Dissertations / Theses on the topic 'Dielectric Applications'

One of the great challenges in optics is to break the diffraction limit to achieve optical superresolution for applications in imaging, sensing, manufacturing and characterization. In recent years we witnessed a number of exciting developments in this field, including for example super-resolution fluorescent microscopy, negative-index metamaterial superlens and superoscillation lens. However, none of them can perform white-light super-resolution imaging until the development of microsphere nanoscopy technique, which was pioneered by the current PhD’s research group. The microscope nanoscopy technique was developed based on all-dielectric microsphere superlens which is fundamentally different from metal-based superlenses. In this research, we aim to significantly advance the technology by: (1) increasing superlens resolution to sub- 50 nm scale and (2) improving superlens usability and demonstrate application in wider context including lab-on-chip devices. Our longer-term vision is to bring the all-dielectric superlens technology to market so that each microscope user can have superlens in hand for their daily examination of nanoscale objects including viruses. To improve the superlens resolution, a systematic theoretical study was first carried out on the optical properties of dielectric microsphere superlens. New approaches were proposed to obtain precise control of the focusing properties of the microsphere lens. Using pupil mask engineering and two-material composite superlens design, one can precisely control the focusing properties of the lens and effectively surpass the diffraction limit λ/2n. To further improve the resolution, we incorporated the metamaterial concept in our superlens design. A new all-dielectric nanoparticle metamaterial superlens design was proposed. This is realized by 3D stacking of high-index nanoparticles to form a micro-sized particle lens. This man-made superlens has unusual optical properties not found in nature: highly effective conversion of evanescent wave to propagating wave for unprecedented optical super-resolution. By using 15 nm TiO2 nanoparticles as building blocks, the fabricated 3D all-dielectric metamaterial-based solid immersion lens (mSIL) can produce a sharp image with a super-resolution of at least 45 nm under a white-light optical microscope, significantly exceeding the classical diffraction limit and previous near-field imaging techniques. In additional to mSIL where only one kind of nanoparticle was used, we also studied twoVII nanomaterial hybrid system. High-quality microspheres consisting of ZrO2/polystyrene elements were synthesised and studied. We show precise tuning of the refractive index of microspheres can effectively enhance the imaging resolution and quality. To increase superlens usability and application scope, we proposed and demonstrated a new microscope objective lens that features a two times resolution improvement over conventional objective. This is accomplished by integrating a conventional microscope objective lens with a superlensing microsphere lens with a customised lens adaptor. The new objective lens was successfully demonstrated for label-free super-resolution static and scanning imaging of 100 nm features in engineering and biological samples. In an effort to reduce superlens technology entrance barrier, we studied several spider silks as naturally occurring optical superlens. These spider silks are transparent in nature and have micron-scale cylinder structure. They can distinctly resolve λ/6 features with a large field-of-view under a conventional white-light microscope. This discovery opens a new door to develop biology-based optical systems and has enriched the superlens category. Because microsphere superlenses are small in size, their application can be extended to lab-on-chip device. In this thesis, microsphere superlens was introduced to a microfluidic channel to build an on-chip microfluidic superlensing device for real-time high-resolution imaging of biological objects. Several biological samples with different features in size, transparency, low contrast and strong mobility have been visualised. This integrated device provides a new way to allow researchers to directly visualise details of biological specimens in real-time under a conventional white light microscope. The work carried out in this research has significantly improved the microsphere superlens technology which opens the door for commercial exploitation.

This thesis describes my work on manufacturing of all dielectric polymer/ceramic composites for electromagnetic property customisation at microwave frequencies. Electromagnetic wave manipulation can be achieved with the help of transformation optics concept and metamaterials with desired permittivity and permeability properties. The use of all-dielectric metamaterials, in particular, offers a novel solution to broadband, low loss microwave devices. In this work, polymer/ceramic composites were studied to provide materials with a wide range of permittivity that can be customised precisely by optimised manufacturing routes. Thermoplastic perfluoroalkoxy (PFA) and thermoset epoxy were mainly used as polymer matrices and ferroelectric powders such as barium titanate used as ceramic fillers. Different composite types were fabricated by spraying, casting and 3D printing, with each manufacturing method carefully studied to produce stable and uniform composite quality. The microstrcutures of these composites were examined by microtomy and SEM and the dielectric properties were assessed by impedance and waveguide measurements for difference microwave frequency ranges. Controllable dielectric constants from 3 to 18 with high accuracy in epoxy/BT composites were achieved at 12 - 18 GHz. These composites were then used to fabricate advanced microwave devices such as the power divider lens to demonstrate my capability of permittivity customisation. Simulations for these advanced applications were done in Comsol Multiphysics and were compared to the experimental results.

Dielectric thin films have a long history in silicon photovoltaics. Due to the specific physical properties, they can function as passivation layer in solar cells. Also, they can be used as antireflection coating layers on top of the devices. They can improve the back surface reflectance if proper dielectric layers combination is used. What??s more, they can protect areas by masking during chemical etching, diffusion, metallization among the whole fabrication process. Crystalline silicon solar cell can be passivated by two ways: one is to deposit dielectric thin films to saturate the dangling bonds; the other is to introduce surface electrical field and repel back the minority carriers. This thesis explores thermally grown SiO2 and sputtered Si3N4(:H) to passivate n-type and thermal evaporation AlF3 to passivate p-type Float Zone silicon wafers, respectively. Sputtering is a cheap passivation method to replace PECVD in industry usage, but all sputtered samples are more likely to have encountered surface damage from neutral Ar and secondary electrons, both coming from the sputtered target. AlF3/SiO2 multi-layer stack is a negative charge combination; p inversion layer will form on the wafer surface. Light trapping is an important part in solar cell research work. In order to enhance the reflectance and improve the absorption possibility of near infrared photons, especially for high efficiency PERL cell application, the back surface structure is optimized in this work. Results show SiO2/Ag is a very good choice to replace SiO2/Al back reflectors. The maximum back surface reflectance is 97.82%. At the same time, SiO2/Ag has excellent internal angle dependence of reflectance, which is beneficial for surface textured cells. A ZnS/MgF2/SiO2/Al(Ag) superlattice can improve the back reflectance, but it is sensitive to incident angle inside the silicon wafer. If planar wafers are used to investigate all kinds of back reflectors, and an 8 degrees incident angle is fixed for typical spectrometry measurement, the results are easy to predict by Wvase software simulation. If a textured surface is considered, the light path inside the silicon wafer is very complicated and hard to calculate and simulate. The best way to evaluate the result is through experiment.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2003.
Includes bibliographical references (p. 175-183).
The semiconductor industry is currently faced with the problem of the use and emissions of strong global warming compounds, known as perfluorocompounds (PFCs) for dielectric etch applications. The release of global warming compounds from this and other sources is suspected to result in changes in the earth's climate and weather patterns. Quantitative targets for emissions reduction set by the World Semiconductor Council (WSC) makes it urgent to find a solution to this issue. A long-term means of approaching this problem is to find and develop alternative chemistries that are more environmentally benign without sacrificing performance. Several classes of chemistries have been investigated to date, including hydrofluorocarbons (HFCs), iodofluorocarbons (IFCs), and NF3/hydrocarbons. One class of chemistries that have shown considerable promise is the unsaturated fluorocarbons (UFCs). The research documented herein uses the UFCs to assess etch process and emissions performance. Not only are these novel chemistries tested on conventional silicon dioxide films, but also on new low-k dielectrics that are likely candidates for future generation process flows. Emissions and process performance are reported for each of the different gases. The prospects for integration of some of these chemistries to next generation processes are good from both a process and emissions standpoint. The UFCs are not strong greenhouse gases as a result of their short atmospheric lifetimes (typically less than a day). Unlike many of the previous alternative chemistries studied, the emissions from UFCs are due to reformation of reactive products into strong global warming gases, specifically PFCs and HFCs, in the plasma environment. In this work, the formation of plasma effluents has been studied.
(cont.) In this work, the formation of plasma effluents has been studied. These reformation products are not only a result of the reformation of reactive species from the breakup of the feed gas, but also a result of the interaction of the plasma with surfaces in the etch chamber, including the wafer being etched. Process performance has been assessed by performing cross-sectional scanning electron microscopy (SEM). Emissions data have been collected using Fourier transform infrared spectroscopy (FTIR). In-situ process monitoring methods such as optical emission spectroscopy (OES) and residual gas analysis (RGA) have been used in some experiments. Ex-situ studies of fluorocarbon deposited films have been performed using X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (TOF-SIMS). Screening experiments performed on an Applied Materials HDP high-density etch chamber showed that all of the UFCs in addition to a fluorinated ether were capable of process performance comparable to PFC based processes, such as C3F8. These studies showed that octafluorocyclopentene and hexafluoropropene processes result in greater than 70% emissions reduction compared to a C3F8-based reference process. Three isomers of C4F6 performed even better, with greater than 80% emissions reduction. Hexafluorobenzene based processes displayed the greatest silicon dioxide etch emissions reduction of 97% ...
by Ritwik Chatterjee.
Ph.D.

