field magnets and Josephson devices have been explored. Indeed, a lot of reports about FBS tapes, wires, and even SQUIDs have been published to this date. In this thesis, the feasibility of high-field magnet applications of FBS is addressed by studying their transport properties, involving doped BaFe2As2 (Ba-122) and LnFeAs(O,F) [Ln=Sm and Nd]. Particularly, it is important to study physical properties in a sample form (i.e. thin films) that is close to the conditions found in applications. However, the realisation of epitaxial FBS thin films is not an easy undertaking. Recent success in growing epitaxial FBS thin films opens a new avenue to delve into transport critical current measurements. The information obtained through this research will be useful for exploring high-field magnet applications. This thesis consists of 7 chapters: Chapter 1 describes the motivation of this study, the basic background of superconductivity, and a brief summary of the thin film growth of FBS. Chapter 2 describes experimental methods employed in this study. Chapter 3 reports on the fabrication of Co-doped Ba-122 thin films on various substrates. Particular emphasis lies on the discovery of fluoride substrates to be beneficial for epitaxy without compromising superconducting properties. It is worth mentioning, that a world record Tc of 28 K for Co-doped Ba-122 thin films is reported here. Chapter 4 describes high-field transport properties (up to dc 35 T) of epitaxial P-doped Ba-122 thin films prepared by MBE. Among the FBS, P-doped Ba-122 shows very high transport critical current densities, although the Tc is lower than for LnFeAs(O,F)[Ln=Sm and Nd]. Additionally, the film is microstructurally clean. These high Jc values are due to a high vortex line energy. Chapter 5 deals with transport properties of epitaxial SmFeAs(O,F) thin films. In the course of this work, a dc 45 T magnet has been used within collaboration with the National High Magnetic Field Laboratory at Tallahassee, FL, USA. SmFeAs(O,F) thin films have been prepared by molecular beam epitaxy (MBE). The investigated film shows a very high transport critical current density (Jc) of over 105 A/cm2 at 45T and 4.2K for both main crystallographic directions, which features favourable for high-field magnet applications. Additionally, by investigating the pinning properties, a dimensional crossover between the superconducting coherence length and the FeAs interlayer distance at 30-40K was observed. Chapter 6 reports on high-field transport properties of NdFeAs(O,F) thin films prepared by MBE. In this case, the transition from Abrikosov to Josephson vortices was observed around 20-30K. Additionally, the angular Jc data were scaled with the anisotropic GinzburgLandau approach. The obtained parameters at given temperature are observed to increase with decreasing temperature, which is different from Co-doped Ba-122. Chapter 7 summarises this workDie kürzliche Entdeckung von Hochtemperatur-Supraleitung in Fe-basierten Materialien löste weltweite Bemühungen aus, deren grundlegende Eigenschaften zu untersuchen. Neben vielen Gemeinsamkeiten mit den Kupraten und MgB2 sind wichtige Unterschiede wie nahezu isotropes Verhalten (im Gegensatz zu den Kupraten) und eine auffällige Paarungssymmetrie des Ordnungsparameters (OP) berichtet worden. Die OP-Symmetrie der Fe-basierten Supraleiter (FBS) wurde theoretisch als s± berechnet, noch bevor experimentelle Versuche unternommen wurden. Derzeit favorisieren experimentelle Ergebnisse das s±-Szenario, dennoch gibt es noch keine definitiven Nachweise. Obwohl noch kein komplettes Verständnis des supraleitenden Mechanismus existiert, wurden schon potentielle Anwendungen wie Josephson-Elemente und Hochfeldmagnete erforscht. In der Tat erschienen zahlreiche Veröffentlichungen über supraleitende Kabel, Bänder und auch SQUIDs. Diese Arbeit befasst sich mit der Durchführbarkeit von Hochfeld-Anwendungen durch die Untersuchung der Transporteigenschaften von FBS, namentlich Ba-122 und LnFeAs(O,F)[Ln=Sm und Nd]. Es ist von großer Wichtigkeit, die physikalischen Eigenschaften in einer Probenform zu untersuchen, die der Form in Anwendungen nahekommt (z.B. Dünnschichten), um dieselben Rahmenbedingungen vorgeben zu können. Es ist jedoch nicht einfach, epitaktische FBS Dünnschichten zu realisieren. Kürzlich gewonnene Erkenntnisse in der Herstellung von epitaktischen FBS-Dünnschichten ermöglichen nun ein tieferes Eindringen in die Transporteigenschaften. Die in diesen Untersuchungen gewonnenen Informationen stellen somit wichtige Argumente in der Diskussion um Hochfeld Anwendungen dar. Diese Arbeit besteht aus sieben Kapiteln: Kapitel 1 beinhaltet die Motivation dieser Arbeit, die Grundlagen der Supraleitung und eine kurze Zusammenstellung der bisherigen Arbeiten zur Dünnschichtherstellung von FBS. Kapitel 2 beschreibt experimentelle Methoden, die im Zuge dieser Arbeit verwendet wurden. Kapitel 3 berichtet von der Herstellung Co-dotierter Ba-122 Dünnschichten (Co-Ba-122) auf verschiedenen Fluoridsubstraten. Dabei wurde Augenmerk darauf gelegt, neben einem verbesserten epitaktischen Wachstum der Dünnschichten die supraleitenden Eigenschaften nicht zu beeinträchtigen. Anzumerken ist, dass in diesem Rahmen Tc-Rekord-Werte von 28 K in Co-Ba-122 erzielt werden konnten. Kapitel 4 beschreibt die Hochfeld-Transporteigenschaften epitaktisch gewachsener P-dotierter Ba-122 Dünnschichten, die durch MBE hergestellt wurden. Unter den FBS zeigt P-dotiertes Ba-122 enorm hohe kritische Transport-Stromdichten, obwohl das Tc niedriger ist als bei LnFeAs(O,F)[Ln=Sm und Nd]. Der Grund dafür konnte in der hohen Flusslinienkern-Energie des P-dotierten Ba-122 ermittelt werden. Kapitel 5 behandelt Transporteigenschaften von epitaktisch gewachsenen SmFeAs(O,F)-Dünnschichten. In diesem Zusammenhang wurde ein dc-45 T-Hochfeldmagnet in Zusammenarbeit mit dem National High Magnetic Field Laboratory in Tallahassee, Florida, USA, genutzt. SmFeAs(O,F)-Dünnschichten wurden mit dem Molekularstrahl-Verfahren (MBE) hergestellt. Die Schichten zeigen sehr hohe kritische Transport-Stromdichten (Jc) von über 105 A/cm2 bei 45 T und 4.2 K für beide kristallographische Hauptrichtungen, parallel zur c-Achse und in der ab-Ebene. Diese Ergebnisse sehen sehr verheißungsvoll für eine Verwendung in Hochfeld-Anwendungen aus. Zusätzlich konnte durch die Untersuchung der Pinning-Eigenschaften ein Dimensionsübergang zwischen supraleitender Kohärenzlänge und FeAs-Ebenenabstand im Bereich 30-40 K beobachtet werden. Kapitel 6 berichtet über die Hochfeld-Transporteigenschaften von NdFeAs(O,F)-Dünnschichten, die mithilfe des MBE-Verfahrens hergestellt wurden. In diesem Falle konnte ein Ubergang von Abrikosov- zu Josephson-Flusslinien im Temperaturbereich 20-30 K beobachtet werden. Zusätzlich konnte die winkelabhängige kritische Stromdichte mit dem anisotropen Ginzburg-Landau-Ansatz skaliert werden. Die erhaltenen Parameter für verschiedene Temperaturen steigen mit fallender Temperatur. Dieses Verhalten ist gegensätzlich zu dem in Co-dotiertem Ba-122 gefundenen. Kapitel 7 gibt eine Zusammenfassung dieser Arbeit
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Tirumala, Sridhar. "Integration of Ferroelectric Materials into High Density Non-Volatile Random Access Memories." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/28800.
