No description available.

No description available.

<p>The continuous reduction of feature size in silicon-based electronic integrated circuits (ICs) is accompanied by devastating propagation delay time and power consumption that have become known as the “Interconnect Bottleneck”. Optical interconnection is a proposed solution that is poised to revolutionize the data transmission both within and between ICs. By forming the optical transmission and functional elements from silicon, they can be monolithically incorporated with standard ICs using the established CMOS (Complementary Metal Oxide Semiconductor) infrastructure with minimal incremental cost. A key required functional element is the photodetector, which provides optical-toelectrical conversion of signals. In this thesis, a method of achieving such conversion is explored, which uses the optical absorption at 1550 nm wavelengths provided by lattice defects. The physics governing defect-enhanced silicon waveguide photodiode operation is described, and a device model is used to verify the posited detection process and propose design improvements. The model was used to design a novel photodetector structure using a waveguide formed by the LOCOS (LOCal Oxidation of Silicon) process with a poly-silicon self-aligned contact. The fabricated device exhibited a responsivity of 47 mA/W, providing an improvement over previous devices of similar dimensions, although were ultimately limited by the quality of the poly-silicon/silicon interface. A sub-micron waveguide photodiode fabrication process using electron-beam lithography was developed, which produced photodiodes with responsivities of 490 mA/W. This process was used to integrate photodiodes onto micro-ring resonators, which exhibit resonant enhanced photocurrent. The physics of this enhancement were explored, and found to produce a 50 μm long resonant photodiode of responsivity equal to that of a 3 mm long non-resonant photodiode. Lastly, the integration of such sub-micron photodiodes as functioning power monitors throughout photonic circuits was demonstrated as a means to characterize and tune micro-rings during operation.</p> / Doctor of Philosophy (PhD)

<p> This thesis contributes to the computer-aided design (CAD) of spiral inductors and LC resonators with spiral inductors exploiting full-wave electromagnetic (EM) analysis.</p> <p> The spiral inductor is widely used in radio frequency integrated circuits (RF ICs), such as low noise amplifiers (LNA) and voltage controlled oscillators (VCO). The design of spiral inductors has a direct influence on the performance of these circuits. Recently proposed optimization methods for spiral inductors are usually based on circuit models, which are computationally efficient but inaccurate compared with full-wave electromagnetic (EM) simulations.</p> <p> For the first time, we develop an optimization technique for the design of spiral inductors and LC resonators exploiting both the computational efficiency of a (cheap) circuit model and the accuracy of a full-wave EM analysis, based on geometric programming (GP) and space mapping (SM). With the new technique, we can efficiently obtain EM-validated designs with considerable improvement over those obtained with traditional optimization methods.</p> / Thesis / Master of Applied Science (MASc)

<p>With the emergence of 5G/mm-Wave communication, there is a growing need for novel front-end electromechanical devices in filtering and carrier generation applications. CMOS-MEMS resonators fabricated using state-of-the-art Integrated Circuit (IC) manufacturing processes provide a significant advantage for power, area and cost savings. In this work, a comprehensive physics-based compact model capable of capturing the non-linear behaviour and other non-idealities has been developed for MEMS resonators seamlessly integrated in CMOS. As the first large signal model for CMOS-embedded resonators, it enables holistic design of MEMS components with advanced CMOS circuits as well as system-level performance evaluation within the framework of modern IC design tools. Global Foundries 14nm FinFET (GF14LPP) Resonant Body Transistors (fRBT) operating at 11.8 GHz are demonstrated and benchmarked against this large-signal electromechanical model. </p> <p><br></p> <p>Additionally, there is a growing interest in CMOS-integrable ferroelectric materials such as Hafnium Dioxide (HfO2) and Aluminum Scandium Nitride (AlScN) for next-generation memory and computation, as well as electromechanical transduction in CMOS-MEMS devices. This work also explores the performance of 700 MHz Ferroelectric Capacitor-based resonators in the Texas Instruments HPE035 process under high-power operating conditions. Identification of previously unreported characteristics, together with the first nonlinear large signal model for integrated ferroelectric resonators, provides insights on the design of frequency references and acoustic filters using ferroelectric transducers. </p> <p><br></p> <p>Extending the range of unreleased CMOS-MEMS resonators to lower frequency using novel design, we also investigate embedded transducers in chip-scale devices for physical sensing. We have simulated and modeled the transducer coupling for low-frequency propagating modes and benchmarked their projected performance against state-of-the-art conventional MEMS sensors. A new approach to phononic crystal (PnC) Interdigitated Transducers (IDTs) is presented emulating the acoustic dispersion in conventional ICs. Unloaded quality factors up to 15,000 have been measured in $\sim$80 MHz resonators, demonstrating their capacity for resonant rotation sensing. We present a unique methodology to amplify and collimate acoustic waves using CMOS-design-rule-compliant Graded Index (GRIN) Phononic IDTs. Ultimately, the CMOS-MEMS techniques presented in this work for both RF applications and physical sensing can facilitate additional functionality in standard CMOS and emerging 3D heterogeneously integrated (3DHI) ICs with minor or no modifications to manufacturing and packaging. This enables new paradigms in next-generation communications, internet of things (IoT), and hardware security.</p>