Transition metal Dichalcogenide MoS2in the monolayer and few-layer form have generated intense interest in the fundamental and applied research community due to its surprisingly strong light-matter interactions, strong excitonic effect, and unique elec-tronic and chemical activity at the edges. In this thesis work, I have conducted a series of synergistic experimental and computational investigations focused on understanding the fundamental optical properties of few-layer MoS2(experiment with supporting computational calculations) and its potential application into the electrochemical reduction of CO2(computational)In the first part of the thesis, I show that sulfur vacancies affect the optical properties of few-layer thin films deposited using magnetron sputtering. In particular, I show that sulfur vacancies can obscure the well-defined A/B excitons in MoS2. Next, while contributing with the process of developing high-quality MoS2films, I designed an approach to accurately determine the optical constants by combining transmission spectroscopy with spectroscopic ellipsometry. The method, which we call Transmission-assisted spectroscopic ellipsometry (TASE), is demonstrated on high-quality MoS2films deposited on transparent and absorbing substrates. Next, Transmission spectroscopy combined with the Kramers-Kronig consistent optical model was employed to determine the complex dielectric function of few-layer MoS2in the broadband energy range of 0.7-6.5 eV. Optical transitions leading to peaks in the dielectric functions are assigned to the band structure. In particular, a new peak is observed and assigned at 4.5 eV in few-layer MoS2. Finally, I have examined the effectiveness of doped MoS2on the catalytic activity for CO reduction using density functional theory method. The structural calculation shows that doping Mo edge site of MoS2with transition metals that have higher work function than Mo atom results a lowering in the CO adsorption energy which suppresses the dissociation reaction and enhances the hydrogenation reaction. The Bader charge analysis shows that the dopant atom does not contribute to CO adsorption directly but it reduces the charge density at the edge atom that is indicated from the Density of states.

Thesis (Ph.D)--Materials Science and Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Wong, C. P.; Committee Member: Jacob, Karl; Committee Member: Liu, M. L.; Committee Member: Tannenbaum, Rina; Committee Member: Wang, Z. L.. Part of the SMARTech Electronic Thesis and Dissertation Collection.

This thesis develops dielectric theory in multilayers and following cases have been considered: - Normal incidence on a multilayered slab with n isotropic layers. - Parallel incidence on a multilayered slab with n isotropic layers. - Normal and parallel incidence on a multilayered with n anisotropic layers, analysed in the non-retarded limit. In each case we have developed the appropriate transfer matrix recurrence relation and solved it exactly, using computer algebra (REDUCE and MATHEMATICA) as an essential guide. For all the problems listed above, we have obtained closed form solutions for the dispersion relations of surface and interface plasmons and for the angle-resolved energy-loss function. The energyloss spectrum is then obtained by integrating over wavevectors. The formulas we have derived are applied to real materials such as Al/Mg, Al/Al203, Al/Si02/Si, diamond and graphite.

Structure-property relationships in various 12- and IS-layer hexagonal perovskites have been investigated for use in Microwave Dielectric (MD) applications. Specifically; (i) the structural origin(s) of a peak in Er at 465 K for the 12-layer hexagonal perovskite Ba3LaNb3012, BLN, and its effect on the Temperature Coefficient of resonant Frequency, TCF; (ii) synthesis and structure-property relationships of related 12-layer hexagonal perovskites based on Ba3RENb)012 and Sr)RENbJOI2 with RE ions smaller than La3+ ; (iii) a study of the IS-layer hexagonal perovskite solid solution phase (Bas-xSrx)Nb4015 to establish if similar properties to BLN can be obtained and therefore improve our understanding of how octahedral tilting in hexagonal perovskites influences their microwave dielectric properties. (i) A study of the BLN crystal structure using mode analysis of Neutron Powder Diffraction, NPD data showed the structure to go from one with a tilted NbOIi network (space group RI) at 300 K to un-tilted (space group RIm) at 500 K. On cooling, the change in Nb06 framework at - 500 K causes displacement of the A-site cations from their ideal positions within the AO .• layers at - 465 K; it is this movement of A-site cations in response to octahedral tilting that gives rise to the peak in Er. Raman Spectroscopy, RS showed the loss of a peak (- 425 cm -I) at - 400 K that is associated with the phase transition. (ii) Ba,RENbJOl2 with RE = Pr3+ or Nd3+ did not exhibit resonance at microwave frequencies. Instead a relaxor-type response was observed from radio frequency measurements with a maximum in I::r near or below room temperature. NPD and RS data showed this behaviour is linked to size mismatch (cation variance) between the A-site cations. Sr3PrNb3012 showed encouraging microwave dielectric properties with I::r - 35, Q.f - 17,000 GHz and TCF - 8 ppm K-'. (iii) The (Bas_xSrx)Nb4015 study found materials that do show similar properties to BLN. Sr-rich members of this study vi can be described has having a tilted NbOf, network (space group PJe!) whereas the Ba- rich members contain untilted Nb06 octahedra (space group PJmJ) at room temperature. This change from a tilted to untilted structure as the Ba content increases leads to a crossover from a tilt to untilt system at room temperature for Ba2:;Sr2.sNb4015 (B2.5S2SNO). This crossover at B2.5S2.sNO is reflected in the room temperature er and TCF (Er - 47, TCF - 343 ppm K-1) which have their highest values for this composition. This provides confirmation of the effect octahedral tilting can have on MD properties. The trend in Q.f is obscured by extrinsic effects, for example as a result of an irregular ceramic microstructure (SrsNb40ls) and the presence of impurities that exist as intergrowths within the main phase. The analysis of the FWHM of M" Debye peaks from IS data was useful to detect electrical heterogeneity within the grains and could be used to link with Q.f. vii

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.
Includes bibliographical references.
The removal of dielectric films in semiconductor processing relies almost exclusively on the use of perfluorocompounds (PFCs), which are suspected global warming agents. The two applications in semiconductor manufacture that account for the largest use and emissions of PFCs are the patterning of dielectric films and the cleaning of dielectric film plasma enhanced chemical vapor deposition (PECVD) chambers. The work discussed in the author's Ph.D. thesis was conducted as part of a project whose goal is to identify and develop novel replacement etchants for these applications. The focus of the author's Ph.D. thesis is the patterning application. The research discussed in this document constitutes a follow up to the author's M.S. thesis, which discussed the initial stages of this project. These stages consisted primarily of preliminary screening tests involving a class of chemistries which was expected to be promising from a process standpoint at an early point in the project. The work carried out subsequently covered a far greater scope of activities and included additional preliminary screening tests with chemistries that were not covered by the author's M.S. thesis as well as extensive concept-and-feasibility tests and subsequent process development efforts using several of the more promising chemistries in a dielectric wafer patterning application. Much of this experimental work had been carried out in collaboration with industrial partners belonging to the semiconductor manufacturer, equipment supplier, and gas supplier communities. These tests were carried out on process tools housed both within MTL's Integrated Circuits Laboratory and at an industrial location, namely Motorola Inc.'s Advanced Products Research and Development Laboratory (APRDL). The project to identify and develop alternative chemistries for dielectric film removal applications is continuing after the completion of the author's thesis, with subsequent studies that will build on the results of the work done to date. The research presented in this document involved the evaluation of fluorinated compounds belonging to three principal families of modified fluorocarbon molecules: hydrofluorocarbons (HFCs), iodofluorocarbons (IFCs), and unsaturated fluorocarbons (UFCs). In addition, other chemistries, namely trifluoroacetic anhydride (TFAA), oxalyl fluoride, and octafluorotetrahydrofuran, were also examined. The focus of much of the work was on the etching of patterned silicon oxide films in back-end-of-the-line (BEOL) applications such as via etch. In its mature phases, the work conducted relied on a two pronged approach toward evaluating new etchants: characterization of their process performance and characterization of their process emissions prior to release into the atmosphere. Cross-sectional scanning electron microscopy (SEM) was the principal means of process performance characterization, whereas Fourier transform infrared (FTIR) spectroscopy was the principal technique employed for effluent characterization. At appropriate times, other diagnostic techniques, namely x-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), Auger electron spectroscopy (AES), and quadrupole mass spectrometry (QMS) were also used for film or effluent characterization. Within the HFC family, candidates were identified that exhibited generally good process results with emissions reductions ranging from -40% into the 70% range relative to a PFC based reference. More comprehensive tests with IFC compounds demonstrated that emissions reductions in the 80% range are attainable for working processes. Good performance was obtained with respect to some, but not all, key process metrics, demonstrating the potential utility of IFCs in certain dielectric etch applications, but also indicating that there were significant limitations to their use, stemming mostly from selectivity problems. In tests with UFC compounds, emissions reductions on the order of 85%, combined with good process performance, were obtained. This family of compounds showed the greatest promise from both an emissions standpoint and a process standpoint. In particular, compounds in this family showed very good mask layer and stop layer selectivity, in addition to good etch rates and good profile control. It is particularly encouraging that the use of some of these compounds, in addition to offering emissions reductions, may, in fact, offer a process advantage over conventional chemistries in applications requiring high selectivity. At the time of this writing, unsaturated fluorocarbons are viewed as a major avenue for further exploration within the ongoing PFC alternatives project.
by Simon Martin Karecki.
Ph.D.

