Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Dielectrics.
Rozprawy doktorskie na temat „Dielectrics”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych rozpraw doktorskich naukowych na temat „Dielectrics”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
1
Fromille, Samuel S. IV. "Novel Concept for High Dielectric Constant Composite Electrolyte Dielectrics". Thesis, Monterey, California. Naval Postgraduate School, 2013. http://hdl.handle.net/10945/53408.
Pełny tekst źródłaStreszczenie:
Approved for public releaseThis research was part of an ongoing program studying the concept of multi-material dielectrics (MMD) with dielectric constants much higher than homogenous materials. MMD described in this study have dielectric constants six orders of magnitude greater than the best single materials. This is achieved by mixing conductive particles with an insulating surface layer into a composite matrix phase composed of high surface area ceramic powder and aqueous electrolyte. Specifically examined in this study was micron-scale nickel powder treated in hydrogen peroxide (H2O2) loaded into high surface area alumina powder and aqueous boric acid solution. This new class of dielectric, composite electrolyte dielectrics (CED), is employed in an electrostatic capacitor configuration and demonstrated dielectric constant of order 10 [raised to the 10th power] at approximately 1 Volt. Additionally, it is demonstrated that treated nickel can be loaded in high volume fractions in the CED configuration. Prior studies of composite capacitors indicated a general limitation due to shorting. This results from the onset of percolation due to excess loading of conductive phases. Insulated particles described herein are successfully loaded up to 40% by volume, far above typical percolation thresholds. Simple models are presented to explain results.
Lieutenant, United States Navy
2
Grove, Nicole R. "Characterization of functionalized polynorbornenes as interlevel dielectrics". Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/11204.
Pełny tekst źródła
3
Balu, Venkatasubramani. "Barium strontium titanate thin film capacitors for high-density memories /". Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
Pełny tekst źródła
4
Hu, Chuan. "Study of the thermal properties of low k dielectric thin films /". Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p9992820.
Pełny tekst źródła
5
Duong, Danny. "The complex dielectric properties of aqueous ammonia from 2 GHz - 8.5 GHz in support of the NASA Juno mission". Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42891.
Pełny tekst źródłaStreszczenie:
A new model for the complex dielectric constant, ε, of aqueous ammonia (NH4OH) has been developed based on laboratory measurements in the frequency range between 2-8.5 GHz for ammonia concentrations of 0-8.5 %NH3/volume and temperatures between 277-297 K. The new model has been validated for temperatures up to 313 K, but may be consistently extrapolated up to 475 K and ammonia concentrations up to 20 %NH3/volume. The model fits 60.26 % of all laboratory measurements within 2σ uncertainty. The new model is identical to the Meissner and Wentz (2004) model of the complex dielectric constant of pure water, but it contains a correction for dissolved ammonia. A description of the experimental setups, uncertainties associated with the laboratory measurements, the model fitting process, the new model, and its application to approximating jovian cloud opacity for NASA's Juno mission to Jupiter are provided.
6
Cicerrella, Elizabeth. "Dielectric functions and optical bandgaps of high-K dielectrics by far ultraviolet spectroscopic ellipsometry /". Full text open access at:, 2006. http://content.ohsu.edu/u?/etd,2.
Pełny tekst źródła
7
Cho, Taiheui. "Anisotropy of low dielectric constant materials and reliability of Cu/low-k interconnects /". Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
Pełny tekst źródła
8
Ahchawarattaworn, Jutharat. "Perovskite oxynitride dielectrics". Thesis, University of Newcastle Upon Tyne, 2011. http://hdl.handle.net/10443/1186.
Pełny tekst źródłaStreszczenie:
The synthesis, crystal structures and dielectric properties of perovskite oxynitrides of the type LnTiO2N (Ln = La, Nd and mixtures) and ATaO2N (A = Ca, Sr, Ba and mixtures), have been investigated. The end-member oxynitrides and their associated LaxNd1-xTiO2N, CaxSr1-xTaO2N and BaxSr1-xTaO2N solid solutions were successfully prepared by ammonolysis of the appropriate precursor oxides at temperatures in the range 900-1200ºC. The complete range of LaxNd1-xTiO2N solid solution are orthorhombic perovskites, which show a small increase in unit cell parameters with increasing La content across the range. Compositions in the CaxSr1-xTaO2N series are tetragonal for x < 0.6 and orthorhombic for x > 0.6. BaxSr1-xTaO2N solid solutions are tetragonal for x < 0.5 and cubic for x > 0.5. It was impossible to form any perovskite solid solution in the BaTaO2N-CaTaO2N series. Attempts were made to densify these oxynitrides by hot-pressing and spark plasma sintering, but a characteristic of all these oxynitride structures is that they are stable up to relatively low temperatures (1250oC) with decomposition occurring before any sintering can be achieved. A reducing environment is necessary to prevent oxidation, but this must not be too reducing to promote conversion of the transition metal into a lower oxidation state. As a result, fully dense samples were not obtained and dielectric property measurements could not be made on these samples. As an alternative, pure single phase LaTiO2N, NdTiO2N and LaxNd1-xTiO2N solid solutions were prepared as » 3 μm thick surface layers on dense pellets of the corresponding La2Ti2O7, Nd2Ti2O7 and (LaxNd1-x)2Ti2O7) oxides by ammonolysis. The bulk dielectric properties of these VI coated samples were then measured by LCR bridge techniques. The presence of an oxynitride layer significantly increased the measured dielectric constant of all samples, compared with the pure oxides, but a significantly higher dielectric loss was also observed. This lossy behaviour is believed to be due to the presence of a more conductive region of reduced La2Ti2O7 (of typical composition 2 2 7 La TiIV TiIIIO -x x -z ) situated immediately below the oxynitride layer, produced during synthesis by the presence of hydrogen in the nitriding ammonia atmosphere. The dielectric constant of all these oxynitrides was also measured in particulate form by impedance analysis of slurries and the dielectric constant calculated by a method of mixtures. Compared with the parent oxides, the dielectric constants were noticeably larger, ranging from 100-1500. These values are in reasonable agreement with the limited amount of data available in the literature, and show that this group of materials merits further exploration, providing easier synthesis routes can be developed, which also result in low loss final materials being obtained.
9
Saura, Mas Xavier. "Filamentos conductores de ruptura dieléctrica en aislantes delgados". Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/285732.
Pełny tekst źródłaStreszczenie:
La industria micro y nanoelectrónica requiere de múltiples líneas de investigación para la introducción de continuas mejoras en los dispositivos en términos de rendimiento, funcionalidad y escalabilidad. Una de estas mejoras se centra en la idea de utilizar el fenómeno de la ruptura dieléctrica como principio de operación de dispositivos electrónicos. Esta idea ha generado mucho interés recientemente, especialmente en el campo de las memorias no volátiles.
Así, la investigación realizada a lo largo de esta tesis doctoral gira en torno a la ruptura dieléctrica de óxidos de alta permitividad y la posterior conducción filamentaria observada en capacidades metal-aislante-semiconductor (MOS) y metal-aislante-metal (MIM). En concreto, este trabajo se ha centrado en el estudio de tres principales objetivos que han concluido con la publicación de varios artículos, los cuales han permitido presentar esta tesis como compendio de publicaciones.