Nanoelectromechanical systems (NEMS) play an important role in advancing high-precision sensing and high-speed computational applications due to their exceptional sensitivity and reduced size. This thesis explores the dynamic behaviors and vibrational properties of NEMS, focusing on coupled systems of molybdenum disulfide (MoS2) membrane and silicon nitride (SiNx) drumhead, and the effects of gas pressure on an MoS2 membrane resonator. Employing finite element simulations alongside theoretical modeling, the study thoroughly analyzes the coupling dynamics between MoS2 and SiNx resonators and investigates the vibrational responses of MoS2 membranes under pressure. Key achievements include the identification of vibrational modes, calculation of coupling constants, and comprehensive understanding of pressurized MoS2 membrane resonator behavior. These insights pave the way for enhancing NEMS applications in sensitive detection and resonant frequency modulation, significantly contributing to the field of nanotechnology and the development of advanced NEMS devices.

A dielectric filled cavity structure is currently being used to estimate the dielectric constant and loss factor over a wide range of frequencies of a dielectric material which fills the cavity structure [Saed, 1987]. A full field analysis is used to compute the effective complex permittivity of the sample material based on reflection coefficient measurements of the cavity structure and associated geometrical dimensions. The method has previously been used successfully to determine the dielectric constant of materials, but limitations in the Inethod have created difficulties in accurate determination of the dielectric loss factor. The effective loss in this method yields an estimate of the total cavity loss, including both the dielectric loss and that of the cavity conductor walls. In this dissertation a perturbation approach is used to separate the conductor loss from the total loss. The loss-free full-field analysis is used to determine the electric current at the conductor boundaries. This current is used to evaluate the perturbed power dissipated in the cavity walls based on known conductor properties. By subtracting the loss due to the conductor walls from the total loss measured in the structure, the dielectric loss and the resultant dielectric loss factor may be estimated. Measurements are presented for sample dielectric materials. The dielectric loss tangents computed by this new technique improve the unperturbed estimates in the microwave frequency range. / Ph. D.

Optical resonators, which confine light by resonant recirculation, serve as the basis for a wide variety of optical components. Though they appear in many geometric forms, the most effective of optical resonators show axial symmetry in at least one dimension. A popular variation that finds broad application is the dielectric sphere. Acclaimed for their high quality (Q) factor and small modal volume, spheres owe credit of these attractive features to their support of whispering gallery mode (WGM) resonances. The sensitivity of a resonance's frequency and Q to strain, temperature, and other parameters of the surrounding medium can be the basis for ultracompact modulators and sensors. Physically, WGMs are special optical modes which can be understood as light rays that orbit the equator of the sphere guided by total internal reflection. Like a smooth stone can be skipped along the surface of a pond, light can be confined to the inside of a sphere by successive reflections. To best excite WGMs, the source light should initially trace a line tangent to the sphere's circumference. But incorporating a tiny sphere with such nanometric tolerances into a practical sensor structure has its challenges and the prospects for microsphere applications have suffered because of the plight of this problem. The work in this dissertation details the fabrication and function of three new "press fit" spherical resonators. These etched fiber micro-devices were developed to meet the demand for a robust, self-integrated means of coupling light between an optical fiber and WGMs in a microsphere resonator. The etching processes have been tuned to enable secure storage of a microsphere while also providing efficient excitation and interrogation of WGMs. Furthermore, the methods have been designed to be staightforward, quick, and repeatable. Using standard etchants on common polarization-maintaining fiber with readily purchased microspheres, the press fit resonators demonstrated here can be batch-fabricated and assembled. The press fit spherical resonator offers an alignment-free and conveniently pigtailed WGM coupler that has great potential for bio-science sensing applications and studies of resonant bispheres. / Ph. D.

