Scientists and engineers measure dielectric constant because it gives them better understanding of materials and helps them to know how to integrate these materials into their design processes;it also helps them to shorten design life cycle,and aside these two functions,it has numerous uses all of which cannot be enumerated in this section.Owing to its usefulness,various measurement methods of dielectric constant of materials have been developed over the years.Each method has its limitations which affect the accuracy of the measurement;these limitations range from frequency,temperature,and  mearsurement environment to material under test.   In this thesis,four most common methods of measuring dielectric constant were discussed and the most accurate one,the resonant method,was chosen and worked on .The project was executed by making a mathematical analysis of the ring resonator which was later simulated in HFSS to get results which would be comparable to ones obtained in  laboratory measurements.   The ring was fabricated and taken to the laboratory for measurement.Two monopole antennas were connected to the two ports of a VNA with one antenna serving as the transmitter and the other serving as the receiver.   The resonant frequencies obtained were combined with the geometric parameters of the ring resonator and that of the MUT in equations written into MATLAB scripts;this equations were used to extract the dielectric constant of the MUT.

The key features of dynamics of ultraslowing glass forming systems are their universality in diversity. Its origin is recognized as one of the greatest challenges of condensed matter physics and materials engineering in the XXI century. Similar phenomena are observed on approaching the glass transition in low molecular weight supercooled liquids, polymers, colloidal fluids as well as in solids, for instance in orientationally disordered crystals, spin glass-like magnetic, vortex glasses. Pre-vitreous dynamics is also proposed as a general reference for the category of complex liquids/soft matter systems. The upsurge of the primary relaxation time or related dynamical properties is the basic physical phenomena of the still mysterious previtreous behavior. This means a much more pronounced slowing down than the Arrhenius pattern observed far above the glass transition temperature. Portraying this behavior constitutes one of key checkpoints for theoretical models developed to unwind the glass transition puzzle. However, none of the aforementioned features can answer the understanding that governs the increase of relaxation time in liquids upon cooling. In this thesis we focus on the above questions studying the dynamics of some materials for which their molecules can retain a translational order being orientationally disordered between them upon cooling, which are referred to plastic phases or orientationally disordered (OD) crystalline phases. The work presented in this thesis potentially extends the knowledge of dynamics of OD phases and orientationally glasses (OG), a research topic which has gained interest during the last decades. Through this study, especial attention has been devoted to the phenomenological equations accounting to the temperature dependence of the mean relaxation time describing the orientational dynamics .The study was carried out by the use of BDS as well as two complementary experimental techniques. We show distortion-sensitive and derivative-based empirical analysis of the validity of leading equations for portraying the previtreous evolution of primary relaxation time. A new method for studying the dynamics of glass forming systems is introduced and the minimization procedure is validated and discussed. We present the results divided in two topics, the dynamics of the pure compounds and mixed crystals and the derivative analysis through different existing models. In the first topic we focus on the dynamics of the pure compounds and mixed crystals formed between cycloheptanol and cyclooctanol as well as the a-relaxation dynamics of 1-cyano-adamantane and its mixtures with 1-chloro-adamantane. The second topic is divided in two groups of models, linearized and non-linearized models. In the linearized models we show the application of the derivative based, distortion-sensitive analysis to liquid crystals (LC) and OD phases. We also discuss the results concerning to the cases of the olygomeric liquid epoxy resin (EPON828), neopentylalcohol and neopentylglycol mixture, isooctylcyanobiphenyl and