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The characteristic polarization response of a ferroelectric material to an applied electric field enables a binary state device in the form of a thin film ferroelectric capacitor that can be used to store digital information. In a high density memory the capacitor is placed on the top of a poly-silicon plug which is connected to the drain of a transistor. Such a configuration poses constraints on the processing conditions of the ferroelectric capacitor in addition to the already existing reliability issues of a ferroelectric capacitor. The current research is an attempt to integrate the ferroelectric capacitor directly into a high density memory structure.
Pb1.1Zr0.53Ti0.47O₃ (PZT) and SrBi₂Ta₂O₉ (SBT) are two most promising materials for ferroelectric memory applications. PZT has excellent ferroelectric properties with wide operating temperature range. However, PZT exhibits a considerable loss of switchable polarization with cumulative switching cycles. This phenomenon is known as fatigue and is one of the critical problems affecting the life time of ferroelectric memories. In this research, Ir based electrodes are shown to improve fatigue characteristics of PZT based capacitors not only by enhancing a homogenous growth of perovskite phase of PZT but also by lowering the entrapment of oxygen vacancies at the interface. These Ir electrodes also acted as diffusion barriers for silicon, oxygen and lead. Additionally, Ir electrodes were found to be chemically stable at the processing temperatures of PZT capacitors. These features of Ir based electrodes could help in realization of a practical PZT based high density non volatile random access memories. SBT is an another promising ferroelectric material for ferroelectric memory applications. While SBT has a fatigue free nature, it has a very high processing temperature (>800 °C). Such a high processing temperature limits the choice of electrodes that could be used to integrate the ferroelectric capacitor into the high density memory structure. In this research, an attempt is made to lower the processing temperature and suitable electrodes are chosen accordingly, to enable the integration of SBT based capacitors into high density memories. Lowering the processing temperature was obtained by growing a-b oriented SBT crystallites rather than c-axis oriented crystallites. Additionally, reliability (degradation) and yield of SBT thin film capacitors was found to be correlated to the amount of segregated bismuth oxide in the films. Elimination of secondary phase bismuth oxide was found to result in dramatic improvement in the reproducibility of SBT thin films with a processing temperature close to 750 °C.
PtRh based electrodes were found to be quite suitable for integrating SBT capacitors into high density memory structures. These electrodes could withstand a processing temperature of 750 °C while preventing the interdiffusion of silicon, oxygen and bismuth. A solid solution of SBT and Bi₃TiNbO₉ (BTN) is made which reduced the processing temperature of the capacitor material from 750 °C to 650 °C while retaining the excellent fatigue and retention characteristics of SBT.Ph. D.
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Wang, Yushu. "Thin-film trench capacitors for silicon and organic packages." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42741.
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The continuous trend towards mega-functional, high-performance and ultra-miniaturized system has been driving the need for advances in novel materials with superior properties leading to thin components, high-density interconnect substrates and interconnections. Power supply and management is becoming a critical bottleneck for the advances in such mega-functional systems because power components do not scale down with the rest of the system resulting in bulky and stand-alone power modules. Amongst the power components, thin film capacitors are considered the most challenging to integrate because of several manufacturability concerns. The challenges are related to process compatibility of high permittivity dielectrics with substrates and high surface area electrodes, yield, leakage and losses. This thesis focuses on novel thin film capacitor technologies that address some of these critical challenges.Thesis advisor has approved the addition of errata to this item. The abstract text in the metadata record has been modified to match the document text.
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Sebastian, Mary Ann Patricia. "Enhancing the Flux Pinning of High Temperature Superconducting Yttrium Barium Copper Oxide Thin Films." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1501777042774346.
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Tada, Yasuhiko. "Morphology and Placement Control of Microdomain Structure in Block Copolymer Thin Film for Fabricating Ultra High Density Pattern." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157615.
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González, Oyarce Aníbal Lautaro. "360° domain walls : nucleation mechanisms during thin film switching, and their application to high density non-volatile memory." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708186.
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Gueye, Ibrahima. "Optimization of physical chemistry of the Pt/Ru/PbZrTiO3 interface for future high capacitance density devices." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT119/document.