Por un lado, se muestran los resultados del estudio realizado en relación con el fenómeno de conmutación resistiva observado en capacidades MOS, poniendo especial interés en el fenómeno de Threshold Switching el cual ha sido analizado en términos del modelo de contacto puntual cuántico. Por otro lado, se describen los resultados obtenidos en relación con el estudio y exploración del efecto de campo sobre caminos de ruptura dieléctrica generados en estructuras MIM planares. Para ello se ha realizado el diseño, simulación, fabricación y caracterización de varios dispositivos específicos cuyas dimensiones críticas son del orden de pocos nanómetros. De la caracterización de estas estructuras se han obtenido resultados que muestran indicios del efecto de campo sobre dichos caminos. Por último, se analiza la estadística espacial y temporal de múltiples caminos de ruptura observados en el electrodo superior de capacidades MOS y MIM obtenidos a partir del estrés eléctrico aplicado sobre las mismas. En este sentido, se han desarrollado tres métodos de análisis de distribuciones estadísticas para detectar posibles desviaciones respecto a un proceso aleatorio espacial completo: el primero basado en las distancias entre filamentos vecinos de orden k; el segundo relacionado con la caracterización espacio-temporal de los filamentos; y por último un método en el que se han desarrollado expresiones para el estudio de las distribuciones estadísticas de las distancias y ángulos de los spots en relación a un punto fijo asociado a la punta de inyección de carga utilizada para la generación de los eventos.Micro and nanoelectronics industry requires multiple lines of research for introducing continuous improvements in electronic devices in terms of performance, functionality and scalability. One of these improvements focuses on the idea of using the dielectric breakdown phenomenon as a principle of operation of these devices. This idea has generated much interest recently, especially in the field of non-volatile memories. Thus, the research done in this thesis focuses its attention around the dielectric breakdown phenomena and the subsequent filamentary conduction observed in metal-oxide-semiconductor (MOS) and metal-insulator-metal (MIM) devices with high dielectric permittivity. Specifically, this work focuses on the study of three main objectives which have resulted in the publication of several articles and this has allowed presenting the thesis as a compendium of publications. The study shows results in relation to the resistive switching phenomenon observed in MOS devices, with particular interest in the phenomenon of Threshold Switching described in terms of the quantum point contact model. Furthermore, results regarding the study of the field-effect on dielectric breakdown paths generated in planar MIM structures are also described. With this goal, it is shown the design, simulation, fabrication and characterization of several devices whose critical dimensions are in the order of a few nanometers. The characterization of these structures shows preliminary results that point in the direction of the expected field effect. Finally, the spatial and temporal statistics of multiple breakdown paths, observed in the top electrode of MOS and MIM capacitors as a result of the applied electrical stress, is analyzed. Three methods were developed to analyze statistical distributions for detecting possible deviations from a complete spatial random process. One is based on the distances between neighboring filaments of order k; the second one concerns the spatio-temporal characterization of the observed filaments; and finally a method is presented, in which expressions have been developed, for the study of the statistical distributions of the distances and angles of the spots relative to a fixed point, which is associated with the charge injection point used in the generation of events.
10
Cousins, Jesse. "Simulation of the Variability in Microelectronic Capacitors having Polycrystalline Dielectrics with Columnar Microstructure". Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/CousinsJL2003.pdf.
Pełny tekst źródła
11
Bae, Choelhwyi. "GaN-dielectric interface formation for gate dielectrics and passivation layers using remote plasma processing". NCSU, 2003. http://www.lib.ncsu.edu/theses/available/etd-05082003-023332/.
Pełny tekst źródłaStreszczenie:
In previous studies, device quality Si-SiO2 interfaces and dielectric bulk films (SiO2) were prepared using a two-step process; i) remote plasma-assisted oxidation (RPAO) to form a superficially interfacial oxide (~0.6 nm) and ii) remote plasma enhanced chemical vapor deposition (RPECVD) to deposit the oxide film. The same approach has been applied to the GaN-SiO2 system. After a 300 oC remote N2/He plasma treatment of the GaN surface, residual C and Cl were reduced below Auger electron spectroscopy (AES) detection, and the AES peak ratio of O KLL and N KLL was ~0.06 or ~0.1 monolayer of oxygen. RPAO of GaN surfaces using O2, N2O, and N2O in N2 source gases were investigated by on-line AES to determine the oxidation kinetics and chemical composition of the interfacial oxide. Without an RPAO step, subcutaneous oxidation of GaN takes place during RPECVD deposition of SiO2, and on-line AES indicates a ~0.6-0.8 nm subcutaneous oxide. Compared to single step SiO2 deposition, significantly reduced interface state density (Dit) was obtained at the GaN-SiO2 interface by independent control of GaN-Ga2O3 interface formation by thin RPAO oxide (~1 nm) and SiO2 film deposition by RPECVD. High-low frequency method and conductance method indicate that Dit of GaN Metal-Oxide-Semiconductor (MOS) sample without RPAO is ~5 times larger than that of the sample with RPAO. For the GaN MOS structure with remote plasma oxidation and nitridation, Dit determined at DCmax was low-to-mid x 1011 cm-2eV-1. Also, we report on high temperature and photo-assisted capacitance-voltage (C-V) characteristics.
12
Tavassolian, Negar. "Dielectric charging in capacitive RF MEMS switches with silicon nitride and silicon dioxide". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39504.
Pełny tekst źródłaStreszczenie:
Capacitive radio frequency (RF) micro-electromechanical (MEMS) switches are among the most promising applications in MEMS systems. They have been introduced in the last 15-20 years as a practical alternative over traditional semiconductor switches. Low-cost RF MEMS switches are prime candidates for replacing the conventional GaAs Field Effect Transistors (FET) and pin diode switches in RF and microwave communication systems, mainly due to their low insertion loss, good isolation, linear characteristic and low power consumption. Unfortunately, their commercialization is currently hindered by reliability problems. The most important problem is charging of the dielectric, causing unpredictable device behavior. The charging of the dielectric has been found to be a complicated process and is currently under intense research. Developing a good analytical model that would describe accumulating of charges in the dielectric and their influence on the device behavior would be the main step to achieving more reliable switches. This work intends to theoretically and experimentally investigate the dielectric charging effects of capacitive RF MEMS switches with silicon nitride and silicon dioxide as the dielectric layer. For the silicon nitride study, both MEMS switches and MIM capacitors were fabricated, and their charging behaviors were analyzed and compared. Several different dielectric stoichiometries, deposition temperatures, and thicknesses were examined in order to understand the effects of each parameter on the charging mechanisms of the dielectric. The goal was to determine the most favorable deposition conditions to induce minimum dielectric charging in silicon nitride capacitive switches. The switches were measured over a wide temperature range and the temperaturedependent behavior of the dielectric was examined to characterize and study its charging behaviors. For the silicon dioxide MEMS switches, several different actuation mechanisms were systematically analyzed, and their effects on the dielectric charging of the switches were studied. A general model of distributed charge and air gap was adopted and further developed to better explain the charging behavior of MEMS switches. The goal was to provide a deeper insight into the trapping processes in dielectric materials and their corresponding time constants. This will in turn aid in better modeling of charging processes in capacitive RF MEMS switches.