propylene carbonate. The possible empirical correlations between one of the linearized models with the universal pattern for the high frequency wing of the loss curve for primary relaxation time for LCs and OD phases is also shown. In the final part we show that the form of the equation recently introduced by Mauro et al. does not allow a similar straightforward linearization procedure. Unlike the previous models, the involved parameters are not correlated with the slope and the intercept of a linear function. In order to solve this problem, we have introduced the concept of the enthalpy space. The evidences of the existence of crossovers as well as quantitative descriptions are discussed. We show also a new procedure for detecting the crossover in a very easy way. A new kind of crossovers which seems to be impossible to be detected by the classical Stickel transformation is presented. / La principal característica de la dinámica de sistemas vítreos viscosos, es su universalidad en la diversidad. Su origen es uno de los mayores desafíos de la física de la materia condensada y de la ingeniería de materiales en el siglo XXI. La fenomenología típica de las fases vítreas se observan cerca de la transición vítrea en líquidos subenfriados de bajo peso molecular, polímeros, fluidos coloidales, así como en los sólidos con fases orientacionalmente desordenadas. La imposibilidad de explicar las causas del gran aumento del tiempo de relajación al enfriar un líquido, constituye uno de los problemas más importantes no resueltos en materia condensada. Con el objetivo de dar respuesta a dicha interrogante, se han propuesto modelos termodinámicos y dinámicos que han resultado inconsistentes. En esta tesis nos centramos en dicha problemática, estudiando la dinámica orientacional de algunos materiales que al ser enfriados pueden conservar un orden traslacional mientras que se conserva el desorden orientacional de las moléculas que los forman. Dichas fases se conocen como fases plásticas u orientacionalmente desordenadas (OD). El trabajo presentado en esta tesis amplía el conocimiento de la dinámica de dichas fases, un tema de investigación cuyo interés ha aumentado durante las últimas décadas. Se ha dedicado una atención especial a las ecuaciones fenomenológicas que describen la dependencia del tiempo de relajación con la temperatura. El estudio se ha llevado a cabo mediante el uso de espectroscopía dieléctrica de banda ancha, así como mediante el uso de técnicas experimentales complementarias. Se ha introducido un nuevo método para el estudio de la dinámica de los sistemas que dan lugar a fases vítreas. El método ha sido validado y discutido. Los resultados de esta tesis se presentan divididos en dos temas, por un lado, la dinámica de compuestos puros y de los cristales mixtos y, por otro, el análisis mediante el método derivativo aplicado a los diferentes modelos físicos existentes. En el primer tema nos centramos en la dinámica de los compuestos puros y los cristales mixtos formados por cicloheptanol y ciclooctanol, así como la dinámica de la relajación alfa en 1-ciano-adamantano y sus mezclas con 1-cloro-adamantano. El segundo tema se divide en dos grupos de modelos, los modelos lineales y no lineales. En los modelos lineales se muestra la aplicación del procedimiento de derivativo en los cristales líquidos (CL) y las fases OD. También se discuten los resultados relativos a los casos de la resina líquida (EPON828), la mezcla neopentil-alcohol y neopentil-glicol, el carbonato de propileno, así como el CL isooctilcianobifenil. Se discute también la existencia de posibles correlaciones empíricas entre uno de los modelos lineales con el patrón universal para la parte de alta frecuencia de la curva de pérdidas dieléctricas de la relajación primaria para las fases CL y OD. En la parte final se muestra que la forma de la ecuación introducida recientemente por Mauro et al. no permite la linearización mediante el método derivativo. A diferencia de los modelos anteriores, los diferentes parámetros no están correlacionados con la pendiente y el origen de coordenadas de una función lineal. Para resolver este problema, hemos introducido el concepto del espacio entálpico. Se analiza también la existencia de cambios de comportamiento dinámicos y se aportan descripciones cuantitativas. Se muestra también un nuevo procedimiento para detectar los cambios dinámicos de una manera fácil, que permite incluso detectar aquéllos que son obviados mediante el método clásico de Stickel.