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Le besoin croissant d'intégration de nouvelles fonctions dans les futures générations de dispositifs portables contribue au surpeuplement des circuits imprimés. Dans ce contexte, la miniaturisation des composants discrets est impérative pour compenser l'augmentation de leur nombre et pour garder la taille des cartes de circuit imprimé gérable. L'un des composants les plus courants de ce type est le condensateur, qui peut être utilisé pour découpler une partie d'un réseau électrique d'un autre. Cependant, la miniaturisation des condensateurs nécessite une augmentation de leur densité de capacité, impliquant l'intégration de condensateurs haute densité. Le succès d'une telle intégration repose sur l'utilisation à la fois de matériaux à haute constante diélectrique et d'une architecture d'empilement. Dans ce contexte, les couches de titanate-zirconate de plomb (PZT) combinées aux piles multi-MIM sont de bons candidats pour la nouvelle génération de condensateurs. La technologie multi-MIM consiste à empiler deux ou plusieurs structures MIM en parallèle afin d'augmenter la densité de la capacité sans modification effective de la surface. Avec la géométrie multi-MIM, la performance de l'appareil est fortement affectée par la qualité de l'interface Métal/PZT, il est donc important d'élaborer une chimie d'interface qui ne dégrade pas les performances des multi-MIM.Cette thèse soutenue par le projet français «Programme de l'économie numérique des investissements d'Avenir » vise deux axes de développement pour l’améliorer de la qualité des interfaces Pt/Ru/PZT: la première concerne l'optimisation du contenu de Pb en excès dans la couche de PZT, tandis que le second étudie les effets du recuit de post métallisation (PMA).La première partie de la thèse est dédiée aux analyses de densité de capacité réalisées sur les condensateurs Pt/Ru/PZT/Pt en fonction de l'excès de précurseur du Pb dans les couches de PZT déposées par voie sol-gel (10, 15, 20 et 30% de Pb respectivement pour PZT10, PZT15, PZT20 et PZT30).Nous montrons qu'une augmentation de l'excès de Pb de 10 à 20% entraîne une augmentation de la constante diélectrique maximale (environ 8,8%), ainsi qu'une diminution de la tangente de perte (de 4,36 à 3,08%) et du champ de claquage (de 1,68 à 1,26MV/cm). La PMA favorise l'augmentation du maximum de constant diélectrique (jusqu'à 7,5%) et le champ de claquage augmente de 0.5 MV/cm.Ensuite, l'influence de la chimie de surface des PZT est étudiée en fonction de l'excès de précurseur de Pb. Cet excès de Pb permet de compenser l'évaporation du plomb pendant le traitement thermique successif. En utilisant la spectroscopie de photoélectrons par rayons X (XPS), nous montrons la présence d'une phase de surface ZrOx. Les faibles niveaux d'excès de Pb conduisent à la formation de nanostructures ZrOx à la surface de la couche de PZT. Un taux plus élevé en Pb favorise la disparition totale nanostructures ZrOx en surface.Enfin, nous avons sondé l'interface Pt/Ru/PZT en fonction de l'excès de Pb et de la PMA. La microscopie électronique en transmission (TEM) montre que les nanostructures de ZrOx sont présentes à l'interface du Ru/PZT10. Les nanostructures cristallines ZrOx pourraient former une couche non ferroélectrique et ainsi affecter la densité de capacité. L'analyse en mode operando (sous polarisation in situ) par XPS haute-énergie montre une réponse électronique dépendant de la polarisation appliquée, probablement grâce à l’écrantage imparfait du champ dépolarisant à l'interface Pt/Ru/PZT10. En outre, une nouvelle phase (PbOx) est observée au niveau Pt/Ru/PZT30, probablement liée à la quantité de Pb en excès dans le PZT30. Cette phase semble induire la diminution du champ de claquage et la densité de capacité observée au niveau du Pt/Ru/PZT30/Pt. Enfin, PMA sur le Pt/Ru/PZT10 montre la création d'alliage à base de ZrRuOx et PbRuOx qui pourrait être à l'origine de l'amélioration des réponses électriques des condensateurs PZT après PMAThe growing need for the integration of an increasing number of functions into the new generation of portable devices contributes to overcrowding of printed circuit boards. In this context, the miniaturization of discrete components is imperative to maintain a manageable size of the printed circuit boards. Decoupling capacitors are one of the most important such discrete components. Miniaturization requires an increase of capacitance density, involving the integration of high-density capacitors. The success of such integration relies on the use of both high dielectric permittivity materials and a suitable stacking architecture. Lead zirconate titanate (PZT) in decoupling multiple metal-insulator-metal (multi-MIM) stacks is a good candidate for the new generation of integrated capacitors. The multi-MIM technology consists in stacking two or more PZT film-based MIM structures connected in parallel in order to increase the density of the capacitance without any effective surface area change. Device performance is heavily affected by the quality of the interface with the electrodes, so it is important to engineer interface chemistry which does not degrade the multi-MIM performance.This thesis, supported by the French “Programme de l’économie numérique des investissements d’Avenir” addresses two aspects of development aiming to improve the quality of the Pt/Ru/PZT interfaces: the first one concerns the optimization of Pb excess content in the PZT film, while the second one investigates the Post Metallization Annealing (PMA) done after deposition of electrode/PZT multilayer.The first part of the thesis presents the capacitance density analysis performed on Pt/Ru/PZT/Pt capacitors as a function of Pb excess in the sol-gel precursor solution (10, 15, 20 and 30% of excess Pb for PZT10, PZT15, PZT20 and PZT30, respectively). Pb excess compensates the lead evaporation during calcination.An increase of Pb excess from 10 to 20% leads to an increase of the maximum dielectric constant of 8.8%, a decrease of the loss tangent from 4.36 to 3.08% and breakdown field from 1.68 to 1.26MV/cm. PMA favors the enhancement of the maximum of dielectric constant by 7.5%, and the breakdown field increases to 0.5 MV/cm.The influence of the surface chemistry is studied as a function of Pb precursor excess. X-ray photoelectron spectroscopy (XPS) demonstrates that low level of Pb excess leads to the presence of a ZrOx surface phase in the form of nanostructures. Higher Pb precursor content allows the PZT synthesis to proceed to its end-point, fully consuming the ZrO2 precursor and eliminating the low dielectric constant ZrOx surface phase.We have then studied the Pt/Ru/PZT interface as a function of Pb excess and PMA. Transmission Electron Microscopy (TEM) cross-sectional analysis shows that the crystalline ZrOx nanostructures are still present at the electrode interface, constituting a dielectric layer which contributes to defining capacitor performance. Operando (under bias in situ) hard X-ray photoelectron spectroscopy (HAXPES) analysis using synchrotron radiation highlights an electronic response dependent on the applied polarization, most probably due to imperfect screening of the depolarizing field at the Pt/Ru/PZT10 interface. Furthermore, a new phase (PbOx) is observed at the Pt/Ru/PZT30 due to the high Pb excess. This new phase seems to induce a reduction in breakdown field and capacitance density. Finally, PMA on the Pt/Ru/PZT10 suggests the creation of interface ZrRuOx and PbRuOx which could be at the origin of the improvement of electrical responses of PZT capacitors after PMA.In conclusion, this thesis has provided valuable information and methodology on the correlation between surface and interface physical chemistry of PZT and Pt/Ru/PZT and electric characteristics of PZT based MIM capacitors
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Celestina, Richard A. "Development of New Single and High-Density Heat Flux Gauges for Unsteady Heat Transfer Measurements in a Rotating Transonic Turbine." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1608551902273547.
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HSU, CHENG-MING, and 許正明. "Characteristics of High Density Vertical Lanthanum Nanowire Heterostructure GZO Thin Films." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/dt9673.
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碩士南臺科技大學
電子工程系
106
In this study, silicon nanowires (SiNW) were fabricated through metal-assisted chemical etching (MACE) using silicon wafers as the substrate. The etching time parameters were changed, and different lengths of nanowires were produced using the following parameters: not etched, etched for 10 minutes, 30 minutes, and 60 minutes respectively. Afterwards, a GZO film was prepared by means of RF magnetron sputtering on a wafer with a nanostructure. A positive and a negative electrode were formed from an aluminum ingot using a thermal evaporator. Then, the effect on the GZO film was studied after changing the process parameters. For the microstructure analysis, a Field Emission Scanning Electron Microscope (FE-SEM) was used to observe the structure of the surface and the cross-section of the film, as well as to measure the thickness of the film and the length of the nanowire. X-Ray Diffraction (XRD) was used to identify the crystal phase of the GZO film. Then, the carrier concentration, carrier mobility, and resistivity were measured through the Hall Effect Analyzer. Finally, by measuring the I-V characteristics, the best parameters in the experiment were obtained. As a result, the experimental results show that best etching time of SiNW was 30 minutes.
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Lin, Sung-Che, and 林頌哲. "Spin-on Phosphorous Dopant for Super-High Density Silicon Quantum Dot Thin Films." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/77s3x2.