This thesis presents the results of research into the performance of advanced polymer dielectrics for the realization of high-power electronic circuits in a miniature form. These polymeric materials must satisfy a number of critical thermal, environmental, and electrical requirements to meet the required performance criteria for microelectronics applications. These desired attributes include thermal stability, low moisture uptake, high breakdown voltage (low leakage current), low dielectric constant, low loss tangent, high glass transition temperature, and low surface roughness. The use of these polymers allows for advanced electronic packaging techniques, resulting in improved system performance and reliability. Research was performed using a commercially available polymer dielectric and evaluated the feasibility of utilizing these materials as interlayer dielectrics in multilayer power electronic circuits. Historically, efforts to develop advanced interlayer dielectric materials have concentrated on promoting their use in high speed digital circuits. However, dielectrics used in power electronics must meet requirements not commonly stressed in designs for digital circuits. Multilayer circuits used in power electronics place a particular emphasis on the material properties of high dielectric strength or breakdown voltage and small values for loss tangent or dissipation factor. The focus of this research has been to characterize these particular properties for a commercially available polymer dielectric.
Master of Science

This study was designed to develop some predictive models for the dielectric properties of the chemicals and chemical reactions and make use of dielectric properties and microwave irradiation in the chemical reactions. Specifically, the dielectric properties of the following systems were investigated at microwave frequencies of 2450 and 915 MHz: (1) C1--C5 alcohols, (2) glucose aqueous solutions, (3) lysine aqueous solutions, (4) mimicked esterification reaction model systems of parahydroxybenzoic acid with methanol, 1-propanol and 1-butanol in the presence of para-toluene sulfonic acid as a catalyst, (5) Maillard reaction model system consisting of glucose, lysine and water.
The dielectric properties of the model systems showed that they depended on the frequency applied, concentration of the material, and temperature. Most of the predictive models showed that there exists a linear or quadratic relationship between dielectric constant and concentration or temperature. However, the quadratic equation is better than the linear one to describe the variation of the loss factor with temperature or concentration.
Esterification showed great advantages for the use of microwave irradiation in chemical reaction. It included reduction in reaction time, and provided distinct temperature profiles due to microwave environment during chemical reactions. The reason for rate enhancement of this type of reaction was also demonstrated from the temperature profile.
Microwave-assisted solvent free Maillard reaction model system, consisting of glucose and lysine, demonstrated that the heating method applied was not one of the crucial factors, but the temperature level was important during the chemical reaction.
The relationship of loss factor with yield of reaction showed that it is possible to use dielectric data to analyze, and monitor the chemical reaction. It provided a new methodology to analyze the reaction.
The relationship between the loss factor, loss tangent and the reaction time, and concentration of the material showed that it is also possible to use dielectric data at microwave frequencies of 2450 and 915 MHz to study chemical reactions, especially the kinetics.

Technologies such as direct broad cast satellite system (DBSS), Geosynchronous Earth Orbit (GEO) and Low Earth Orbit (LEO) satellite communications , global positioning system (GPS), high accuracy airborne navigation system and a large variety of radar systems demand for high level of antenna performance. Similar is the requirement for upcoming land based wireless systems such as cellular and indoor communication systems that is needed some more specific and additional features added to the antenna to compensate for the deficiencies encountered in system's performance. Though metallic antennas are capable enough to fulfil all the operational requirements, however at very high frequencies and under hostile temperature conditions they are constrained to face certain limitations. To avoid these constraints the performance of Dielectric Resonator Antennas (DRAs) is evaluated and their new applications are proposed. In the thesis, two types of antenna applications are sought :-First is for tracking and satellite applications that needs a larger aperture coverage in elevation plane. This coverage is realized with a good CP purity by proposing two ports dual linearly polarized DRA working at X-band. The DRA is excited by two orthogonal H-shaped aperture slots yielding two orthogonal polarizations in the broadside direction. A common impedance bandwidth of 5.9% and input port isolation of -35 dB are obtained. The broadside radiation patterns are found to be highly symmetric and stable with cross polarization levels -15dB or better over the entire matching frequency band. The maximum measured gain is found to be 2.5dBi at 8.4 GHz.- The 2nd type of antenna is a dual pattern diversity antenna to be used in the Body Area Network (BAN) context. This antenna combines a slot loop and DRA yielding broadside and end-fire radiation patterns respectively. Based upon the feeding techniques, the DG antenna is further divided into two categories one with planar feeds and the other with non-planar feeds (slot loop excited by planar CPW but DRA excited by vertical monopole) .Both types are successfully designed and measured upon body when configured into different propagation scenarios. The non-planar feeds antenna allows wider common impedance bandwidths than the planar feeds (4.95% vs 1.5%).In both cases, a maximum value of DG=9.5dB was achieved when diversity performance tests were carried out in rich fading environments. This value is close to the one (10 dB) theoretically reached in a pure Rayleigh environment and was obtained with efficiencies of 70% and 85% for the slot loop and the DRA respectively. Therefore, we conclude that these antennas could be used on the shoulders or the chest of professional clothes (firemen, policemen, soldier) where full planar integration is not a key issue but where the communication must be efficient in harsh environments and for various gestures, positions and scenarios

This research entailed the development of resonant dielectric sensors that utilising alternating electric fields at microwave frequencies. Characterisation and identification of biological samples is currently an expensive and time consuming procedure due to the extreme variation of seemingly similar biological systems. The work describes the development of resonant dielectric sensors for five distinct applications. The aim of the research was to develop non-invasive, affordable and compact dielectric spectroscopy sensors that may be used in-situ to characterise organic and biological systems. The suitability of using dielectric spectroscopy to a number of applications has been investigated. This is to address disadvantages of conventional laboratory analysis such as lengthy, costly and labour intensive assessment methods that require intermittent sampling and/or off site analysis. The research is structured into a series of progressive stages (work packages) that integrate and culminate into feasible inline analytical procedures that can quickly, safely and inexpensively assess a specified variable in organic and biological systems. Overall, a number of sensors using electromagnetic radiation at microwave frequencies were developed that have proven to be sensitive and extremely versatile to a number of detection and monitoring applications. Miniaturisation of microwave generation and analysis circuits will enable the sensors to be incorporated into feasible compact devices for in situ analysis of the analyte in question.