Ever-increasing interest in millimeter-wave and terahertz spectrum has prompted research and development of novel passive components working at these frequencies. Compared with the conventional planar components, non-planar dielectric devices become more attractive as frequencies increase due to their higher quality factors and dimensional tolerances. In this thesis, we present fast methods to analyze the millimeter-wave dielectric resonator and rod antenna. First, an analytical method has been developed to evaluate resonant frequencies, quality factors of the Whispering Gallery Mode (WGM) disk resonators and also the resonator-waveguide coupling. A numerical solver based on full-wave finite element method is implemented to verify the analytical result. This analytical model provides a solution for fast design and optimization of WGM resonators in filter and sensor applications. Secondly, a fast analytical approach based on local mode theory is introduced to calculate the radiation from tapered dielectric rod antenna. This efficient approximate model consumes much less computing resources and time, and demonstrates good agreements with full-wave numerical results. It supplies a quantitative way to understand the radiation mechanism and interaction between different parts of the antenna. Based on this, design criteria for the taper profile of rod antennas are given.

In microwave communications, the main aspects for affecting the dielectric losses in the materials are relating to the dielectric properties and the radiation frequencies. Normally, the different dielectric materials will lead to the different losses and reflections for microwave frequencies. To evaluate the dielectric properties from the different materials plays an essential role in the microwave engineering. There are many approaches can be used to measure the dielectric materials, e.g. capacitor methods, transmission line methods, cavity resonator methods, open cavity methods and so on. The cavity resonator method is one of the most popular ways for measuring the dielectric materials. In this thesis, some of the techniques will be reviewed, and the TM010 mode cylindrical cavity resonator with perturbation technique will be used for determining the dielectric properties. The design and measurements will be presented in both simulations and practice. With 1.2GHz cavity resonator, in the simulations, the dielectric permittivity for Teflon is measured as 2.09-0.0023i and 2.12-0.0116 in copper cavity and ferromagnetic cavity. Finally the sample is measured as 3.83-0.12i in practice.

HfO2 is a popular replacement for SiO2 in modern CMOS technology. It is used as the gate dielectric layer isolating the transistor channel from the gate. For this application, certain material property demands need to be met, most importantly, a high static dielectric constant is desirable as this positively influences the effectiveness and reliability of the device. Previous theoretical calculations have found that this property varies with the crystal structure of HfO2; specifically, the tetragonal structure possesses the highest dielectric constant (~70 from theoretical calculations) out of all possible stable structures at atmospheric pressure, with the cubic phase a far second (~29, also calculated). Following the results from previous experimental work on the phase formation of sputtered HfO2, this study investigates the possibility of producing thin films of HfO2 with the cubic or tetragonal structure by the addition of nitrogen to a reactive sputtering process at various deposition temperatures. Also, a new physical vapor deposition method known as High Power Impulse Magnetron Sputtering (HiPIMS) is employed for its reported deposition stability in the transition zone of metal-oxide compounds and increased deposition rate. Structural characterization of the produced films shows that films deposited at room temperature with a low N content (~6 at%) are mainly composed of amorphous HfO2 with mixed crystallization into t-HfO2 and c-HfO2, while pure HfO2 is found to be composed of amorphous HfO2 with signs of crystallization into m-HfO2. At 400o C deposition temperature, the crystalline quality is enhanced and the structure of N incorporated HfO2 is found to be c-HfO2 only, due to further ordering of atoms in the crystal lattice. Optical and dielectric characterization revealed films with low N incorporation (< 6 at%) to be insulating while these became conductive for higher N contents. For the insulating films, a trend of increasing static dielectric constant with increasing N incorporation is found.

Ever-increasing interest in millimeter-wave and terahertz spectrum has prompted research and development of novel passive components working at these frequencies. Compared with the conventional planar components, non-planar dielectric devices become more attractive as frequencies increase due to their higher quality factors and dimensional tolerances. In this thesis, we present fast methods to analyze the millimeter-wave dielectric resonator and rod antenna. First, an analytical method has been developed to evaluate resonant frequencies, quality factors of the Whispering Gallery Mode (WGM) disk resonators and also the resonator-waveguide coupling. A numerical solver based on full-wave finite element method is implemented to verify the analytical result. This analytical model provides a solution for fast design and optimization of WGM resonators in filter and sensor applications. Secondly, a fast analytical approach based on local mode theory is introduced to calculate the radiation from tapered dielectric rod antenna. This efficient approximate model consumes much less computing resources and time, and demonstrates good agreements with full-wave numerical results. It supplies a quantitative way to understand the radiation mechanism and interaction between different parts of the antenna. Based on this, design criteria for the taper profile of rod antennas are given.