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碩士國立交通大學
光電工程研究所
105
Recently, nanocrystalline silicon quantum dot (nc-Si QD) thin films are widely used in the solar cells (SCs). The high-tunable ability of energy bandgap (Eg) is regarded as a feasible method to break through the highest theoretical conversion efficiency of the single Eg. In order to increase the QD density or reduce the separation between QD for enhancement of carrier tunneling probability, the super-high Si QD thin films gradient Si-rich oxide multi-layer (GSRO-ML) has been demonstrated in our previous work. To further enhance the film electrical properties, the main purpose is increasing the current density and conductivity by impurity (B or P atoms) doping and activation. In 2014, the POCl3 process of thermal diffusion was carried out for P atoms doped in GSRO-ML structure. The photoelectric properties have significantly improved but the decline in fill factor (F.F.) limits the PV’s conversion efficiency. The main propose of this study focuses on changing the doping method. The “pre-deposition” is carried out by spin-on process that using the phosphor-doped P2O5. After spin-on, P atoms are activated into the GSRO-ML structure in thermal diffusion furnace. With P atom doping, optoelectronic properties are clearly enhanced but also the defeats repaired that the fill factor is effectively increased. Under P-doping, the crystallinity and high absorption coefficient are well-maintained. The electrical and PV properties are enhanced and lead to the optimized performances with increasing P2O5 dopant concentration. At higher concentrations, surplus P atoms accumulate between the interface of Si QD and SiO2 matrix that carrier mobility significantly reduced and results in poorer conversion efficiency. Under the optimized doping conditions, changing the diffusion temperature and time to find out more effective activation parameters and achieve the best conversion efficiency in this study. In addition, when the thickness of GSRO-ML structure and the doping amount of P atoms increase, the photoelectric properties of cells are obviously improved which has a great potential to achieve higher conversion efficiency. The improvement plays an important role for achieving multi-bandgap tandem solar cell to break through the single-bandgap cell’s theoretically conversion efficiency in foreseeable future. In summary, this study demonstrates the P-doping effect on GSRO-ML Si QD thin films structure and the PV’s performances are greatly improved. The structure is potential and available to achieve high-efficiency solar cell in high-technology industry.
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Chen, Chen-Chia, and 陳振嘉. "Study of PZT thin films as medium for high density data storage applications." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/42884887256117990379.
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碩士國立雲林科技大學
電子與資訊工程研究所碩士班
91
The PZT is a ferroelectric oxide whose piezoelectric, dielectric, and ferroelectric properties make it attractive for many applications. It has been proposed as a high density storage medium and can be an integral component for applications like dynamic and nonvolatile random access memories. In this work, the PZT and LSMO precursors were prepared by sol-gel method. The precursors ware spin on variation of substrates then discussed with thermal stability、crystal structure and surface roughness. Finally the PZT thin film was grown on LSMO/SiO2/Si substrates A crystallization temperature of 750℃ was used, resulting in PZT thin films with a nano-grains of approximately 20-40 nm. Another goal is to establish tip-ferroelectric thin film system by means of parallel capacitance and image charge method. The system can simulate polarization field with respect to the parameters of tip bias 、dielectric constant of ferroelectric thin film and tip-sample distance and so on., to use of the system give us further understanding on the polarization phenomenon of tip-ferroelectric thin film, and also provide an preview of optimization on experiment conditions.
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Chen, You-Jheng, and 陳佑政. "Boron Doping Effect on the Super-High Density Si Quantum Dot Thin Films." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/24717970097630577489.
Full textAbstract:
碩士國立交通大學
光電工程研究所
102
In order to further reduce quantum dot (QD) separation, we had proposed and successfully developed the gradient Si-rich oxide multilayer (GSRO-ML) structure for the super-high density Si QD thin films with larger carrier tunneling probability. In this study, we investigate the B-doping and QD size effects on the super-high density Si QD thin films by using a GSRO-ML structure. Under B-doping effect, the preserved high crystallinity of Si QDs and the slightly reduced Eg with increasing PB are observed, besides, the electrical and PV properties are enhanced with increasing PB from 0 to 25W due to the increased active B-doped atoms but degraded at the higher PB than 30 W due to the increased inactive B-doped atoms and the interfacial over-diffusion of B-doped atoms. The decreased VOC with increasing PB due to the interfacial over-diffusion is efficiently improved by inserting the lowly B-doped GSRO thin films as buffer layers. Under QD size effect, the red-shift effect is clearly confirmed in the absorption band edge and quantum efficiency response with increasing NL thickness. Therefore, our results had demonstrated the feasibility and great potential for the higher efficiency Si-based solar cells integrating Si QDs by using a GSRO-ML structure.
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SHEN, KUO-YAO, and 沈國曜. "Preparation of Organic／Inorganic Silicon Dioxide Thin Films by High Density Plasma Deposition." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/85180011512651299408.
Full textAbstract:
碩士大葉大學
電機工程學系
103
This study prepare organic and inorganic silicon thin films using single chamber inductively coupled plasma chemical vapor deposition (ICP-CVD) system with gas mixture of tetramethylsilan (TMS), argon and oxygen (O2). The films are coated on polyethylene terephthalate (PET) substrates to investigate the water and oxygen resistant capabilities of the films. Firstly, we vary the temperature from 30-150 °C, power from 300 to 1800 W and O2/TMS gas ratio from 10 to 50, to determine the optimal deposition parameters for the low temperature silicon dioxides. The experimental results show that the density of the films increases when the temperature increases, but we keep the temperature at 90 °C due to the glass transition point of the PET substrate. At the power of 1200 W, the films have high Si-O-Si bonding configuration and density. At the O2/TMS ratio of 30, the films have less O-H bonding configuration and low void fraction. In addition, when varying the thickness of the silicon dioxides from 100 to 500 nm, the experimental results show that at the thickness of 300 nm, the WVTR of the film can reach 4.6×10-1 g/m2/day. We insert an organic silicon (SiCx:H) thin film between the silicon dioxide and the substrate to reduce the internal stress by counterbalancing the residual stress of the silicon dioxide. The experimental results show that the internal stress can decreases from -274 for the structure with only silicon dioxide to -35 MPa for the structure with silicon dioxide and organic silicon layer. As a consequence, the inorganic silicon layer can significantly reduce the internal stress and thus enhance the adhesion of silicon dioxide to flexible substrates. Furthermore, different pairs of organic/inorganic stacked layers are used as a water and oxygen resistant barrier. The experimental results show that the 6-pair can lead to better water and oxygen resistant properties. The 6-pair barrier shows a WVTR of 5.7×10-6 g/m2/day, hardness of 7H and adherence of 5B. Finally, the 6-pair barrier is used to encapsulate organic light-emitting diodes (OLEDs), and the device lifetime increases from 7 h before encapsulation to more than 200 h after encapsulation. As a result, the organic/inorganic thin films prepared in this study can resist water and oxygen, thus significantly increasing the lifetime of OLEDs. Keywords: inductively coupled plasma chemical vapor deposition, organic/inorganic thin film, residual stress, WVTR, organic light-emitting diode
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Chang, Jia-Ruei, and 張家瑞. "Phosphorous Doping Effect on the Super-High Density Si Quantum Dot Thin Films." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/03029864165879316474.