Dans cette thèse, on vise deux types d'applications de l’antenne à résonateur diélectrique (DRA): 1) La réalisation d’un élément rayonnant pour un réseau phasé embarqué sur un véhicule terrestre ou un avion. Cet élément de base requiert une couverture en élévation supérieure à celle des éléments imprimés pour permettre une poursuite typique comprise entre ±70°. La couverture dans un cône large est assurée avec une bonne pureté de polarisation circulaire en alimentant l’antenne à travers deux ouvertures à fente en H orthogonales parfaitement découplées en bande X. 2) La deuxième structure est destinée à la diversité d’antennes dans le contexte des réseaux corporels embarqués ou Body Area Network (BAN). L’antenne à diversité combine une antenne fente en boucle avec un DRA ce qui permet dans un espace compact de réaliser des diagrammes de type “broadside” et “endfire” respectivement. Les alimentations considérées sont de 2 types; Soit purement planaire (microruban et coplanaire) soit mixte en combinant une alimentation coaxiale et une alimentation coplanaire. Caractéristiques principales des antennes à résonateur diélectrique (DRA): Pour répondre aux attentes des utilisateurs en termes de débit, les systèmes de communication sans fils se tournent vers des fréquences de plus en plus élevées. La conséquence de cette montée en fréquence est notamment l’augmentation des pertes au niveau des éléments conducteurs et donc une diminution de l’efficacité globale des systèmes de communication. Dans ces circonstances, les DRA offre de meilleurs résultats par rapport à d'autres familles d'antennes à base d’éléments métalliques. De plus, les DRA offrent des pertes diélectriques négligeables, elles sont peu sensibles aux variations de température et s’intègrent facilement sur des technologies de fabrication planaires
Technologies such as direct broad cast satellite system (DBSS), Geosynchronous Earth Orbit (GEO) and Low Earth Orbit (LEO) satellite communications , global positioning system (GPS), high accuracy airborne navigation system and a large variety of radar systems demand for high level of antenna performance. Similar is the requirement for upcoming land based wireless systems such as cellular and indoor communication systems that is needed some more specific and additional features added to the antenna to compensate for the deficiencies encountered in system's performance. Though metallic antennas are capable enough to fulfil all the operational requirements, however at very high frequencies and under hostile temperature conditions they are constrained to face certain limitations. To avoid these constraints the performance of Dielectric Resonator Antennas (DRAs) is evaluated and their new applications are proposed. In the thesis, two types of antenna applications are sought :-First is for tracking and satellite applications that needs a larger aperture coverage in elevation plane. This coverage is realized with a good CP purity by proposing two ports dual linearly polarized DRA working at X-band. The DRA is excited by two orthogonal H-shaped aperture slots yielding two orthogonal polarizations in the broadside direction. A common impedance bandwidth of 5.9% and input port isolation of -35 dB are obtained. The broadside radiation patterns are found to be highly symmetric and stable with cross polarization levels -15dB or better over the entire matching frequency band. The maximum measured gain is found to be 2.5dBi at 8.4 GHz.- The 2nd type of antenna is a dual pattern diversity antenna to be used in the Body Area Network (BAN) context. This antenna combines a slot loop and DRA yielding broadside and end-fire radiation patterns respectively. Based upon the feeding techniques, the DG antenna is further divided into two categories one with planar feeds and the other with non-planar feeds (slot loop excited by planar CPW but DRA excited by vertical monopole) .Both types are successfully designed and measured upon body when configured into different propagation scenarios. The non-planar feeds antenna allows wider common impedance bandwidths than the planar feeds (4.95% vs 1.5%).In both cases, a maximum value of DG=9.5dB was achieved when diversity performance tests were carried out in rich fading environments. This value is close to the one (10 dB) theoretically reached in a pure Rayleigh environment and was obtained with efficiencies of 70% and 85% for the slot loop and the DRA respectively. Therefore, we conclude that these antennas could be used on the shoulders or the chest of professional clothes (firemen, policemen, soldier) where full planar integration is not a key issue but where the communication must be efficient in harsh environments and for various gestures, positions and scenarios

No
A small dielectric resonator antenna has been designed for ultra wideband (UWB) communication system applications. The antenna element is a rectangular low permittivity ceramic block, with a dielectric constant of 9.4, and the modified T-shaped feed network includes a 50 ohm microstrip line to achieve strong coupling, and some bandwidth enhancement. The antenna performance is simulated and measured over a frequency band extending from 3100 MHz to 5500 MHz; the impedance bandwidth over this interval is 55.8% with VSWR <; 2, making the antenna suitable for UWB applications.

At 0.18 microns and below minimum device dimensions in Ultra Large Scale Integrated Circuits, signal net parasitic delay amounts to 80% of the overall path delay. This leads to serious problems relating to signal timing, crosstalk, noise and power consumption. Although Copper is being used as an alternative to Aluminum interconnects to reduce the resistive component of the RC delays, finding a suitable material to replace Silicon Dioxide (SiO2) as the interlayer dielectric poses serious challenges. Most of the inorganic candidates are variants of SiO2, while the most prominent among polymeric materials belong to the polyparaxylylene family. The primary disadvantage of polyparaxylylene materials is their low thermal stability. While SiO2 based inorganic films exhibit excellent thermal stability, they offer only incremental improvement in the dielectric constant. The thin film deposition technique for these materials is important as it directly impacts the cost of manufacturing. Chemical Vapor Deposition is known to make high purity, conformal thin films, and is compatible with current silicon manufacturing technology. This research is primarily focused to develop materials which have (i) Low dielectric Constant; (ii) High thermal stability, and to deposit them using Chemical Vapor Deposition technique. The vision was to develop a composite thin film material with the thermal stability of SiO2 and the low dielectric constant of paraxylylenes. The first objective of this research was to develop a technique to deposit SiO2 films at near room temperatures. Thin conformal films of SiO2 were deposited at temperatures around 50°C using Di-acetoxy-di-tertiary-butoxy silane (DADBS) as the precursor. The thermal stability, optical and electrical properties of the codeposited thin films were systematically studied. It was possible to control the composition of these films smoothly and these films were shown to be of nanocomposite type. However, the thermal stability of these nanocomposite thin films was only marginally better than that of paraxylylenes. These films were then heat treated under oxygen to 'burn off' the polymer content. It was shown that annealing these films in oxygen environment leaves porous SiO 2 which exhibits the thermal stability of SiO2 and the porosity results in lower dielectric constant.

In the past few decades, the advancements in nanotechnology have significantly altered many fields of science and technology, especially electronics and integrated photonics. Free-space optics, on the other hand, has remained mostly unaffected, and even today "optics" reminds us of carefully shaped and polished pieces of various types of glasses and crystals lumped into lenses and beam shapers. Several of these devices are then combined into more complicated optical systems like microscopes and pulse shapers that are expensive, bulky, sensitive to various environmental factors, and require several alignment steps. This thesis contains my work on designing and utilizing structures engineered at the nano-scale, which are called metasurfaces, to implement compact optical elements and systems with capabilities beyond those of conventional refractive and diffractive optics. My contributions to this field are two-fold: I have developed and contributed to the development of new concepts that take metasurfaces beyond conventional difractive optics in various aspects, in addition to paradigm changing platforms for optical element and system design. Here, I first give an overview and a brief history about optical metasurfaces. Next I discuss the unprecedented capabilities of metasurfaces in controlling light based on its degrees of freedom like illumination angle and polarization. Then, I will focus on various novel metasurface platforms of conformal and tunable metasurfaces, 3D metasurface beam shapers, and integrated metasurfaces. I conclude with an outlook on future potentials and challenges that need to be overcome for realizing their wide-spread applications.

碩士
國立交通大學
電子研究所
84
For deep submicron CMOS technology the speed of the devices is limited more by interconnect delay and less by intrinsic gate delay. Change in the dielectric materials to reduced capacitance is probably one of the bestapproach to interconnection delay, also to power disspation and crosstalk. this thesis presents the film characteristics, thermal stability, leakage current and stress variations of three type of low-k SOG. Experimental results are compared with those of a conventional SOG.

碩士
國立交通大學
電子工程系
87
For ULSI circuits when feature size is scaled into the deep submicron region, The speed of the devices will be significantly limited by the interconnect delay. Low dielectric constant (K) materials will play a major role, with copper as the interconnect material, in offering to minimize the interconnect RC delay. A variety of inorganic or organic polymers, xerogel are being considered for low k applications. This thesis will describe two new siloxanes and porous xerogel with ultra-low dielectric constant for low k applications. We will explore thermal stability, moisture uptake, stress variations, leakage current and electrical dielectric breakdown strength of three types of low-k materials. In this work, the application of low-k to copper metallization is also investigated. Without MoN barrier, the Cu/T23(cured at 350C)/Si MOS capacitors are very leak after 3500C anneal and the thermal stability of Cu/T24(cured at 500C)/Si MOS capacitors is found to reach 400C. For the Cu/MoN/ T24(cured at 500C)/Si MOS capacitors, the stability temperature is up to 500C.

Today's communications systems require use of broadband antennas to meet high capacity requirements. Furthermore, some applications require smaller antenna sizes. In this work, a broadband Dielectric Resonator Antenna (DRA) for WLAN applications is presented. The antennas presented are compact in size, have the broadside radiation patterns and high radiation efficiency. The bandwidth of the DRA depends on the dielectric material, its shape, as well as the excitation technique used to feed the antenna. The three antennas presented in this thesis are of half cylindrical shape, mounted on ground planes and excited by aperture coupling slot. A parasitic U slot is part of the feeding network for more coupling and bandwidth enhancement. The antennas have good radiation characteristics and operate over a wide band of frequencies. Ansoft HFSS is used for the antenna simulation. CST Microwave studio is also used to compare the accuracy of time domain and frequency domain analysis of the DRAs. The DR material is Rogers RO3010 (TM) with [varepsilon] r = 10.2, and a dielectric loss tangent of 0.0035. The substrate material is Rogers RT/Duroid 5880 (TM) with [varepsilon] s =2.2, a loss tangent of 0.0009, and 0.767 mm thickness. The half-cylindrical DRA is used to have the TEo13 mode excited. The radiation patterns of the three antennas are similar to that of a magnetic monopole which has the broadside radiation pattern. Parasitic U-shaped slots are used with the three presented antennas to enhance the bandwidth by exciting a dual resonant frequency in the TE 01e mode. These slots have similar radiation characteristics to those of the half cylindrical DRAs so the overall radiation patterns of these antennas are not deteriorated. For the fabricated antennas, they have broadside radiation characteristics in H and E planes. As for the impedance bandwidth, the half cylindrical ORA has 24 % fractional bandwidth. For the half cylindrical ORA backed with a rectangular dielectric resonator, 32% bandwidth is achieved. A bandwidth of29% is achieved in the case of half volume Elliptical ORA. The gain of the three antennas slightly changes around 5 dBi which is good for the WLAN applications.