13
Kleemann, Tobias A. "An investigation into solid dielectrics". Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/346911/.
Pełny tekst źródłaStreszczenie:
Direct measurement techniques for the investigation of electrical processes in solid dielectrics are reviewed and their respective strengths and weaknesses are discussed, particularly the complementary nature of thermally stimulated current measurements. The successful design and construction of a new Thermally Stimulated Discharge Current (TSDC) Spectrometer at the University of Southampton is presented and its correct function validated with experimental measurements of the well known and often characterized synthetic polymers low density polyethylene (LDPE) and polyethylene terephtalate (PET). Results were found to correspond well to published data. First TSDC observations of filled and oil impregnated papers are presented. The second aspect of this work is the investigation of natural polymer insulation materials,specifically paper for oil-paper insulation systems. For the first time, electrical insulation papers with filler contents up to 50% were investigated. Bentonite and talcum were compared as filler materials and found to have negative and positive effects respectively. The superior electrical strength of a talcum filled kraft paper was verified, and a series of constructive modifications was undertaken to further maximise its electrical strength at comparable or improved dielectric performance. An increase in electrical breakdown strength of 20% to 30% has been observed, but the substitution of such great amounts of fiber with fillers also lead to a reduction in mechanical strength of the paper. Further trials with chemical additives were conducted to counteract this effect and polyvinyl alcohol and starch were found to enhance the paper strength. Additional trials also comprised sizing agents, guar gum and wet strength agents. Uncharged or slightly charged chemical additives provided best results with regard to dielectric performance. The significance of the trialled paper modifications is judged in light of statistical analysis.
14
Addington, J. Shawn. "Wideband electrical characterization of multilayer low-loss dielectric materials". Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-10312009-020154/.
Pełny tekst źródła
15
Hasegawa, Keisuke. "The effect of geometry and surface morphology on the optical properties of metal-dielectric systems /". Connect to title online (Scholars' Bank) Connect to title online (ProQuest), 2008. http://hdl.handle.net/1794/8581.
Pełny tekst źródłaStreszczenie:
Thesis (Ph. D.)--University of Oregon, 2008.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 127-133). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.
16
Hare, Richard W. "Modelling space charge in solid dielectrics". Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.482030.
Pełny tekst źródła
17
Lu, Yi. "High-k dielectrics for CMOS application". Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437492.
Pełny tekst źródła
18
Tear, Gareth Richard. "Shock properties of homogeneous anisotropic dielectrics". Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/53828.
Pełny tekst źródłaStreszczenie:
Anisotropy, the directional dependence of a physical quantity, is present in numerous physical processes involved in the shock compression of solid materials. The effect that a particular property’s anisotropy has on the propagation of a shock wave is obscured by other effects such as those from strain rate and material heterogeneity. Recent studies have focussed on single- and bi-crystal metals to understand the effect of crystal anisotropy on the mechanics of shock wave propagation. This thesis extends this work to optically transparent non-metallic dielectric single crystals by developing an optical model for anisotropic dielectrics and performing experimental measurements to test the validity of that optical model. Current optical models for shock compressed materials use an isotropic Gladstone- Dale model or isotropic modifications of the Gladstone-Dale model. This thesis extends the isotropic Gladstone-Dale model to an anisotropic photoelastic model for the optical behaviour of linear anisotropic materials under shock compression in the elastic regime. The model uses static photoelastic tensor values available in the literature to predict material response under uniaxial strain in an arbitrary crystal orientation. The effect of varying photoelastic tensor values is studied using Monte Carlo techniques, and confidence intervals on dynamic predictions are presented. Polarimetry is applied to experimentally measure birefringence under shock compression delivered using plate impact on a single stage light gas gun. This method is used to validate the linear photoelastic model developed in this thesis. Experiments were performed on < 10-10 > (a-cut) sapphire up to 15 GPa longitudinal stress and < 10-10 > (a-cut) calcite up to 2 GPa longitudinal stress. It was found that the birefringence of a-cut sapphire under shock compression behaved in agreement with the model in the elastic regime for a 5% error on the photoelastic tensor. Furthermore it was found that birefringence predictions for a-cut calcite as given by the same model did not agree with experimentally measured results. The discrepancy was 0.3% at 1.2 GPa, in excess of 5 standard deviations. Possible reasons for the discrepancy are put forward. Current optical models for shock compressed materials use an isotropic Gladstone-Dale model or isotropic modifications of the Gladstone-Dale model. This thesis extends the isotropic Gladstone-Dale model to an anisotropic photoelastic model for the optical behaviour of linear anisotropic materials under shock compression. The model uses static photoelastic tensor values available in the literature to predict material response under uniaxial strain in an arbitrary crystal orientation. The effect of varying photoelastic tensor values is studied using Monte Carlo techniques, and confidence intervals on dynamic predictions are presented. Polarimetry is applied to experimentally measure birefringence under shock compression. This method is used to validate the linear photoelastic model developed in this thesis. Experiments were performed on ⟨1 0 1 0⟩ (a-cut) sapphire and ⟨1 0 1 0⟩ (a-cut) calcite. It was found that the birefringence of a-cut sapphire under shock compression behaved in agreement with the model. Furthermore it was found that birefringence predictions for a-cut calcite as given by the same model did not agree with experimentally measured results. Possible reasons for the discrepancy are put forward.
19
Murad, S. N. A. "High-ĸ gate dielectrics on germanium". Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.680229.
Pełny tekst źródłaStreszczenie:
Germanium is an attractive channel material for MOSFETs because of its higher mobility than silicon. Ge02 has been investigated as an interfacial layer for high-K gate stacks on germanium. Thermally grown Ge02 layers have been prepared at 550°C to minimize GeO volatilization. Ge02 growth has been performed in both pure O2 ambient and O2 diluted with N2. Ge02 thickness has been scaled down to approximately 3 nm. This is the first time ever Ge02 has been scaled using dilution method. MOS capacitors have been fabricated using Ge02 grown in various ambient and different thicknesses with a standard high-K dielectric on top. Electrical properties and thermal stability have been tested up to at least 350°C. The K value of Ge02 was experimentally determined to be 4.5. Interface state densities (Did of less than 1012 cm-2eV-1 have been extracted for all devices using the conductance method.
20
Truong, L. H. "Dielectrics for high temperature superconducting applications". Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/355538/.