Full textAbstract:
碩士國立交通大學
光電工程研究所
103
Recently, the solar cells (SCs) integrating nano-crystalline Si quantum dot (nc-Si QD) thin films have been researched widely due to the highly-tunable ability of bandgap (Eg). Si-QD SCs can overcome the issue for energy loss from the high-energy photon due to the larger Eg than monocrystalline and amorphous Si. The general structure is Si QD embedded in SiO2 matrix utilizing [Si dioxide/Si rich oxide] multilayer ([SiO2/SRO]-ML) thin film structure. However, the poor photovoltaic (PV) properties were obtained due to naturally highly resistive properties of SiO2 matrix. Therefore, the reduction of QD separation, the increasing of QD density and the heavily impurities (B, P atoms, etc.) doping are available methods to enhance PV properties of devices. In 2013, we have proposed a new structure, gradient Si-rich oxide mutilayer (GSRO-ML) structure and demonstrated a super-high density Si QD thin film to reduce the separation between Si QDs which leads to the higher probability of carrier tunneling. To further enhance the PV properties, the boron doping effect on the super-high density Si QD thin film have been studied and the obvious improvement on PV properties can be observed. In this thesis, we propose to dope P atoms into GSRO-ML thin films by means of thermal diffusion of phosphorus oxide trichloride (POCl3). The P-doped effect and the issue of defect reduced of the P-doped super-high density Si QD thin film will be investigated and discussed. Under P-doping effect, the preserved crystallinity of Si QDs and high absorption coefficient are maintained. In addition, the electrical and PV properties are enhanced with increasing POCl3 flow rate from 280 to 880 sccm, and the best performance is obtained at 880 sccm due to the largest active P-doped atoms but decreased at 1000 sccm due to the increased inactive P-doped atoms. However, a harmful material for Si QD thin films, PCl5, was produced during the high temperature P doping process. We raise the O2 flow rate for the PCl5 reacted absolutely. The clear effect of defect reduced is observed, and the declined PV properties of devices have been observed. The phenomenon means the defect in matrix is helpful for carrier transport. Therefore, our result demonstrated the P-doping effect in the Si QD thin films by using a GSRO-ML structure.
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Chien, Yu-Jen, and 簡鈺人. "Deposition and Etching of Silicon Nitride Thin Films by High Density Plasma Chemical Vapor Deposition System." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/60354858961608028415.
Full textAbstract:
碩士逢甲大學
化學工程學所
91
Abstract An inductively coupled plasma chemical vapor deposition system was used to grow silicon nitride thin films. The thin films were divided into many layers by incorporating the plasma passivation in the deposition. The influences of deposition parameters, including ICP power、bias power、deposition pressure、deposition temperature、N2/SiH4 ratio、dilution gas and flow rate were studied. The effects of plasma treatment parameters, including plasma treatment time、treatment gas(N2) flow rate and treatment number were also investigated. FTIR、N&K analyzer、AFM、SIMS and stress meter were used to characterize the properties of the films, such as chemical bonding structure、thickness、refractive index、RMS roughness、hydrogen content and stress. An MIS structure Al/a-SiNx:H/P type Si wafer/Al was made for measuring the I-V curve. We have obtained a stable silicon nitride thin film with lower hydrogen content and smaller roughness of the surface comparing to those grown by normal method. This film was grown by dividing into many, about 30Å depositions and inserted the N2 plasma treatment to passivate the silicon nitride film, 10 seconds deposition immediately followed by 10 seconds plasma treatment for 20 cycles. The condition of deposition process for the this stable film was 900W ICP power、500W Bias power、20mTorr pressure、300℃ temperature、100/25 nitrogen-to-silane gas flow ratio、50sccm Ar and 50sccm He dilution gas flow rate, and the treatment gas, N2 flow rate was 200sccm.
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"Characterization of magnetic nanocomposite thin films for high density recording prepared by pulsed filtered vacuum arc deposition." 2004. http://library.cuhk.edu.hk/record=b6073751.
Full textAbstract:
by Chiah Man Fat."March 2004."
Thesis (Ph.D.)--Chinese University of Hong Kong, 2004.
Includes bibliographical references.
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Mode of access: World Wide Web.
Abstracts in English and Chinese.
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Chen, Tsai-Fu, and 陳再富. "Chemical-Vapor-Deposited Tantalum Pentoxide and Titanium Dioxide Thin Films for High-Density DRAM Storage Capacitor Applications." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/26672904563259867245.
Full textAbstract:
博士國立交通大學
電子工程學系
85
Two promising high dielectric constant materials for advanced DRAM storage capacitors: tantalum pentoxide (Ta2O5) and titanium dioxide (TiO2), were investigated in this thesis. These thin films were deposited by low pressure chemical vapor deposition (LPCVD). Post-deposition thermal treatments by rapid thermal annealing in N2O and furnace annealing in N2O are the most important contributions in our study. An in-situ sequential CVD deposition of multilayer TiO2/Ta2O5 composite films was proposed to achie both high dielectric constant and low leakage current simultaneously. CVD Ta2O5 films using tantalum pentaethylate(TaO(C2H5)5) source and O2 gas were deposited on phorphous-doped polycrystallinesilicon (n+ poly-Si) substrates and n- bare silicon wafers. Prior to filmdeposition, a rapid thermal nitridation (RTN) process had been taken to maximizethe charge storage efficiency and improve the electrical properties. The growth kinetic is thought to be a surface- reaction limited case due to an observed dependence of the deposition rate on the deposition temperature (350 ~ 580 C). A cross-sectional scanning electron microscopy (SEM) image shows anexcellent step coverage (~ 90 %) for CVD Ta2O5 film. Both the surface topography of as-deposited and annealed Ta2O5 films look rather smooth by AFM investigation. XRD pat
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Huang, Pin-Ruei, and 黃品睿. "High density Si quantum dot thin films using a gradient Si-rich oxide multilayer structure for photovoltaic devices application." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/rqe68w.
Full textAbstract:
碩士國立交通大學
顯示科技研究所
101
So far, the Si-based solar cell is the highest global market share and the good development potential due to the plentiful materials and the well-developed fabrication technique. In order to achieve the goal of the third generation solar cells with high efficiency and low cost, all Si-based multiple-junction solar cell is widely investigated and developed nowadays. The nano-crystalline Si quantum dot (QD) thin film is one of the potential structures to overcome the bandgap limitation of Si-based materials. Silicon-rich oxide (SRO) single layer and [SRO/SiO2] multilayer (ML) thin films are the most commonly used deposition structures for Si QD thin films. However, the former is hard to control the QD's size and density simultaneously, the latter exists the QD’s separation limitation due to the SiO2 barrier layers inserted. Furthermore, the QD’s density of both structures is still not high enough for a better PV application. These result in the difficulty for good photo-generated carrier’s transportation and high conversion efficiency. Hence, to efficiently improve the carrier’s transportation properties is a critical issue for the high efficiency Si-based solar cells integrating Si QD thin film. In this study, we propose a more potential deposition structure by a gradient Si-rich oxide multilayer (GSRO-ML) structure for the QD size control and the high QD density. The nano-structure, crystalline, and optical properties of Si QD thin films using a GSRO-ML structure had been studied. It also shows the better photovoltaic properties than that using a [SRO/SiO2]-ML structure. A higher conversion efficiency of Si QD thin films utilizing a GSRO-ML structure can be highly expected by using a heavy doping concentration in the near future.