碩士
國立成功大學
電機工程學系
89
It is found that low-level doping of ZnO (1wt%) and V2O5 (up to 2 wt%) can significantly improve the densification ability and the dielectric properties of (Zr0.8,Sn0.2)TiO4 ceramics. (Zr0.8,Sn0.2)TiO4 ceramics with additives could be sintered to a theoretical density higher than 95% at 1300℃ due to the liquid-phase effect of V2O5 addition. The dielectric constant (εr) increased with increasing sintering temperature and saturated at 1300℃. The temperature coefficient of resonant frequency (τf) was not significantly affected while the unloaded quality factor Q was promoted by V2O5 addition. Theεr value of 37.3, the Q×f value of 51500 (at 7 GHz) and theτf value of -2.1ppm/℃ were obtained for the 1wt% ZnO-doped (Zr0.8,Sn0.2)TiO4 ceramics with 1wt% V2O5 addition sintered at 1300℃. (1-x)CaTiO3-xCa(Mg1/3Nb2/3)O3 solid solution exhibited orthorhombic crystal structures for all compositions. With x=0.66, a new microwave dielectric ceramic material 0.34CaTiO3-0.66Ca(Mg1/3Nb2/3)O3 is suggested and possesses the dielectric properties of a dielectric constant εr of 48, Q×f value of 32500 (at 6.7GHz) and a τf value of -2ppm/℃ at 1450℃ for 3h. Further improvement of the Q×f value can be achieved by extending the sintering time to 6h. It reveals a higher Q×f value of 34000 (at 6.7GHz) without degrading other microwave dielectric properties of 0.34CaTiO3-0.66Ca(Mg1/3Nb2/3)O3 ceramics. In the recent, miniature and low cost bandpass filters are very important in mobile communication systems. The planar filter structure is one of the possible choices for its compactness when realized with a high dielectric constant substract. In the paper, we used microstrip hairpin resonators to fabricate microwave bandpass filter based on direct-coupled mechamism. In the aspect of the filter substract manufacture, we used ZST and Al2O3 to be the substracts of the filter. ZST have been used due to its good temperature stability, high Q value and high relative dielectric constant, respectively so that the filter can be miniaturized and realized good frequency response.

All-dielectric metasurfaces have received significant attention in the past years, and have been established as a platform for efficient manipulation of optical beams. Advances in the design and fabrication of such dielectric metasurfaces have led to the development of several ultra-thin optical metadevices, including flat lenses, beam converters, deflectors and holograms. Composed of periodic or aperiodic lattices of dielectric nanoparticles, metasurfaces exhibit low absorption in the infrared and visible spectral ranges. Low losses allow nanoparticles to exhibit Mie-type resonances with a higher quality-factor in comparison to their plasmonic counterparts. Furthermore, Mie-type resonances in dielectric nanoparticles offer two independent families of resonant modes - electric and magnetic. The far-field interference of these two types of resonant modes leads to fundamentally new effects, such as unidirectional scattering, unconventional reflection behaviour associated with the generalised Brewster effect and near-unity transmission in the so-called Huygens' regime. Operating in the Huygens' regime of the dielectric metasurfaces enables the combination of near-unity transmission together with a full range of phase modulation, thus being the key to enabling functional dielectric metasurfaces with nearly 100% efficiency. Most functional dielectric metasurfaces to date are based on static designs, defined through geometrical parameters, such as nanoparticle shape, size, and array layout. However, in many applications, it is crucial to enable dynamic tunability of the device functionality with time. For example, the focal distance of a camera lens needs to be changed when taking pictures of objects at different distances; the position of the ranging beam in a LIDAR (light imaging, detection, and ranging) for driverless vehicles needs to scan different directions. Therefore, implementing dynamic control} over the response of the metasurfaces is of paramount importance for their practical implementation. In this thesis, I discuss possible ways to achieve tunability from dielectric metasurfaces. At first, I consider existing methods, their pros and cons, as well as possible applications. Further, I offer several methods that I developed and investigated, both theoretically and experimentally. Namely, I describe tuning by changing the properties of resonator material, where I utilise a thermo-optic effect to control the refractive index of resonator particles and consequently the optical response of metasurfaces. Next, I consider tuning by changing the properties of surrounding material, first theoretically, and later demonstrating experimental realisation of this concept using a liquid crystal as a tuning medium. Finally, I describe two tunable metadevices: one, for switching a beam deflection, and second, for active tuning of spontaneous emission.

yes
A compact dielectric resonator antenna (DRA) for wideband applications is proposed. Two cylindrical dielectric resonators which are asymmetrically located with respect to the center of a rectangular coupling aperture are fed through this aperture. By optimizing the design parameters, an impedance bandwidth of about 29%, covering the frequency range from 9.62 GHz to 12.9 GHz, and a gain of 8 dBi are obtained. Design details of the proposed antenna and the results of both simulation and experiment are presented and discussed.

碩士
國立交通大學
電子工程學系
85
As the CMOS geometry shrinks to 0.35um and beyond, low dielectric constant properties become increasingly important in the selection of intermetal dielectric oxide. In this thesis, we introduce a low-k SOG material that is Hydrogen Silsesquioxane (HSQ) -based flowable oxide (FOx) and study its characteristics when used for low-k IMD applications. In the present study, film shrinkage has been reported. The FOx film thickness shrinkage is smaller than 5% that exhibits less reduction than the conventional SOGs (reduce to 10 %). Thermal properties of the FOx film have also been investigated. The FOx film has good crack resistance and will not crack till 700oC. The plasma treated films show smaller variations in film stress than as spun FOx film during the thermal heating and cooling cycle. Plasma curing effects and water absorption resistance of FOx have been realized. H2 plasma curing treatment causes the lowest dielectric constant of FOx. On the other hand, O2 plasma curing treatment makes the FOx film higher moisture absorption due to the formation of Si-OH bonds and NH3 plasma curing treatment makes lower moisture absorption. The formation of Si-OH bonds is caused by the O component in the air incorporating into the film structure. In addition, curing time and temperature effects are also stated. It is found that we should carefully select the optimal curing time and temperature to get Si-H rich film for conserving low dielectric constant properties of the FOx film. If the Si-H bonds retain ata high level and the cage-like/network ratio is not too small, the low dielectric constantproperty of the film will conserve. Mechanisms of the reduction in oxide's dielectric constant have been reported to explain the relationship between ionic polarization density and electronic polarization density with dielectric constant. Finally, basic electrical characteristics such as C-V and I-V measurements are measured for each plasma curing FOx film.

博士
國立交通大學
影像與生醫光電博士學位學程
105
Physics of dielectric heating in complex mesogenic materials especially liquid crystal materials (LCs) has been a complicated topic. The dielectric relaxation process for mesogenic materials is usually chaotic without obvious order. In the last century, the Debye relaxation law, the Cole–Cole equation, the Cole–Davidson equation, the Havriliak–Negami relaxation, and the Kohlrausch–Williams–Watts function have successively been derived from statistical mechanics. In this thesis, we propose a general dielectric relaxation law that unifies the above-mentioned formulas, and we point out that these formulas are only variations of the general formula in different conditions. We applied the general dielectric relaxation formula for derivation of the law of general dielectric heating. This formula is especially suited for describing the easily induced dielectric heating effect in dual-frequency liquid crystals (DFLCs). In this thesis, we further exploit this heating effect in various applications for both nematic DFLCs and cholesteric DFLCs (DFCLCs). For nematic DFLCs, we propose to apply dielectric heating for reducing driving voltage. The dielectric heating results in increased cross-over frequency and also reduces viscosity of DFLCs to allow for lower driving voltage. For DFCLCs, we demonstrated that with dielectric heating, local deformation in cholesteric structure can be achieved. The defect mode in cholesteric structure can be controlled through the degree of dielectric heating. Furthermore, we have shown that cholesteric film with binary chiral agents exhibits electrically tunable selective reflection in visible wavelength. Lastly, we demonstrated the electrothermo-optical effect based on dielectric heating. Comparing to the commonly-known electro-optical effects, the electrothermo-optical effect exhibits anomalous behaviors. Based on dielectric heating, this thesis proposed various practical applications in the field of optics.