Pełny tekst źródłaStreszczenie:
This thesis is concerned with the development of condition monitoring for future design of high temperature superconducting (HTS) power apparatus. In particular, the use of UHF sensing for detecting PD activity within HTS has been investigated. Obtained results indicate that fast current pulses during PD in LN2 radiate electromagnetic waves which can be captured by the UHF sensor. PD during a negative streamer in LN2 appears in the form of a series of pulses less than 1 μs apart. This sequence cannot be observed using conventional detection method due to its bandwidth limitation. Instead, a slowly damped pulse is recorded which shows the total amount of charge transferred during this period. A study into PD streamer development within LN2 has been undertaken that reveals the characteristics of pre-breakdown phenomena in LN2. For negative streamers, when the electric field exceeds a threshold value, field emission from the electrode becomes effective which leads to the formation of initial cavities. Breakdown occurs within these gaseous bubbles and results in the development of negative streamers. For positive streamers, the process is much less well-understood due to the lack of initial electrons. However, from the recorded current pulses and shadow graphs, the physical mechanism behind positive streamer development is likely to be a more direct process, such as field ionisation, compared with the step-wise expansion in the case of negative streamers. The mechanisms that cause damage to solid dielectrics immersed in LN2 have been investigated. Obtained results indicate that pre-breakdown streamers can cause significant damage to the solid insulation barrier. Damage is the result of charge bombardment and mechanical forces rather than thermal effects. Inhomogeneous materials, such as glass fibre reinforced plastic (GRP), tend to introduce surface defects which can create local trapping sites. The trapped charges when combined with those from streamers can create much larger PD events. Consequently, damage observed on GRP barriers is much more severe than that on PTFE barriers under similar experimental conditions. Thus, design of future HTS power apparatus must consider this degradation phenomenon in order to improve the reliability of the insulation system.
21
Blanchard, John L. "Integral equation analysis of artificial dielectrics". The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1314649696.
Pełny tekst źródła
22
Mathew, Anoop. "Interfacial phenomena in high-kappa dielectrics". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 118 p, 2009. http://proquest.umi.com/pqdweb?did=1654501721&sid=4&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Pełny tekst źródła
23
Jan, Saeed Ullah. "Dielectrics for high temperature capacitors applications". Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/11528/.
Pełny tekst źródłaStreszczenie:
Most of the dielectric materials developed in this thesis were relaxor dielectrics with very broad, frequency dependent peaks in relative permittivity-temperature, εr – T, plots. In some cases, plateau-like permittivity plots with very wide temperature ranges of stable permittivity varying by no more than ±15 % were obtained through compositional engineering of the relaxor base material using high levels of lattice substitution of cations of different charge and size to the host lattice. The solid solution series (1–x)Na0.5Bi0.5TiO3 – xBa0.8Ca0.2TiO3 [(1–x)NBT–xBCT] was studied initially: it showed little evidence of temperature-stable relative permittivity. However, 0.85NBT – 0.15BCT ceramics modified by BiMg0.5Ti0.5O3, [BMT], were more promising. The series, (1–x)[0.85Na0.5Bi0.5TiO3 – 0.15Ba0.8Ca0.2TiO3] – xBiMg0.5Ti0.5O3, x = 0.3, gave εr ~ 1720 ± 15 %, in the temperature range 120 to 450 ºC, and low dielectric loss tangent, tanδ ≤ 0.02, over the slightly narrower temperature range, 150 to 360 ºC. Thus an upper operating temperature > 300°C was demonstrated but without also achieving sub-zero temperature capability. Similarly, the system (1–x)[0.85Na0.5Bi0.5TiO3 – 0.15Ba0.8Ca0.2TiO3] – xLiNbO3 abbreviated [(1–x)[NBT – BCT] – xLN] gave εr ~ 2630 ± 15 % from 50 ºC to 410 ºC, and tanδ ≤ 0.02 from 120 ºC to 400 ºC, at composition x = 0.06. The incorporation of NaNbO3 [NN] in place of LiNbO3 achieved the desired sub-zero temperature capability in relative permittivity, and with an upper temperature limit slightly above 200 ºC. Examples include (1–x)[NBT – BCT] – xNN composition x = 0.3 with εr = 1400 ± 15 % from -50 to 240 °C and tanδ ≤ 0.02 from 20 ºC to 240 v ºC; for x = 0.4, εr = 1300 ± 15 % from -70 to 210 °C and tanδ ≤ 0.02 from -10 ºC to 210 ºC. In terms of the project goal of achieving a temperature range of stable permittivity combined with a low loss extending from temperatures of -55 °C (to meet the Electronic Industry Alliance military specification) up to 300 °C, the binary solid solution system (1–x)Ba0.6Sr0.4Zr0.2Ti0.8O3 – xBiMg0.5Ti0.5O3 [(1–x)BSZT – xBMT] was most promising. However there was a trade-off in that permittivity values were lower than the foregoing systems. The (1–x)BSZT – xBMT sample composition x = 0.2 gave εr ~ 500 ± 15%, in the temperature range -70 to 300 ºC and tanδ ≤ 0.02, in the range -60 to 300 ºC. This system closely matches the target temperature-range of the project, but the volumetric efficiency of a capacitor made from this dielectric would be compromised due its moderate relative permittivity values. Slightly higher values of relative permittivity were obtained for x = 0.3 in the (1–x)BSZT – xBMT series, with εr ~ 590 ± 15%, across the temperature range -60 to 340 ºC, but in this case the temperature range of low dielectric losses tanδ ≤ 0.02 was restricted to -10 to 280 ºC. Piezoelectric properties of selected samples have also been investigated in the thesis.
24
Xu, Yifan. "Studies on field effect transistors with conjugated polymer and high permittivity gate dielectrics using pulsed plasma polymerization". Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1124219179.
Pełny tekst źródłaStreszczenie:
Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xx, 187 p.; also includes graphics (some col.). Includes bibliographical references (p. 174-187). Available online via OhioLINK's ETD Center
25
Pothukuchi, Suresh V. "Development of a polymer-metal nanocomposite dielectric by in situ reduction for embedded capacitor application". Thesis, Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04072004-180141/unrestricted/pothukuchi%5Fsuresh%5Fv%5F200312%5Fms.pdf.
Pełny tekst źródła
26
Yang, Fan. "Characterization of HFO2 Capacitors". Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/YangF2003.pdf.
Pełny tekst źródła
27
Taechakumput, Pouvanart. "Novel high-K dielectrics for MOS applications". Thesis, University of Liverpool, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490807.
Pełny tekst źródłaStreszczenie:
The ever increasing demand for improved performance of silicon based microelectronics, at a lower cost, has resulted in an aggressive reduction, or scaling, in the dimensions of the metal-oxide-semiconductor field effect transistors (MOSFET) in integrated circuits (IC). Silicon oxynitride-based gate dielectrics (SiON) have been u~ed in MOSFETs, due to their stable high quality interface with the silicon channel and excellent electrical isolation properties. However, the transistor feature size the gate dielectric has recently been reduced to the point where direct electron tunnelling effects and the leakage currents presented serious problems to device performance in sub-90 nm node IC technology. The same problem also occurs in dynamic random access memory (DRAM), another key device component in the silicon microelectronics industry which faces the challenge of increasing the effective capacitor area without'increasing its footprint in the cell. Alternatively, the use of materials with a higher dielectric permittivity (high-k or Ek) than that of Si02 (Ek = 3.9) allows an equivalent capacitance to be achieved in a physically thicker insulating layer which leads, in tum, to reduced leakage currents. Such materials includes: (i) the metal oxides (e.g., Hf02, Zr02 and Y203); (ii) the lanthanide oxides (e.g., Pr203, Gd20 3 and Ln203); and (iii) the pseudobinary alloys (e.g., ZrSixOyand NdAIOx). In this thesis, physical and electrical characteristics of the deposited high-k materials (Hf02 and NdAIOx) were thoroughly investigated. Both the atomic layer deposition (ALD) and metalorganic chemical vapour deposition (MOCVD) methods were applied in fabricating high-k dielectrics using novel precursors. The chemical vapour deposition (CVD) method is introduced and discussed and the applications of the high-k dielectrics in microelectronics are reviewed. The effect of heat treatment, both prior to and after gate metallization, on the film crystallinity and the associated electrical properties was examined in detail. Electrical measurements, of the materials studied, showed promising dielectric properties such as high permittivity values and low leakage current densities. Other properties, such as microstructures, interfacial layer thickness and morphology were also characterized. The origin of frequency dispersion effects, frequently observed in C-V measurements, was also systematically investigated. Finally,.a novel reconstruction model has also been implemented for C-V measurements in order to minimize the measurement errors using the adapted dual frequency technique. It is believed that these results will be of significant interest to both academic and industrial researchers in this fast moving field.