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Chang, Chien-Pin, and 張建平. "Fabrication of thin-film silicon solar cells using high density plasma chemical vapor deposition and study of the activation characteristics of its related films." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/39987891199815671439.
Full textAbstract:
碩士華梵大學
電子工程學系碩士班
98
In this thesis, we studied how to fabricate amorphous silicon thin-film solar cells on a glass substrate. The experiment was divided into two major parts. In the first part, we started with the activation of amorphous silicon thin film on glass by microwave annealing technique. In the second part, we fabricated the amorphous silicon thin-film solar cells. At first, we tried to use the microwave annealing (MWA) system in the National Nano Device Laboratories (NDL) for the activation of amorphous silicon on glass. This was the first time use of MWA for amorphous silicon activation in Taiwan. We recorded all the details after MWA and compared the results with those for rapid thermal annealing (RTA). We found that, at the same process temperature, the microwave annealing technique had an advantage for the activation of amorphous silicon thin films. Secondly, we tried to use the high-density plasma chemical vapor deposition (HDP-CVD) to fabricate amorphous silicon thin-film solar cells on glass. We adjusted different gas flow to observe the quality of the films. Moreover, we used X-ray diffraction (XRD), Raman spectroscopy, n & k spectrometer, four-point probe and other equipments to carry out structural analysis of thin films. We also used a solar cell efficiency measuring system to analyze our solar cells. We have already achieved an amorphous silicon thin-film solar cell with photoelectric conversion efficiency as high as 3.85%.
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Excell, Peter S., and Z. M. Hejazi. "Compact Superconducting Dual-Log Spiral Resonator with High Q-Factor and Low Power Dependence." 2002. http://hdl.handle.net/10454/3260.
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NoA new dual-log spiral geometry is proposed for microstrip resonators, offering substantial advantages in performance and size reduction at subgigahertz frequencies when realized in superconducting materials. The spiral is logarithmic in line spacing and width such that the width of the spiral line increases smoothly with the increase of the current density, reaching its maximum where the current density is maximum (in its center for ¿/2 resonators). Preliminary results of such a logarithmic ten-turn (2 × 5 turns) spiral, realized with double-sided YBCO thin film, showed a Q.-factor seven times higher than that of a single ten-turn uniform spiral made of YBCO thin film and 64 times higher than a copper counterpart. The insertion loss of the YBCO dual log-spiral has a high degree of independence of the input power in comparison with a uniform Archimedian spiral, increasing by only 2.5% for a 30-dBm increase of the input power, compared with nearly 31% for the uniform spiral. A simple approximate method, developed for prediction of the resonant frequency of the new resonators, shows a good agreement with the test results.
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Chu, Cheng Hung, and 朱正弘. "Study of Silver Oxide Nano Thin Film of Ultra-high Density Optical Recording Disks." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/12180596877017382587.
Full textAbstract:
碩士國立臺灣海洋大學
光電科學研究所
93
In this thesis, we use pump-probe experiment, spectrometer, and transmission Electron microscopy to study the linear and nonlinear optical properties of silver oxide nano thin film under laser irradiation. First we sputter silver oxide thin film on copper grids and cover-glass (ZnS-SiO2/ AgOx/ZnS-SiO2) as near-field structure. Tune the flow rate of O2 when sputtering. We use optical microscope spectrometer to measure its transmittance and reflectance and pump-probe beam to write a matrix marks. Finally, compared with transmission Electron microscopy image and optical intensity image, the structures of dots and rings of written spots are observed in these processes.
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Thapliyal, Prashant. "High-K Dielectrics–Studies on (Ta2O5)1-x– (TiO2)x, (0 ≤ x ≤ 0.11), Thin Films." Thesis, 2021. https://etd.iisc.ac.in/handle/2005/5579.
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Recently the increasing demand for miniaturized electronic gadgets has raised the interest in searching the high dielectric constant (K) materials for memory elements. Among the investigated high dielectric constant metal oxides, complex perovskites, such as barium titanate, strontium titanate, etc. and their solid solutions; and binary oxides, such as tantalum pentoxide, titanium oxide, zirconium oxide, etc. and their solid solutions are prominent. Due to the toxicity and compatibility issues of many complex perovskite oxides with the current fabrication procedures, binary oxides have been a preferred choice to use as a gate dielectric in memory devices. Among the binary oxides, tantalum pentoxide (Ta2O5) was found to have high dielectric constant and good compatibility with the existing fabrication procedures of silicon devices and a potential to replace the silicon-based dielectrics, such as SiO2, SiOxNy, etc., in the memory devices. With the addition of TiO2, ZrO2, etc., the dielectric constant of bulk Ta2O5 was found to increase by manifold, and so the potential of miniaturization to improve in that proportion was envisaged.
The present study was carried out to search the high dielectric constant and low leakage current thin films of Ta2O5 ¬– TiO2 compositions for memory devices. Thin films of different compositions of (Ta2O5)1−x–(TiO2)x (TTOx) were prepared using mosaic and ceramic targets and the structural, electrical, and optical properties of prepared films were investigated. TTOx thin films with compositions, x = 0, 0.03, 0.06, 0.08, and 0.11, were deposited onto the silicon and quartz substrates by direct current (DC) magnetron sputtering. The as-deposited thin film samples were annealed, in the ambient air, at 500, 600, 700 and 800 ˚C, for 1.5 h. The dielectric constant was found significantly depending on the composition and annealing temperature. Among the prepared compositions, at 1 MHz, the highest dielectric constant 71 was observed for x = 0.06, annealed at 700 ˚C. Using the measured optical transmittance, different optical parameters, viz., refractive index, extinction coefficient, and optical bandgap of the prepared films were obtained and found strongly dependent on the annealing temperature. The observed current–voltage (I–V) characteristics show the decreasing leakage current density with increasing annealing temperature. On annealing at 800 ˚C, the C–V and I–V characteristics of the deposited film compositions were found affected significantly due to the growing interfacial SiO2 layer at the film–substrate (Si) interface. The electrical properties and existing different current conduction mechanisms in different electric field regions were observed depending on the growing interfacial SiO2 layer with increasing annealing temperature. A comparative study of the TTOx films of the same composition prepared following two different routes: first, by the radio frequency (RF) sputtering of the ceramic target; and second, by DC sputtering of mosaic (Ta, Ti) metal target, in the presence of oxygen, was also carried out. The same post-deposition treatment was followed for both types of films deposited from two different routes. The structural, electrical, and optical properties with current conduction mechanisms, for the films prepared from the two different routes, were measured, compared and analyzed. The observations have been described in the present thesis.