No description available.

Artificial magnetic materials (AMMs) are a type of metamaterials which are engineered to exhibit desirable magnetic properties not found in nature. AMMs are realized by embedding electrically small metallic resonators aligned in parallel planes in a host dielectric medium. In the presence of a magnetic field, an electric current is induced on the inclusions leading to the emergence of an enhanced magnetic response inside the medium at the resonance frequency of the inclusions. AMMs with negative permeability are used to develop single negative, or double negative metamaterials. AMMs with enhanced positive permeability are used to provide magneto-dielectric materials at microwave or optical frequencies where the natural magnetic materials fail to work efficiently. Artificial magnetic materials have proliferating applications in microwave and optical frequency region. Such applications include inversely refracting the light beam, invisibility cloaking, ultra miniaturizing and frequency bandwidth enhancing low profile antennas, planar superlensing, super-sensitive sensing, decoupling proximal high profile antennas, and enhancing solar cells efficiency, among others. AMMs have unique enabling features that allow for these important applications. Fundamental limitations on the performance of artificial magnetic materials have been derived. The first limitation which depends on the generic model of permeability functions expresses that the frequency dispersion in an AMM is limited by the desired operational bandwidth. The other constraints are derived based on the geometrical limitations of inclusions. These limitations are calculated based on a circuit model. Therefore, a formulation for permeability and magnetic susceptibility of the media based on a circuit model is developed. The formulation is in terms of a geometrical parameter that represents the geometrical characteristics of the inclusions such as area, perimeter and curvature, and a physical parameter that represents the physical, structural and fabrication characteristics of the medium. The effect of the newly introduced parameters on the effective permeability of the medium and the magnetic loss tangent are studied. In addition, the constraints and relations are used to methodically design artificial magnetic material meeting specific operational requirements. A novel design methodology based on an introduced analytical formulation for artificial magnetic material with desired properties is implemented. The synthesis methodology is performed in an iterative four-step algorithm. In the first step, the feasibility of the design is tested to meet the fundamental constraints. In consecutive steps, the geometrical and physical factors which are attributed to the area and perimeter of the inclusion are synthesized and calculated. An updated range of the inclusion's area and perimeter is obtained through consecutive iterations. Finally, the outcome of the iterative procedure is checked for geometrical realizability. The strategy behind the design methodology is generic and can be applied to any adopted circuit based model for AMMs. Several generic geometries are introduced to realize any combination of geometrically realizable area and perimeter (s,l) pairs. A realizable geometry is referred to a contour that satisfies Dido's inequality. The generic geometries introduced here can be used to fabricate feasible AMMs. The novel generic geometries not only can be used to enhance magnetic properties, but also they can be configured to provide specific permeability with desired dispersion function over a certain frequency bandwidth with a maximum magnetic loss tangent. The proposed generic geometries are parametric contours with uncorrelated perimeter and area function. Geometries are configured by tuning parameters in order to possess specified perimeter and surface area. The produced contour is considered as the inclusion's shape. The inclusions are accordingly termed Rose curve resonators (RCRs), Corrugated rectangular resonators (CRRs) and Sine oval resonators (SORs). Moreover, the detailed characteristics of the RCR are studied. The RCRs are used as complementary resonators in design of the ground plane in a microstrip stop-band filter, and as the substrate in design of a miniaturized patch antenna. The performance of new designs is compared with the counterpart devices, and the advantages are discussed.