28
McElcheran, Clare. "Understanding Femtosecond Laser Modification of Bulk Dielectrics". Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28633.
Pełny tekst źródłaStreszczenie:
The minimum spacing of a plasma waveguide was calculated and applied to the formation of periodic nanocracks. The minimum spacing decreased with decreasing plasma frequency but was found to have limited effect on the spacing of the nanocracks.
An extension to a standard Finite-Difference Time-Domain method was created to include nonlinear processes and the dynamic build up of the electron plasma. The ionized area produced in the simulation agrees with experiment. The existence of a self-limited absorption effect on a Gaussian pulse in time was verified in the simulations. The region was elongated along the direction parallel to the polarization of the light. The multiphoton absorption was found to be the main cause of the distinct shape of the damaged area. Plasma dispersion and self-focusing create larger electron densities and a shift in the location of the electron density peak, but did not affect the general shape.
29
Chambers, James Joseph. "REACTIONS FOR YTTRIUM SILICATE HIGH-K DIELECTRICS". NCSU, 2000. http://www.lib.ncsu.edu/theses/available/etd-20000721-183205.
Pełny tekst źródłaStreszczenie:
CHAMBERS, JAMES JOSEPH. Reactions for Yttrium SilicateHigh-k Dielectrics. (Under the advisement of Dr. GregoryN. Parsons.)The continued scaling of metal-oxide-semiconductor-field-effect-transistors (MOSFETs) will require replacing the silicon dioxide gate dielectric with an alternate high dielectric constant (high-k) material. We have exploited the high reactivity of yttrium with both silicon and oxygen to form yttrium silicate high-k dielectrics. Yttrium silicate films with composition of (Y)1-x and x = 0.32 to 0.87 are formed by oxidizing yttrium on silicon where yttrium reacts concurrently with silicon and oxygen. The competition between silicon and oxygen for yttrium is studied using X-ray photoelectron spectroscopy (XPS) and medium energy ion scattering (MEIS). The initial yttrium thickness mediates the silicon consumption, and a critical thickness (~40-80 Å) exists below which silicon is consumed to form yttrium silicate and above which Y forms without silicon incorporation. Engineered interfaces modify the silicon consumption, and a nitrided silicon interface results in film with composition close to Y. The silicon consumption also depends on the oxidation temperature, and oxidation at higher temperature generally results in greater silicon incorporation with an activation energy of 0.3-0.5 eV. Yttrium silicate films (~40 Å) formed by oxidation of yttrium on silicon have an amorphous microstructure and an equivalent silicon dioxide thickness of ~12 Å with leakage current . Yttrium silicate formation on silicon is also demonstrated using plasma oxidation of yttrium on silicon, reactive sputtering of yttrium and annealing/oxidation of yttrium on thermal SiO. The interface reactions described here for yttrium are expected to be active during both physical and chemical vapor deposition of other high-k dielectrics containing Hf, Zr and La.
30
Wubs, Cornelis Martijn. "Quantum optics and multiple scattering in dielectrics". [S.l : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2003. http://dare.uva.nl/document/70167.
Pełny tekst źródła
31
Farnsworth, Kimberly Dawn Richards. "Variable frequency microwave curing of polymer dielectrics". Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/10928.
Pełny tekst źródła
32
Jubber, Michael G. "Laser production of patterned interconnects and dielectrics". Thesis, Heriot-Watt University, 1991. http://hdl.handle.net/10399/825.
Pełny tekst źródła
33
Bugler-Lamb, Samuel Lloyd. "The quantum vacuum near time-dependent dielectrics". Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/29879.
Pełny tekst źródłaStreszczenie:
The vacuum, as described by Quantum Field Theory, is not as empty as classical physics once led us to believe. In fact, it is characterised by an infinite energy stored in the ground state of its constituent fields. This infinite energy has real, tangible effects on the macroscopic clusters of matter that make up our universe. Moreover, the configuration of these clusters of matter within the vacuum in turn influences the form of the vacuum itself and so forth. In this work, we shall consider the changes to the quantum vacuum brought about by the presence of time-dependent dielectrics. Such changes are thought to be responsible for phenomena such as the simple and dynamical Casimir effects and Quantum Friction. After introducing the physical and mathematical descriptions of the electromagnetic quantum vacuum, we will begin by discussing some of the basic quasi-static effects that stem directly from the existence of an electromagnetic ground state energy, known as the \textit{zero-point energy}. These effects include the famous Hawking radiation and Unruh effect amongst others. We will then use a scenario similar to that which exhibits Cherenkov radiation in order to de-mystify the 'negative frequency' modes of light that often occur due to a Doppler shift in the presence of media moving at a constant velocity by showing that they are an artefact of the approximation of the degrees of freedom of matter to a macroscopic permittivity function. Here, absorption and dissipation of electromagnetic energy will be ignored for simplicity. The dynamics of an oscillator placed within this moving medium will then be considered and we will show that when the motion exceeds the speed of light in the dielectric, the oscillator will begin to absorb energy from the medium. It will be shown that this is due to the reversal of the 'radiation damping' present for lower velocity of stationary cases. We will then consider how the infinite vacuum energy changes in the vicinity, but outside, of this medium moving with a constant velocity and show that the presence of matter removes certain symmetries present in empty space leading to transfers of energy between moving bodies mediated by the electromagnetic field. Following on from this, we will then extend our considerations by including the dissipation and dispersion of electromagnetic energy within magneto-dielectrics by using a canonically quantised model referred to as 'Macroscopic QED'. We will analyse the change to the vacuum state of the electromagnetic field brought about by the presence of media with an arbitrary time dependence. It will be shown that this leads to the creation of particles tantamount to exciting the degrees of freedom of both the medium and the electromagnetic field. We will also consider the effect these time-dependencies have on the two point functions of the field amplitudes using the example of the electric field. Finally, we will begin the application of the macroscopic QED model to the path integral methods of quantum field theory with the purpose of making use of the full range of perturbative techniques that this entails, leaving the remainder of this adaptation for future work.
34
Zhang, Xuewei. "Keer electro-optic measurements in liquid dielectrics". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91035.