碩士
國立成功大學
電機工程學系碩博士班
101
There are two main subjects in this thesis. First, we have synthesized two novel microwave dielectric materials which have not been developed and applied in academic and industrial fields yet. We also discuss the dielectric and microwave differences caused by morphology, physical properties and process conditions. Second, there will be a discussion of passive components and improvement of circuit size in different substrates. First part is the introduction of two novel microwave dielectric materials, MgSnNb2O8 and Mg2YVO6. MgSnNb2O8 has Wolframite structure belonged to monoclinic lattice system and the space group is P2/c(13). MgSnNb2O8 has the best microwave dielectric propertiesεr ~ 22.05、Q×f ~ 17,100 GHz (at 6.857GHz)、τf ~ –54.6 ppm/℃ while sintering at 1430℃ for 6 hours. Mg2YVO6 has Zircon structure belonged to tetragonal lattice system and space group is I41/amd (141). Mg2YVO6 has the best microwave dielectric properties εr ~ 10.88、Q×f ~ 68,300 GHz (at 10.249 GHz)、τf ~ –53.9 ppm/℃ while sintering at 1290℃ for 4 hours. Second part is the designation and fabrication of a microstrip band-pass filter and the first band is controlled at 2.45 GHz. This filter is constructed by two T-shaped resonators and a U-shaped hair-pinned resonator centered at middle. The U-shaped microstrip is parallel coupled by two T-shaped microstrips. The open stub side on T-shaped is designed to suppress the spurious response at second band. At last, the pattern was printed on FR4, Al2O3 and Mg2YVO6–1290℃–4hrs substrates. By comparing the frequency of measured results, we can observe the improvement of performance and size reduction by applying high dielectric constant and loss dielectric loss substrates.

博士
國立成功大學
電機工程學系碩博士班
98
Microwave dielectric resonators (DRs) which are fabricated by high dielectric constant, high quality factor, and good temperature stability of microwave dielectric materials are suitably applied in antennas, filters, oscillators, and diplexers. Recently, with the rapidly progress in the microwave communication systems, miniaturization and performance enhancement have become two main requirements of the microwave devices. Therefore, high quality factor dielectric materials can be utilized in designing high-performance microwave devices in communication system. Moreover, the integration of dielectric materials is also main method to carry out the miniaturization of microwave devices. In addition, to develop microwave dielectric materials, lower sintering temperatures plays an important role in the future. As mentioned above, the main study of this dissertation is divided five parts which preparation of high dielectric constant, high quality factor, low sintering temperature microwave dielectric materials, fabrication of high quality Mg4Ta2O9 dielectric thin films and their applications on microstrip bandpass filters. 1.Development of High Q Microwave Dielectric Materials [a]Study of Mg2TiO4 Ceramics: (1)Binary titanate ceramic Mg2TiO4 ( ~ 14, Q×f ~ 150,000 GHz, and τf ~ –50 ppm/°C), having extremely high quality factor, were reported as promising dielectric ceramics for microwave applications. Their low cost even brought much more attention. In fact, they have already been used as dielectric materials for GPS antennas and wireless LAN filters. Therefore, the spinel-structured Mg2TiO4 is worthy to investigate its microwave properties. In this dissertation, with partial replacement of Mg by Co or Ti by Sn, the Q×f of the dielectrics (Mg0.95Co0.05)2TiO4 ( ~ 15.7, Q×f ~ 286,000 GHz, and τf ~ –52.5 ppm/°C) and Mg2(Ti0.95Sn0.05)O4 ( ~ 15.57, Q×f ~ 318,000 GHz, and τf ~ –45.1 ppm/°C) can be easily boosted to a value higher than 250,000 GHz and retain compatible and τf. (2)In order to achieve temperature-stable materials, CaTiO3, Ca0.61Nd0.26TiO3, Ca0.6La0.8/3TiO3, Ca0.8Sm0.4/3TiO3, and Ca0.8Sr0.2TiO3 were added to (Mg0.95Co0.05)2TiO4 and Mg2(Ti0.95Sn0.05)O4 ceramics, respectively. Addition of compensators, having much smaller grain sizes in comparison with that of (Mg0.95Co0.05)2TiO4 and Mg2(Ti0.95Sn0.05)O4, could effectively hold back abnormal grain growth in the (Mg0.95Co0.05)2TiO4 and Mg2(Ti0.95Sn0.05)O4 matrixes. Hence, using the compensators can effectively lower the sintering temperature of the ceramic bulks. Dielectric characteristics and sintering behavior of these ceramic systems were investigated. A two-phase system, which was confirmed by the XRD patterns and the EDX analysis. Moreover, the microstructures of the sintered bulks were characterized by SEM. (3)As mentioned above, the optimal microwave dielectric properties are achieved in 0.92(Mg0.95Co0.05)2TiO4–0.08Ca0.8Sr0.2TiO3 ceramics sintered at 1300°C for 4 h with a dielectric constant ( ) value of 19.22, a quality factor (Q×f) value of 123,200 GHz, and a temperature coefficient of resonant frequency (τf) value of 2.8 ppm/°C. Furthermore, in order to lower the sintering temperature, sintering aid such as B2O3 was used to produce the liquid phase that degrades the sintering temperatures. The microstructures and the microwave dielectric properties with B2O3 additions were investigated. [b] Study of ZnX2O6 (X = Nb and Ta) Ceramics: (1)Partial Replacement of ZnNb2O6 Ceramics The effects of substituting Nb5+ with Ta5+ on the microwave dielectric properties of the ZnNb2O6 ceramics were investigated in this dissertation. The forming of Zn(Nb1-xTax)2O6 (x = 0–0.09) solid solution was confirmed by the measured lattice parameters and the EDX analysis. A fine combination of microwave dielectric properties ( ~ 24.57, Q×f ~ 152,000 GHz, and τf ~ –71.1 ppm/°C) was achieved for Zn(Nb0.95Ta0.05)2O6 solid solution sintered at 1175°C for 2 h. (2)Partial Replacement of ZnTa2O6 Ceramics ZnTa2O6 microwave dielectric materials have been developed as the microwave dielectric resonators in the past, because the dielectric resonators fabricated by ZnTa2O6 ceramics reveal the excellent microwave dielectric properties. However, the quality factor of ZnTa2O6 ceramic is still not good enough for the applications at the microwave frequency. In order to improve the microwave dielectric properties, with the partial replacement of ZnTa2O6 ceramics were investigated. The forming of (Zn0.95M2+0.05)Ta2O6 (M2+ = Co, Mn, Mg, and Ni) and Zn(Ta0.95Nb0.05)2O6 solid solutions were confirmed by the XRD patterns, HR-TEM lattice images, and the EDS analysis. 2.Research of High K Microwave Dielectric Materials Several complex perovskites ceramics A(B2+0.5B4+0.5)O3 (where A = La, Nd, and Sm; B2+ = Mg, Zn, and Co; B4+ = Ti and Sn) have been reported due to their excellent microwave dielectric properties. Among them, La(Mg0.5Ti0.5)O3 has a high dielectric constant ( ~ 29), a high quality factor (Q×f value ~ 75,500 GHz), and a large negative temperature coefficient of resonant frequency (τf ~ –65 ppm/°C). In order to compensate the negative τf of the La(Mg0.5Ti0.5)O3 ceramics, Ca0.8Sm0.4/3TiO3 and Ca0.8Sr0.2TiO3 perovskite which have positive τf had been added. The experiment result showed that 0.5La(Mg0.5Ti0.5)O3–0.5Ca0.8Sr0.2TiO3 have the best microwave dielectric properties, it’s ~ 47.12, Q×f ~ 35,000 GHz, and τf ~ –4.7 ppm/°C. In addition, the X-ray diffraction (XRD) patterning and scanning electron microscopy (SEM) analysis were also employed to study the crystal structures and microstructures of the ceramics. 3.Investigation of Low-Temperature Sintering Microwave Dielectrics Using CuO-Doped Zn(Nb0.95Ta0.05)2O6 Ceramics The influence of CuO additions on the sintering behavior and microwave dielectric properties of Zn(Nb0.95Ta0.05)2O6 ceramic and its chemical compatibility with Ag have been investigated. The CuO additions not only effectively lower the sintering temperature of Zn(Nb0.95Ta0.05)2O6 ceramics to 930°C, the optimized sintering temperatures also decrease with increasing CuO contents due to the liquid phase effect. The Q×f value is a function of the sintering temperature and the amount of CuO addition. With 4.5 wt% CuO addition, it varies from 8,500 to 77,200 GHz as the sintering temperature increases from 840°C to 930°C for 2 h. For low-firing multilayer applications, a combination of dielectric properties with an ~ 22.87, a Q×f ~ 77,200 GHz, and a τf ~ –70.8 ppm/°C can be achieved for 4.5 wt% CuO-doped Zn(Nb0.95Ta0.05)2O6 ceramic sintered at 930°C for 2 h. 4.Fabrication and Characteristics of Mg4Ta2O9 Dielectric Thin Films by RF Magnetron Sputtering Recently, high permittivity dielectric films with low leakage current and high break-down voltage are of the great importance for a variety of integrated devices, such as storage capacitors in dynamic random access memory (DRAM). In this dissertation, the Mg4Ta2O9 target was prepared and used for deposition. The crystal structure and surface morphology of the films affected by deposition conditions, such as RF power and sputtering time. The physical and electrical characteristics of the thin films were investigated. 5.Design and Fabrication of Microstrip Bandpass Filters The microstrip bandpass filters of SIR with a (skew-symmetric) feed structure and open-stubs are presented. In this dissertation, using high permittivity ceramic substrates to miniaturize the sizes of Butterworth bandpass filters are investigated. The selectivity and stopband rejction of the designed filters can be improved significantly by utilizing the feed structure and open-stubs. The responses of the bandpass filters using Al2O3 ( = 9.8, = 0.0005, 1.6-mm thickness), and 0.92(Mg0.95Co0.05)2TiO4–0.08Ca0.8Sr0.2TiO3 with 0.5 wt% B2O3 addition ( = 18.07, = 0.0001, 1.6-mm thickness) ceramic substrates are designed at a center frequency of 2.4 GHz. The compact size and high-performance of the filter are presented in this thesis.