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Hsu, Chin-Hung, and 許欽宏. "Fabrication and technology development of high performance amorphous silicon-germanium thin-film solar cells by high-density-plasma deposition." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/78410210100824834622.
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Lin, Min-Ta, and 林明達. "Fabrication of A-Si Thin Film Transistor through an Enhanced Capacitive-Coupled High-Density Plasma Etcher." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/8a7uyj.
Full textAbstract:
碩士國立中興大學
材料科學與工程學系所
99
This thesis is used plasma etching technology for TFT LCD etching process, using the ECCP system to investigate the structure of a-Si. The main parameters used in these experiments were RF source power, RF bias power, SF6, He gas flow rates, chamber pressure. The study included the etching rate, uniformity, the product reaction and taper angle. Taguchi experimental design method to analyze the parameters, and finally proposes the optimal solution for the chamber pressure: 20mTorr, RF Source power: 9kW, RF Bias power: 12kW, Cl2 gas flow: 3600sccm, SF6 gas flow: 450sccm, He gas flow : 1000sccm. In order to solve the above problem, the systematic experimental data analysis was performed to determine the characteristic factors more efficiently. The experimental results, can be found the important factors for etching characteristics. Increase in chamber pressure makes worse to the etching angle, better to the etching uniformity. The main point of the etching angle is to selected chamber pressure in 20mT. Low frequency RF plasma source power 12000W is the best way for RF plasma source. The higher frequency RF plasma source power more intense bombardment to etching makes it possible to more effectively break Si-N bonds increase to the etching rate. Low power must be higher than the high-frequency power, it was the solution for the high-frequency RF plasma source power of 9000W, low frequency RF plasma source power is 12000W. SF6 etching gas flow rate increases makes worse to the etching angle, better to the etching uniformity. Have to take into account the main point of the etching uniformity SF6 gas flow was chosen as 450sccm. He was found in the experimental analysis was chosen for the not important factor for the 1000sccm.
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Lin, Yu-Hsin, and 林育新. "Fabrication of amorphous/microcrystalline silicon thin film solar cells at low temperature by high density plasma." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/82393600719251503490.
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Amorim, Carlos de Oliveira. "Experimental and modeling studies of magnetoelectric multiferroic heterostructured materials." Doctoral thesis, 2019. http://hdl.handle.net/10773/27751.
Full textAbstract:
Multiferroic materials are a very exotic type of materials which present simultaneously two or more ferroic properties. Magnetoelectric multiferroics, in particular, are a very prominent class of materials, mainly due to their outstanding foreseen applications such as magnetic sensors, energy harvester/conversion devices, and high efficiency memories. However, intrinsic magnetoelectric materials are quite rare and do not have, yet, the adequate properties to the everyday applications. One of the reasons for this to occur is due to the requirements for magnetism and ferroelectricity in matter being a priori contradictory, since the former needs unfilled dn orbitals, while the latter favours d0 orbitals. Nevertheless, extrinsic magnetoelectric multiferroics do not suffer from this problem because they do not share the same phase, hence being a very promising approach to engineer adequate magnetoelectric multiferroics. This thesis focus on the study of Fe and BaTiO3 systems as a means of achieving novel magnetoelectric effects. It is shown that a peculiar type of BaTiO3:Fe auto-composite presents an ordered magnetic behaviour, despite the concentration of Fe being as low as 113 atomic ppm. The Fe magnetization displays two abrupt changes in its spontaneous value, one with M/M ≈ 32% and the other with M/M ≈ 14%. These magnetic transitions are correlated the BaTiO3 orthorhombic↔tetragonal
and tetragonal↔cubic ferroelectric phase transitions. This magnetoelectric auto-composite was the motivation to resort to Density Functional Theory (DFT) modeling as a means to discover the microscopic mechanism(s) behind such a strong magnetoelectric effect. The study of an iron monolayer placed upon several possible BaTiO3 unit cells lead to the discovery of several interfaces with abrupt changes in their spontaneous magnetization, either through the enhancement and reduction of the Fe magnetic moments, or through the change between antiferromagnetic and ferromagnetic order of the Fe monolayer.
However, the highlight of these DFT studies lies in the discovery of a particular kind of interfaces, namely in the BTO221_2ndFe and BTO99_2ndFe
supercells, where there is a High-Spin–Low-Spin state transition which can quench completely the atomic magnetic moment of each of Fe atom, depending on the local crystal field felt by the Fe atoms. Based on this specific effect, where it is possible to turn on and off the magnetic moments of the Fe atoms, a magnetoelectric multiferroic device was proposed. Knowing the importance of the crystal field for the High-Spin–Low-Spin state transition, a thorough study regarding the Electric Field Gradient (EFG) of each possible BaTiO3 site was performed, resorting to a combined study of DFT and Perturbed Angular Correlations (PAC) spectroscopy. In this study, it was concluded that the PAC spectroscopy is not the most adequate hyperfine technique to be used in a quantitative study of the BaTiO3/Fe interfaces EFG tensor, due to the non-negligible effects of the radioactive probe on the BaTiO3 matrix. Finally, the deposition of BTO/Fe heterostructures on LaAlO3, MgO, Al2O3 and SrTiO3 substrates using RF-Sputtering, and the Molecular Beam Epitaxy (MBE) deposition of Fe layers on BaTiO3 cut at the (100), (110) and (111) planes were performed as an attempt to recreate the interfaces with the most appealing magnetoelectric effects predicted in the DFT modeling. The thin films deposited using sputtering showed the growth of many Fe, Ba-Ti-O and Fe-Ti-O oxides depending strongly on their substrate, as well as in the deposition and annealing conditions. Still no magnetoelectric coupling was observed in such thin films. On the other hand the Fe thin films deposited on BaTiO3 substrates showed large magnetoelectric couplings between the BaTiO3 ferroelectric phase transitions and the magnetization of the Fe layers (similarly to what happened in the BaTiO3:Fe auto-composite). The magnitude of this magnetoelectric couplings is strongly correlated with the BTO interface where the Fe was deposited, showing a huge change in spontaneous magnetization and coercivity for the rhombohedral↔orthorhombic ferroelectric phase transition up to M/M ≈ 148% and HC/HC ≈ 183% respectively for the (110) case.Materiais Multiferróicos são um tipo de materiais bastante exótico que apresentam simultaneamente dois ou mais tipos de propriedades ferróicas. Multiferróicos magnetoelétricos, em particular, são uma classe de materiais muito proeminente, principalmente devido às suas espantosas aplicações tecnológicas, tais como