Pełny tekst źródłaStreszczenie:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
Kerr electro-optic technique has been used to measure the electric field distribution in high voltage stressed dielectric liquids, where the difference between refractive indices for light polarized parallel and perpendicular to the local electric field is a function of the electric field intensity. For transformer oil, the most widely-used insulating liquids in power apparatus and high voltage technology, Kerr effect is very weak due to its low Kerr constant. Previous Kerr measurements have been using ac modulation technique, which is only applicable to dc steady-state electric field mapping while various instabilities develop in liquid under long-term high voltage application. The use of the high-sensitivity CCD camera as optical detector makes it possible to capture the weak Kerr effect in high voltage stressed transformer oil. The first part of this thesis is to demonstrate the reliability and evaluate the sensitivity of the measurements for various cases with identical electrodes under pulsed excitation with insignificant flow effects. After the validation and optimization of the experimental setup, measurements are taken to record the time evolution of electric field distributions in transformer oil stressed by high voltage pulses, from which the dynamics of space charge development can be obtained. Correlation between space charge distribution pattern and impulse breakdown voltage is examined. Hypothetically, bipolar homo-charge injection with reduced electric field at both electrodes may allow higher voltage operation without insulation failure, since electrical breakdown usually initiates at the electrode-dielectric interfaces. It is shown that the hypothesis is testable and correct only under specific circumstances. Besides, fractal-like kinetics for electrode charge injection is identified from the measurement data, which enriches the knowledge on ionic conduction in liquids by offering an experimentally-determined boundary condition to the numerical model. Physical mechanisms based on formative steps of adsorption-reaction-desorption reveal possible connections between geometrical characteristics of electrode surfaces and fractal-like kinetics of charge injection. The second part of this thesis focuses on the fluctuations in the detected light intensity in Kerr measurements. Up to now, within an experimentally-determined valid range of high voltage pulse duration, the strategy to reduce fluctuation has been taking multiple measurements and then averaging the results. For very short impulses, it is found that the light intensities near the rough surfaces of electrodes both fluctuate in repeated measurements and vary spatially in a single measurement. The major cause is electrostriction which brings disturbances into optical detection. The calculated spatial variation has a strong nonlinear dependence on the applied voltage, which generates a precursory indicator of the electrical breakdown initiation. This result may have potential applications in non-destructive breakdown test and inclusion detection in dielectric liquids. When the applied voltage is dc or ac, signatures of turbulent electroconvection in transformer oil are identified from the Kerr measurement data. It is found that when the applied dc voltage is high enough, compared with the results in the absence of high voltage, the optical scintillation index and image entropy exhibit substantial enhancement and reduction respectively, which are interpreted as temporal and spatial signatures of turbulence. Under low-frequency ac high voltages, spectral and correlation analyses also indicate that there exist interacting flow and charge processes in the gap. This also clarifies the meaning of dc steady state and the requirement on ac modulation frequency in Kerr measurements.
by Xuewei Zhang.
Ph. D.
35
Althobaiti, Mohammed. "Characterization of high-κ dielectrics on germanium". Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/2009749/.
Pełny tekst źródłaStreszczenie:
This study explores and describes the interface properties of various high-k materials deposited on the Ge substrate. Deposition/ growth of these material films has been achieved using multiple techniques such as atomic layer deposition (ALD), molecular beam epitaxy and thermal growth. High dielectrics (k) materials based on metal (4d and 5d) such as Y2O3, ZrO2, HfO2, Ta2O5, and from the lanthanide series, La2O3 and Tm2O3 were deposited on germanium and characterized to find out interface quality and band offset between Ge substrate and the oxides. Additionally, Al2O3 was considered, both as an interface barrier layer and as a high –k layer. Material and interface characterization was done using atomic force microscopy (AFM), capacitance-voltage (C-V), current-voltage (I-V), Variable Angle Spectral Ellipsometry (VASE), X-Ray diffraction (XRD), and X-ray photoelectron Spectroscopy (XPS) including the post growth micro-structural and compositional analysis using high resolution transmission electron microscope (HRTEM). Various physical and electrical studies were performed based on the above mentioned characterization techniques. The high-k material/Ge interface has been studied systematically using XPS and VASE characterization, considering the effects of temperature and thickness during deposition. Two germanium interface engineering methods were developed and discussed: (i) germanate formation using La2O3 and Y2O3, and (ii) using Al2O3 and Tm2O3 as barrier layers, and S passivation for Ta2O5 films. Based on the physical and electrical characterization carried out in this work, Ge interface engineering using rare-earth material inclusion happens to be a promising route to fabricate Ge CMOS devices with high performance. This statement is supported by the fact that these high-k materials provide a defect free interface and reduce the possibility of unstable GeOx formation at the interface, hence improving the interface quality. Post deposition annealing effects on Tm2O3 has been analysed using XPS and VUV-VASE. The stack prepared for the purpose was of EOT (equivalent oxide thickness) ~5 nm Tm2O3/epi-Ge/Si. Study with Tm2O3 presented 3 main findings, i) Valence band offset estimation using Kraut’s method was consistent within the experimental error, and found to be 3.05 ± 0.2 eV, ii) the VBO for thermal GeO2/Ge stack was found to be matching with the recently reported value by Toriumi’s group. The value of conduction band offset was estimated to be higher than 1 eV, indicating the favorability of GeO2 as a passivation layer for Ge, iii) the reactivity of Tm2O3 on Ge was found to be even lower than that of Si, indicating the possibility of a desirable interface. This thesis further explores the use of hafnia and alumina with Sulphur (S) passivated and un-passivated Ge samples. For this purpose HfO2/Ge and Al2O3/Ge stacks were prepared using ALD technique. It was observed that using H2O with O plasma, reduces the purge time and gives low carbon incorporation from metals. Hence O plasma and H2O were used as oxidizing agents and the interface properties were studied systematically, which is a new contribution by this work. Further the effects of adding TiO2 contents to HfO2 layer on interface properties were studied, using Al2O3 (0.3 nm) as surface passivation. In this work the achieved EOT of HfO2 with the controlled introduction of TiO2 was ~ 1.3 nm, giving a leakage current as low as10-7 A/cm-2 at ±1 V, which is in the acceptable limits. Finally, Ta2O5 films were characterized on Ge for band line up with respect to Ge. The deposition of the films was done by ALD technique at 250 °C. The analysis was done on both S passivated and un-passivated samples. The band line up parameters were estimated using XPS and it was observed that the valence band offset for S passivated sample was 2.67 eV whereas it was 2.84 eV for un-passivated Ge sample. Ta2O5 reflected a band gap of 4.44 eV (estimated from the energy loss spectrum of O1 s core level) for a 20 nm thick film deposited by ALD. Hence this thesis will cover the high-k materials and their application as a gate oxide and also the passivation layer for Ge substrates for Ge CMOS devices.
36
Ali, Rizwan. "Resistive Switching in Porous Low-k Dielectrics". Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83462.