碩士
國立成功大學
電機工程學系碩博士班
93
Abstract 　　The microwave properties of 0.95MgTiO3 – 0.05CaTiO3 dielectric ceramic materials are discussed in this paper. By adding different sintering aids ZnO、B2O3 and SiO2 respectively, we study the existence effects of liquid phase for the microwave properties of 0.95MgTiO3 – 0.05CaTiO3. 　　There are three part about the dielectric material. First, we discuss the properties of 95MCT with single sitering aids. Second, we discuss 0.95MgTiO3 – 0.05CaTiO3 adding a trace of ZnO. Third, we mix 0.95MgTiO3 – 0.05CaTiO3 with those three different sintering aids.. The experiment results show that 0.95MgTiO3 – 0.05CaTiO3 with 1wt% ZnO addition can efficiently reduce sintering temperature to 1350 oC, and it appears the best property: εr~20.3, Q×f~66300. Hence, the microwave properties of 0.95MgTiO3 – 0.05CaTiO3 dielectric ceramic materials is improved. 　　In addition, we design and fabricate compact SIR band-pass filters with 2.4GHz central frequency and 10% bandwidth on FR4, Al2O3 and 0.95MgTiO3 – 0.05CaTiO3 substrates.

碩士
國立臺南大學
電機工程研究所
99
Recently, the dielectric resonator antenna has been extensively studied owing to its numerous advantages such as high gain, light and compact size 31×21×5.1 mm3. The shapes of DRAs are various and different, such as hemispherical, cylindrical and rectangular. DRAs can be excited by different feeding method, such as coaxial feed, microstrip line and co-planar lines. The DRAs can be completed low profile due to high dielectric permittivity of the materials. A new wideband rectangular dielectric resonator antenna is proposed. The rectangular dielectric resonator is feed by mircostrip. The antenna provides an impedance bandwidth of 131% for S11 ≦ -8 dB and directional radiation pattern. The antenna characteristics including return loss and radiation patterns were analyzed and discussed. In this thesis, a monopole antenna conformed standard (1.96 ~ 6.17 GHz) is proposed. There is a lower frequency in the mircostrip antenna is created by the high dielectric resonator. There is a fundamental mode in the rectangular resonator which is half-wavelength. The broad bandwidth is because of two close resonator frequencies.