sensores magnéticos, dispositivos de conversão/colheita de energia, e memórias the alta eficiência. Todavia, materiais magnetoelétricos intrínsecos são verdadeiramente raros e ainda não possuem propriedades adequadas ao uso do dia-a-dia. Uma das razões para que isto aconteça prende-se com o facto dos requisitos para existência de magnetismo e ferroeletricidade na matéria serem a priori contraditórios, uma vez que enquanto os primeiros necessitam de orbitais dn semipreenchidas, os últimos tendem a favorecer orbitais d0. Porém, Multiferróicos magnetoelétricos extrínsecos não sofrem desta limitação pois não partilham a mesma fase sendo portanto uma abordagem promissora para a construção de um bom Multiferróico magnetoelétrico. Esta tese focar-se-á no estudo de sistemas contendo Fe e BaTiO3 como meio de se alcançarem novos efeitos magnetoelétricos. Um auto-compósito de BaTiO3:Fe é apresentado, que apesar da sua diminuta concentração de Fe (apenas 113 ppm atómicas), ainda assim apresenta um comportamento magnético ordenado. A magnetização do Fe apresenta duas variações bruscas no seu valor espontâneo, uma com M/M ≈ 32% e outra com M/M ≈ 14%. Estas transições magnéticas estão correlacionadas com as transições de fase ferroelétricas do BaTiO3 (ortorrômbica↔tetragonal e tetragonal↔cúbica). Este auto-compósito magnetoelétrico foi a motivação par ao uso da Teoria de Densidade Funcional (DFT) como meio para descobrir os mecanismos microscópicos por trás deste acoplamento magnetoelétrico tão intenso. O estudo de uma mono-camada de Fe colocada sobre várias células unitárias de BaTiO3 levaram à descoberta de várias interfaces com mudanças abruptas na sua magnetização espontânea, ora através do aumento ou diminuição dos momentos magnéticos do Fe, ora através da mudança entre a natureza antiferromagnética ou ferromagnética da camada de Fe. Contudo, o destaque dos estudos de DFT reside na descoberta de um tipo particular de interfaces onde ocorre uma transição de estado High-Spin–Low-Spin que consegue colapsar completamente o momento magnético atómico dos átomos de Fe, dependendo do campo cristalino local sentido por esses mesmos átomos. Baseado neste efeito, um dispositivo Multiferróico magnetoelétrico foi proposto. Sabendo a importância do campo cristalino para as transições de estado High-Spin–Low-Spin state, um estudo minucioso foi feito relativo ao gradiente de campo elétrico (EFG) nos sítios possíveis do BaTiO3, usando um estudo combinado entre Correlações Angulares Perturbadas (PAC) e DFT. Neste estudo, concluiu-se que PAC não é uma técnica hiperfina adequada para o estudo quantitativo do tensor EFG de interfaces de BaTiO3/Fe, dados os efeitos não desprezáveis das sondas radioativas na matriz de BaTiO3. Finalmente, foi feita a deposição de Heteroestruturas de BTO/Fe em substratos de LaAlO3, MgO, Al2O3 e SrTiO3 usando RF-Sputtering, assim como deposição de camadas de Fe em substratos de BaTiO3 cortados nos planos (100), (110) e (111) planes, usando Molecular Beam Epitaxy (MBE), numa tentativa de recrear as interfaces com efeitos magnetoelétricos mais apelativos, previstos pela modelação DFT. Os filmes finos depositados por sputtering mostraram o crescimento de múltiplos óxidos de Fe, Ba-Ti-O e Fe-Ti-O dependendo fortemente do substrato onde foram crescidos, assim como das condições de deposição e tratamentos térmicos. Porém, nenhum efeito magnetoelétrico foi observado nestes filmes. Por outro lado, os filmes depositados nos substratos de BaTiO3 mostraram grandes acoplamentos magnetoelétricos entre as fases ferroelétricas do BTO e a magnetização das camadas de Fe (à semelhança do que aconteceu no auto-compósito de BaTiO3:Fe). A ordem de grandeza destes acoplamentos está fortemente correlacionada com a interface do BTO onde o Fe foi depositado, apresentando uma enorme variação na magnetização espontânea e na coercividade para o caso da transição romboédrica↔ortorrômbica, até M/M ≈ 148% e HC/HC ≈ 183% respetivamente para o caso da orientação (110).
Tese realizada com apoio financeiro da FCT através da bolsa SFRH/BD/93336/2013.
Programa Doutoral em Física
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CHUANG, YING-HUNG, and 莊穎泓. "Growth of High-Quality Germanium Thin Film with Low Threading Dislocation Density by Using PLD and Its Application to Fabrication of PIN Photodetectors." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/05048382705367029653.
Full textAbstract:
碩士國立中正大學
物理系研究所
104
In this experiment, we use pulsed laser deposition (PLD) system which has not been used to grow germanium (Ge) epitaxial thin film. And we reduce particulates of droplet like that appear on surface of samples by inject a trace of argon and use pol-ished targets. Thus increase the surface flatness of samples. In PLD system, the deposition rate is controlled by the laser energy, so we can use lower growth temperature than other techniques. The most usual technique for grow epitaxial layer is CVD system, but it needs at least 600℃. And the high temper-ature will occur S-K mode, resulting raise roughness of surface. In this experiment, we can grow at 500℃. In addition, in epitaxial process, laser can give high power to Ge atoms, so after Ge atoms arrive the substrates, they still have enough energy to move to the position of lower free energy. Then form a well quality. After finish the epitaxial layer, we will use rapid thermal annealing (RTA). It can not only improve the crystallinity and also reduce the threading dislocation density (TDD). As aforementioned result, we already have a high-quality Ge thin film. Then we can use it into lithography process which we develop in this experiment. After that, we can assemble it into a photodetector and do the subsequent measurement.
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Chan, Feng-Ming, and 詹豐銘. "Study on Effects of Process Paramenters to Crystallinity and Doping Characteristics of Silicon Thin Film Deposited by High Density Plasma Chemical Vapor Deposition (HDPCVD)." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/89653949963544088676.
Full textAbstract:
碩士國立清華大學
電子工程研究所
97
In this research work, we use high density plasma chemical vapor deposition system to fabricate uc-Si/poly-Si films, and study the crystallinity and doping characteristics affected by adjustable process parameters, hydrogen dilution ratio, RF power, process pressure, substrate temperature, substrate biasing, doping gas flow rate, and finally analyze by XRD, SEM, Hall Measurement etc. In our research, we find the anomalous effect by hydrogen dilution ratio different from amount references, here we got the amorphous Si at dilution ratio at 99%, and poly-Si at lower dilution ratio, the lower hydrogen dilution ratio will result better crystallinity. Also we discover the doping gas flow rate will affect no matter the crystallinity or doping concentration. In our experiment, we got remarkable doping concentration at lower gas doping flow rate, 0.2sccm, and the crystallinity is only observed at this flow rate. We also focus on getting better doping concentration for N-type and P-type. As other references, n-type doping is easier than p-type. In our experiment, we got doping concentration 9 x 1018cm-3 at RF power 1000W，5.3x1015cm-3 at 900W for p-type；and 3 x 1020cm-3 at even lower than 900W for n-type, but in order to get higher doping concentration, lower doping gas flow rate is necessary.