Pełny tekst źródłaStreszczenie:
Integrating nanometer-sized pores into low-k ILD films is one of the approaches to lower the RC signal delay and thus help sustain the continued scaling of microelectronic devices. While increasing porosity of porous dielectrics lowers the dielectric constant (k), it also creates many reliability and implementation issues. One of the problems is the little understood metal ion diffusion and drift in porous media. Here, we present a rigorous simulation method of Cu diffusion based on Master equation with elementary jump probabilities within the contiguous dielectric film, along the pore boundary, from the dielectric matrix to the pore boundary, and from the pore boundary to the matrix material. In view of the diffusional jump distance being as large as 2 nm, the nano-pores being on a similar length scale, and the film thickness being only a few tens of nanometers, the conventional diffusion equation in differential equation form is grossly inadequate and elementary jump frequencies are required for a proper description of the Cu diffusion in porous dielectric. The present atomistic approach allows a consistent implementation of Cu ion drift in electric field by lowering and raising of the diffusion barriers along the field direction. This will help understand the behavior of Cu interconnects under thermal or electric stress at an atomistic level.
Another approach to lower the increasing RC delays is to bring memory and logic closer by integrating memory in the BEOL. Resistive RAM is one such memory is not transistor based and thus, does not require a silicon substrate. Thus, it offers the possibility of integration directly into the back-end reducing memory to logic distance from 1000s of µm to a 10s of nm. This 3D integration also allows for increased density as well. However, one barrier in the implementation of RRAM in the back end is the use of expensive as well as non-BEOL native material in conventional Cu/TaOx/Pt resistive devices. In this thesis, we present our research about functionality of RRAM with porous low-k dielectrics (which are a candidate for CMOS ILD), and through the similar elementary jump simulations, discuss the impact of porosity in dielectrics on the functionality of RRAM. Lastly, we present a cheaper replacement for Pt as the counter electrode in RRAM and show that it functions as good as Pt.
This work addresses following three areas:
1. Modeling of diffusion in porous dielectrics through elementary jump based simulation. The model is based on random walk theory of elementary particle jumps. Initially, qualitative simulations are conducted without actual parameters. It is shown that Cu diffusion in porous dielectrics decreases quasi-linearly with porosity. Furthermore, it is shown that morphology of the pores may have a greater effect on diffusivity compared to porosity. The simulations are then calibrated with parameters, and the result is shown to yield a similar diffusivity times as actual process time.
2. Modeling of Cu ions drift in porous dielectrics under electric stress. First, the model is explained, and then qualitative simulation results are presented for porous dielectrics with varied porosities and morphologies.
3. Research to find a suitable replacement for Pt as the counter electrode in RRAM devices. The research methodology is discussed and a much cheaper Rh is selected as the potential replacement for Pt. Successful functionality of Rh based resistive devices is presented.Master of Science
37
Kramer, Bradley Allen. "Spiral antenna miniaturization with high-contrast dielectrics". The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1407225517.
Pełny tekst źródła
38
Dubov, Mykhaylo. "Direct femtosecond laser inscription in transparent dielectrics". Thesis, Aston University, 2011. http://publications.aston.ac.uk/18274/.
Pełny tekst źródłaStreszczenie:
Since 1996 direct femtosecond inscription in transparent dielectrics has become the subject of intensive research. This enabling technology significantly expands the technological boundaries for direct fabrication of 3D structures in a wide variety of materials. It allows modification of non-photosensitive materials, which opens the door to numerous practical applications. In this work we explored the direct femtosecond inscription of waveguides and demonstrated at least one order of magnitude enhancement in the most critical parameter - the induced contrast of the refractive index in a standard borosilicate optical glass. A record high induced refractive contrast of 2.5×10-2 is demonstrated. The waveguides fabricated possess one of the lowest losses, approaching level of Fresnel reflection losses at the glassair interface. High refractive index contrast allows the fabrication of curvilinear waveguides with low bend losses. We also demonstrated the optimisation of the inscription regimes in BK7 glass over a broad range of experimental parameters and observed a counter-intuitive increase of the induced refractive index contrast with increasing translation speed of a sample. Examples of inscription in a number of transparent dielectrics hosts using high repetition rate fs laser system (both glasses and crystals) are also presented. Sub-wavelength scale periodic inscription inside any material often demands supercritical propagation regimes, when pulse peak power is more than the critical power for selffocusing, sometimes several times higher than the critical power. For a sub-critical regime, when the pulse peak power is less than the critical power for self-focusing, we derive analytic expressions for Gaussian beam focusing in the presence of Kerr non-linearity as well as for a number of other beam shapes commonly used in experiments, including astigmatic and ring-shaped ones. In the part devoted to the fabrication of periodic structures, we report on recent development of our point-by-point method, demonstrating the shortest periodic perturbation created in the bulk of a pure fused silica sample, by using third harmonics (? =267 nm) of fundamental laser frequency (? =800 nm) and 1 kHz femtosecond laser system. To overcome the fundamental limitations of the point-by-point method we suggested and experimentally demonstrated the micro-holographic inscription method, which is based on using the combination of a diffractive optical element and standard micro-objectives. Sub-500 nm periodic structures with a much higher aspect ratio were demonstrated. From the applications point of view, we demonstrate examples of photonics devices by direct femtosecond fabrication method, including various vectorial bend-sensors fabricated in standard optical fibres, as well as a highly birefringent long-period gratings by direct modulation method. To address the intrinsic limitations of femtosecond inscription at very shallow depths we suggested the hybrid mask-less lithography method. The method is based on precision ablation of a thin metal layer deposited on the surface of the sample to create a mask. After that an ion-exchange process in the melt of Ag-containing salts allows quick and low-cost fabrication of shallow waveguides and other components of integrated optics. This approach covers the gap in direct fs inscription of shallow waveguide. Perspectives and future developments of direct femtosecond micro-fabrication are also discussed.
39
Branch, Greg. "Nonlinear pulsed power technology". Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386897.
Pełny tekst źródła
40
Afshar-Hanaii, Nasser. "Some aspects of submicron CMOS technology". Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358782.
Pełny tekst źródła
41
Espinosa, James Charles. "Dielectric breakdown of water /". Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004261.
Pełny tekst źródła
42
Ukirde, Vaishali. "Evaluation of hydrogen trapping in HfO2 high-κ dielectric thin films". Thesis, University of North Texas, 2006. https://digital.library.unt.edu/ark:/67531/metadc5596/.
Pełny tekst źródłaStreszczenie:
Hafnium based high-κ dielectrics are considered potential candidates to replace SiO2 or SiON as the gate dielectric in complementary metal oxide semiconductor (CMOS) devices. Hydrogen is one of the most significant elements in semiconductor technology because of its pervasiveness in various deposition and optimization processes of electronic structures. Therefore, it is important to understand the properties and behavior of hydrogen in semiconductors with the final aim of controlling and using hydrogen to improve electronic performance of electronic structures. Trap transformations under annealing treatments in hydrogen ambient normally involve passivation of traps at thermal SiO2/Si interfaces by hydrogen. High-κ dielectric films are believed to exhibit significantly higher charge trapping affinity than SiO2. In this thesis, study of hydrogen trapping in alternate gate dielectric candidates such as HfO2 during annealing in hydrogen ambient is presented. Rutherford backscattering spectroscopy (RBS), elastic recoil detection analysis (ERDA) and nuclear reaction analysis (NRA) were used to characterize these thin dielectric materials. It was demonstrated that hydrogen trapping in bulk HfO2 is significantly reduced for pre-oxidized HfO2 prior to forming gas anneals. This strong dependence on oxygen pre-processing is believed to be due to oxygen vacancies/deficiencies and hydrogen-carbon impurity complexes that originate from organic precursors used in chemical vapor depositions (CVD) of these dielectrics.