[ES] Conocer las propiedades electromagnéticas de los tejidos biológicos con la mayor exactitud posible tiene una gran importancia en el diseño de un elevado número de aplicaciones biomédicas. El diseño de dispositivos médicos inalámbricos, antenas superficiales e intracorporales, evaluación de tasas de absorción electromagnética, técnicas de tratamiento y detección de cáncer como la hipertermia e imágenes médicas son ejemplos de aplicaciones que requieren esta información para su desarrollo. Debido a que el cáncer provoca modificaciones estructurales en las células que a su vez generan cambios en las propiedades electromagnéticas, es posible desarrollar aplicaciones de detección de cáncer que se basen en este hecho. Un objetivo potencial es el cáncer de colon (CRC), debido a que los tejidos de colon sospechosos son accesibles de forma más o menos sencilla durante procedimientos endoscópicos. Este tipo de cáncer es uno de los más extendidos, siendo responsable de aproximadamente el 10% de casos y muertes totales. Existe un gran número de factores de riesgo que pueden explicar la aparición de la enfermedad, aunque esencialmente la probabilidad se incrementa significativamente con el aumento de la edad de la población. Los programas de cribado sobre la población son críticos: si el cáncer se detecta en etapas tempranas, la probabilidad de sobrevivir se incrementa en gran medida, y además se reducen los costes asociados. Uno de los objetivos principales de esta tesis es proponer aplicaciones que ayuden en la detección de CRC durante la colonoscopia haciendo uso de las diferencias en las propiedades electromagnéticas. Aparte de mejoras en el diagnóstico, complementar la colonoscopia puede conllevar otros beneficios colaterales como una reducción en la carga de anatomía patológica. Para demostrar la viabilidad y el potencial desarrollo futuro de estas aplicaciones, en esta tesis se miden y se trata de encontrar diferencias entre las propiedades electromagnéticas de tejidos sanos, cancerosos y patológicos de colon humano. Las medidas han sido llevadas a cabo mediante la técnica del coaxial terminado en abierto. Con el propósito de incrementar la precisión del método, se ha evaluado el principio de funcionamiento y se ha mejorado el proceso de calibración. Dos fuentes de tejido de colon han sido analizadas en esta tesis: tejidos procedentes de colonoscopias (biopsias) y tejidos obtenidos a partir de procedimientos quirúrgicos. Aparte de tejido sano, se estudian las siguientes patologías: Adenocarcinomas (CRC), adenomas sin displasia, adenomas con bajo grado de displasia, adenomas con alto grado de displasia, hiperplasias y hamartomas. Debido a la alta variabilidad entre distintos sujetos, las propiedades electromagnéticas de los tejidos sospechosos de un paciente en concreto deben ser siempre comparadas con las propiedades de sus tejidos sanos, no evaluadas de forma independiente. El segundo gran objetivo de esta tesis es el desarrollo de una nueva base de datos de las propiedades electromagnéticas de tejidos biológicos medidas in vivo. Ahora mismo, las colecciones disponibles están limitadas en número de tejidos o frecuencias caracterizadas, obligando a los investigadores a escoger bases de datos más completas pero realizadas ex vivo. No obstante, usar este tipo de colecciones tienen fuentes de incertidumbre adicionales dado que las medidas están condicionadas por la deshidratación de los tejidos y la perdida de flujo sanguíneo. El desarrollo de esta nueva base de datos puede facilitar el diseño de aplicaciones que requieran conocer las propiedades electromagnéticas con alto grado de precisión.
[CAT] Conéixer les propietats electromagnètiques dels teixits biològics amb la major exactitud possible té una gran importància en el disseny d'un gran nombre d'aplicacions biomèdiques. El disseny de dispositius metges sense fil, antenes superficials i intracorporales, l'avaluació de taxes d'absorció electromagnètica, tècniques de tractament i detecció de càncer com ara la hipertèrmia i imatges mediques són exemples d'aplicacions que requerixen esta informació. Com el càncer provoca modificacions estructurals en les cèl·lules que generen canvis en les propietats electromagnètiques, es possible desenrotllar aplicacions de detecció de càncer que es basen en este fet. Un objectiu potencial és el càncer de colon (CRC), pel fet que els teixits de colon sospitosos són accessibles de forma més o menys senzilla durant procediments endoscòpics. Este tipus de càncer és un dels més estesos, sent responsable d'aproximadament el 10% de casos i morts totals. N'hi ha un gran nombre de factors de risc que poden explicar l'aparició de la malaltia, encara que en resum la probabilitat s'incrementa significativament amb l'augment de l'edat de la població. Els programes de cribratge sobre la població són crítics. Si el càncer es detecta en etapes primerenques, la probabilitat de sobreviure s'incrementa en gran manera, i a més es reduïxen els costos associats. Un dels objectius principals d'esta tesi és proposar aplicacions que ajuden en la detecció de CRC durant la colonoscòpia fent ús de les diferències en les propietats electromagnètiques. A banda de millores en el diagnòstic, complementar la colonoscòpia pot comportar altres beneficis col·laterals com una reducció en la càrrega d'anatomia patològica. Per a demostrar la fiabilitat i el potencial desenrotllament d'aquestes aplicacions, en aquesta tesi es mesuren i es tracta de trobar diferències entre les propietats electromagnètiques de teixits sans, cancerosos i patològics de colon humà. Les mesures han sigut realitzades mitjançant la tècnica del coaxial acabat en obert. Amb el propòsit d'incrementar la precisió del mètode, s'ha avaluat el seu principi de funcionament i s'ha millorat el procés de calibratge. Dos fonts de teixit de colon s'han analitzat en aquesta tesi: teixits procedents de colonoscòpies (biòpsies) i teixits obtinguts a partir de procediments quirúrgics. Apart de teixit sà, s'estudien els següents teixits: Adenocarcinomes (CRC), adenomes sense displàsia, adenomes amb baix grau de displàsia, adenomes amb alt grau de displàsia, hiperplàsies y hamartomes. Degut a l'alta variabilitat entre diferents subjectes, les propietats electromagnètiques dels teixits sospitosos d'un pacient en particular han de ser comparades amb les propietats dels seus teixits sans, no avaluats independentment. El segon gran objectiu d'esta tesi és el desenrotllament d'una nova base de dades de les propietats electromagnètiques de teixits biològics mesurades in vivo. Ara mateix, les col·leccions disponibles estan limitades en nombre de teixits o freqüències caracteritzades, obligant els investigadors a triar bases de dades més completes però realitzades ex vivo. No obstant això, este tipus de col·leccions te fonts d'incertesa addicionals atés que les mesures estan condicionades per la deshidratació dels teixits i la pèrdua de flux sanguini. El desenrotllament d'esta nova base de dades pot facilitar el disseny d'aplicacions que requerisquen conéixer les propietats electromagnètiques amb alt grau de precisió.
[EN] Nowadays, a careful knowledge of the electromagnetic properties of biological tissues is required for developing a great number of applications. The development of wireless medical devices, the design of in-body and on-body antennas, specific absorption rate evaluations, cancer treatment techniques such as hyperthermia and detection techniques like medical imaging are some examples of applications that rely on these data. Since cancer causes modifications on the biological structure of cells that can lead in turn to changes in the electromagnetic properties of the tissues, it is possible to develop novel detection applications taking advantage of it. One potential target is colorectal cancer (CRC), as suspicious tissues can be accessed quite easily through colonoscopy procedures. This kind of cancer is one of the most spread kinds, being responsible of about 1 out of 10 new cancer cases and deaths. There are several risk factors currently related to the apprising of this cancer, although in essence the higher the age of the population, the higher the incidence of CRC. Screening programs are key for detecting and diagnosing cancer: if found at early stages, the probability of survival increases greatly, and the cost of the treatment can be reduced as well. One of the major objectives of this dissertation is proposing applications for detecting CRC that aid in the colonoscopy procedures by making use of the differences in electromagnetic properties. Aside from enhancement in the diagnosis of CRC, improving the colonoscopy procedure can lead to collateral benefits like a lowering of the burden of anatomical pathology unit. With the aim at demonstrating the feasibility and the potential future development of these applications, in the framework of this thesis the dielectric properties of healthy, cancerous and pathological human colon tissues are measured and compared in order to find electromagnetic differences. Measurements are carried out by means of an open-ended coaxial system. Its principle of operation has been revisited with the aim at maximizing the accuracy of the method, and the calibration procedure has been optimized serving the same purpose. Two main sources of colon tissue have been analyzed: samples from colonoscopy biopsies and samples from surgery resections. Besides healthy tissue, the following colon tissues have been characterized: Adenocarcinomas (CRC), adenomas without dysplasia, adenomas with low-grade dysplasia, adenomas with high-grade dysplasia, hyperplastic polyps and hamartomatous polyps. Given the variability that can appear among subjects, the electromagnetic properties of suspicious tissues from a particular patient have to be always compared with those of his healthy ones, not evaluated independently. The second major objective of this thesis involves the development of a new database of electromagnetic properties of biological tissues obtained at in vivo conditions. Nowadays, the available collections are limited either in the number of tissues or the measured frequencies, and hence researchers have to make use of more complete databases but that were performed ex vivo. The drawback of using these collections is that results can be compromised by factors such as lack of blood perfusion and tissue dehydration. Developing this new database can facilitate the design of applications that needs of a careful knowledge of these properties.
Fornés Leal, A. (2019). Dielectric Characterization of Biological Tissues for Medical Applications [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/132188
TESIS

碩士
國立交通大學
電子工程學系
85
In this thesis, we explore five different kinds of spin-on low dielectric constant materials. We characterize their physical and electrical properties. In physical properties, we focus on film moisture absorbance and thermal stability. We use thin film stress measurement system and FTIR to understand their properties. We find that fluorinated polymers have better characteristics.In electrical properties, we explore the leakage current, breakdown field, and dielectric constant. Fluorinated polymers have lower leakage current, higher breakdown, and lower dielectric constant but the film adhesion on silicon or oxide is poor. We also explore the effect of copper on low dielectric film. Without barrier metal, FOX-15 is very leak after 350 oC anneal. Without barrier metal, PAE-2 cured at 500 oC can withstand Cu diffusion up to 400 oC anneal. With diffusion barriers, the thermal stability can reach 500 oC.

碩士
國立聯合大學
電機工程學系碩士班
100
This paper is divided into two main parts. In the first part, the effects of B2O3 addition on the sintering behavior and the microwave dielectric properties of CaLa4Ti4O15 ceramics have been discussed. The experiment results show that the CaLa4Ti4O15 ceramics with B2O3 additions can effectively reduce the sintering temperature. At 1220°C, CaLa4Ti4O15 ceramics with 0.5 wt.% of B2O3 additions possesses a dielectric constant of 46, a Q×f value of 23,000GHz, and a temperature coefficient of resonant frequency of -19.72ppm/°C. 　　Besides, the effects of the microwave dielectric properties of Zr4+ substituted for Ti4+ to from CaLa4(Ti(1-x)Zrx)4O15(x=0.01~0.1) ceramics have been discussed. The experiment results show that the dielectric properties can be inprove with Zr4+ substitution for Ti4+. When x=0.05, the specimen exhibited excellent properties of εr=45.75, Q×f=48,000GHz, τf=-12.32ppm/°C with sintered at 1550°C for 4h.　　 　　Finally, the microwave dielectric properties of (1-x)Nd(Co1/2Ti1/2)O3-x(Ca0.8Sr0.2)TiO3 ceramics have been discussed. For this results, a dielectric constant of 44.5, a value of 18,000GHz, and a temperature coefficient of resonant frequency of -2.4ppm/°C for 0.5Nd(Co1/2Ti1/2)O3-0.5(Ca0.8Sr0.2)TiO3 ceramics at 1340°C for 4h is proposed in this experiment. 　　In the second part, the helix antenna has been designed and fabricated by using 0.5Nd(Co1/2Ti1/2)O3-0.5(Ca0.8Sr0.2)TiO3 ceramic have been discussed.

碩士
東海大學
電機工程學系
106
The microwave dielectric properties of the Ca0.99Zn0.01La5(Ti1-xSnx)5O17, Ca0.97Zn0.03La5(Ti1-xSnx)5O17 and Ca5Nb4Ti1-xLaxO17 are discussed in this paper. By doping with SnO and La2O3 to study the effect of its microwave characteristics. The experimental results show that Ca0.99Zn0.01La5(Ti1-xSnx)5O17 has the best dielectric properties at x=0.02 and sintering temperature of 1500°C (εr~45.5, Q×f~15,000 GHz, τf~- 7.1 ppm/°C). Ca0.97Zn0.03La5(Ti1-xSnx)5O17 has the best dielectric properties at x=0.06 and sintering temperature of 1475°C (εr~37.5, Q×f~16,000 GHz, τf~−9.6 ppm/°C. ). Ca5Nb4Ti1-xLaxO17 has the best dielectric properties (εr~42.5, Q×f~23,000 GHz, τf~58 ppm/°C) at x=0.9 sintering temperature of 1450 °C. In addition, this paper uses FR4, Al2O3 and Ca0.97Zn0.03La5(Ti0.04Sn0.06)5O17 three different substrates, using hairpin low-pass filter to simulate with IE3D, we can find that C97ZLTS frequency response performance is not as good as FR4 and Al2O3, but it can reduce filter size.