No description available.

High performance miniaturized passives are of great importance for advanced nanoelectronic packages for several applications including efficient power delivery. Low cost thin film capacitors fabricated directly on package (and/or on-chip) are an attractive approach towards realizing such devices. This thesis aims to explore fundamental frequency dependent dielectric and insulating properties of thin film high-k dielectric constant in the perovskite and perovskite-related complex oxides. Throughout this thesis, we have successfully observed the role of structure, strain and oxygen stoichiometry on the dielectric properties of thin film complex oxides, allowing a greater understanding of processing conditions and polarization mechanisms. In the first section of the thesis, we explore novel processing methods in the conventional ferroelectric, barium strontium titanate, \(Ba_{1-x}Sr_xTiO_3 (BST)\), using ultraviolet enhanced oxidation techniques in order to achieve improvements in the dielectric properties. Using this method, we also explore the growth of BST on inexpensive non-noble metals such as Ni which presents technical challenges due to the ability to oxidize at high temperatures. We observe a significant lowering of the dielectric loss while also lowering the process temperature which allows us to maintain an intimate interface between the dielectric layer and the metal electrode. The second section of this thesis explores the novel dielectric material, Lanthanum Strontium Nickelate, \(La_{2-x}Sr_xNiO_4 (LSNO)\), which exhibits a colossal dielectric response. For the first time, we report on the colossal dielectric properties of polycrystalline and epitaxial thin film LSNO. We observe a significant polarization dependence on the microstructure due to the grain/grain boundary interaction with charged carriers. We next grew epitaxial films on various insulating oxide substrates in order to decouple the grain boundary interaction. Here we observed substrate dependent dielectric properties associated with induced strain. We also observe, due to the p-type carriers in LSNO, pn junction formation when grown epitaxially on the conducting oxide degenerate n-type Nb-doped \(SrTiO_3\). Finally we explore the growth mechanism of epitaxial LSNO as a function of high oxygen content. Due to the ability for LSNO to take in interstitial oxygen, a reoriented growth is observed at a critical thickness, thereby allowing us to vary anisotropy as a function of deposition conditions. / Engineering and Applied Sciences

Driven by ever growing demands of miniaturization, increased functionality, high performance and low cost for microelectronic products and packaging, embedded passives will be one of the key emerging techniques for realizing the system integration which offer various advantages over traditional discrete components. Novel materials for embedded capacitor applications are in great demand, for which a high dielectric constant (k), low dielectric loss and process compatibility with printed circuit boards are the most important prerequisites. To date, no available material satisfies all these prerequisites and research is needed to develop materials for embedded capacitor applications. Conductive filler/polymer composites are likely candidate material because they show a dramatic increase in their dielectric constant close to the percolation threshold. One of the major hurdles for this type of high-k composites is the high dielectric loss inherent in these systems. In this research, material and process innovations were explored to design and develop conductive filler/polymer nanocomposites based on nanoparticles with controlled parameters to fulfill the balance between sufficiently high-k and low dielectric loss, which satisfied the requirements for embedded decoupling capacitor applications. This work involved the synthesis of the metal nanoparticles with different parameters including size, size distribution, aggregation and surface properties, and an investigation on how these varied parameters impact the dielectric properties of the high-k nanocomposites incorporated with these metal nanoparticles. The dielectric behaviors of the nanocomposites were studied systematically over a range of frequencies to determine the dependence of dielectric constant, dielectric loss tangent and dielectric strength on these parameters.

Thesis (M.S.)--Rochester Institute of Technology, 2006. / Typescript. Includes bibliographical references (leaves 145-146).