43
Rotaru, Andrei. "Novel polar dielectrics with the tetragonal tungsten bronze structure". Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/4184.
Pełny tekst źródłaStreszczenie:
There is great interest in the development of new polar dielectric ceramics and multiferroic materials with new and improved properties. A family of tetragonal tungsten bronze (TTB) relaxors of composition Ba₆M³⁺Nb₉O₃₀ (M³⁺ = Ga³⁺, Sc³⁺ and In³⁺, and also their solid solutions) were studied in an attempt to understand their dielectric properties to enable design of novel polar TTB materials. A combination of electrical measurements (dielectric and impedance spectroscopy) and powder diffraction (X-ray and neutron) studies as a function of temperature was employed for characterising the dynamic dipole response in these materials. The effect of B-site doping on fundamental dipolar relaxation parameters were investigated by independently fitting the dielectric permittivity to the Vogel-Fulcher (VF) model, and the dielectric loss to Universal Dielectric Response (UDR) and Arrhenius models. These studies showed an increase in the characteristic dipole freezing temperature (T[subscript(f)]) with increase B-cation radius. Crystallographic data indicated a corresponding maximum in tetragonal strain at T[subscript(f)], consistent with the slowing and eventual freezing of dipoles. In addition, the B1 crystallographic site was shown to be most active in terms of the dipolar response. A more in-depth analysis of the relaxor behaviour of these materials revealed that, with the stepwise increase in the ionic radius of the M³⁺ cation on the B-site within the Sc-In solid solution series, the Vogel-Fulcher curves (lnf vs. T[subscript(m)]) are displaced to higher temperatures, while the degree of relaxor behaviour (frequency dependence) increases. Unfortunately, additional features appear in the dielectric spectroscopy data, dramatically affecting the Vogel-Fulcher fitting parameters. A parametric study of the reproducibility of acquisition and analysis of dielectric data was therefore carried out. The applicability of the Vogel-Fulcher expression to fit dielectric permittivity data was investigated, from the simple unrestricted (“free”) fit to a wider range of imposed values for the VF relaxation parameters that fit with high accuracy the experimental data. The reproducibility of the dielectric data and the relaxation parameters obtained by VF fitting were shown to be highly sensitive to the thermal history of samples and also the conditions during dielectric data acquisition (i.e., heating/cooling rate). In contrast, UDR analysis of the dielectric loss data provided far more reproducible results, and to an extent was able to partially deconvolute the additional relaxation processes present in these materials. The exact nature of these additional relaxations is not yet fully understood. It was concluded application of the Vogel-Fulcher model should be undertaken with great care. The UDR model may represent a feasible alternative to the evaluation of fundamental relaxation parameters, and a step forward towards the understanding of the dielectric processes in tetragonal tungsten bronzes.
44
Quevedo-Lopez, Manuel Angel. "Materials properties of hafnium and zirconium silicates: Metal interdiffusion and dopant penetration studies". Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3221/.
Pełny tekst źródłaStreszczenie:
Hafnium and Zirconium based gate dielectrics are considered potential candidates to replace SiO2 or SiON as the gate dielectric in CMOS processing. Furthermore, the addition of nitrogen into this pseudo-binary alloy has been shown to improve their thermal stability, electrical properties, and reduce dopant penetration. Because CMOS processing requires high temperature anneals (up to 1050 °C), it is important to understand the diffusion properties of any metal associated with the gate dielectric in silicon at these temperatures. In addition, dopant penetration from the doped polysilicon gate into the Si channel at these temperatures must also be studied. Impurity outdiffusion (Hf, Zr) from the dielectric, or dopant (B, As, P) penetration through the dielectric into the channel region would likely result in deleterious effects upon the carrier mobility. In this dissertation extensive thermal stability studies of alternate gate dielectric candidates ZrSixOy and HfSixOy are presented. Dopant penetration studies from doped-polysilicon through HfSixOy and HfSixOyNz are also presented. Rutherford backscattering spectroscopy (RBS), heavy ion RBS (HI-RBS), x-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HR-TEM), and time of flight and dynamic secondary ion mass spectroscopy (ToF-SIMS, D-SIMS) methods were used to characterize these materials. The dopant diffusivity is calculated by modeling of the dopant profiles in the Si substrate. In this disseration is reported that Hf silicate films are more stable than Zr silicate films, from the metal interdiffusion point of view. On the other hand, dopant (B, As, and P) penetration is observed for HfSixOy films. However, the addition of nitrogen to the Hf - Si - O systems improves the dopant penetration properties of the resulting HfSixOyNz films.
45
Lupina, Grzegorz. "Praseodymium silicate high-k dielectrics on Si(001)". [S.l.] : [s.n.], 2006. http://se6.kobv.de:8000/btu/volltexte/2007/42.
Pełny tekst źródła
46
Hinkle, Christopher. "Fixed Charge Reduction and Tunneling in Stacked Dielectrics". NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-07252005-181136/.
Pełny tekst źródłaStreszczenie:
Stacked gate dielectrics using high-k materials were deposited using a RPECVD method. Aluminum oxide, hafnium oxide, hafnium silicate, nitrided films of each of the above, and multi-layer stacks of the above as well as silicon dioxide were deposited. These films were analyzed using AES, XPS, NRA, RBS, SIMS, XAS, cathodoluminescence, spectroscopic ellipsometry, capacitance-voltage, and current-voltage techniques. Fixed charge was found to be present in all high-k films and was practically impossible to reduce in a significant way. Nitridation of the films was unsuccessful at reducing the charge, but was helpful in enhancing some electrical measurements. Sandwich stack structures showed enhanced tunneling which led to a novel approach of calculating the Eb-meff product in the transmission probability equation. This tunneling also gives some clues as to which types of gate stacks cannot be used in technology. Gate stacks containing an HfO2 layer below an Al2O3 layer were studied and also showed enhanced tunneling. Analysis of this tunneling found two significant trapping sites in the HfO2 layer, one located ~0.5 eV below the HfO2 conduction band offset and the other located in the Si bandgap. Fixed charge reduction was again expected in these laminates, but again remained despite theoretical predictions.
47
Manepalli, Rahul Nagaraj. "Electron beam curing of thin film polymer dielectrics". Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/11036.
Pełny tekst źródła
48
Brownlee, Kellee Renee. "Evaluation of low stress dielectrics for board applications". Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/20040.
Pełny tekst źródła
49
Winkler, Thomas Torsten [Verfasser]. "Laser amplification in excited dielectrics / Thomas Torsten Winkler". Kassel : Universitätsbibliothek Kassel, 2018. http://d-nb.info/1155438558/34.
Pełny tekst źródła
50
Kennedy, Gary Paul. "Gate dielectrics for ULSI produced by plasma anodisation". Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240311.
Pełny tekst źródła