Particle strikes on microelectronic circuits lead to undesirable current transients on the circuit node due to charge generation and charge collection processes. Typically, TCAD tools are used to examine charge collection process after particle strikes and provide an insight into the various charge collection mechanisms. Since the charge collected on a circuit node is also affected by its circuit and layout parameters, and the presence of multiple transistors within a certain distance, on-chip characterization of charge collection becomes desirable for advanced technologies. The focus of this thesis is on the design of an on-chip self-triggered charge collection measurement circuit technique to experimentally quantify single-event charge collection process for deep sub-micron technologies. Simulation results on UMC 40nm technology show a maximum measurement resolution of ~5 fC for the circuit.

Networked multi-agent systems consist of a set of agents that exchange information through a medium referred to as the network. The agents in the networked system are tasked with achieving certain group objectives. These group objectives are typically decomposed into constituent objectives that require coordination among the individual agents through distributed algorithms. Two fundamental constituent objectives are consensus and synchronization. Due to the large-scale, distributed, and dynamic nature of many networked multi-agent systems, the most effective and applicable distributed consensus and synchronization algorithms are those that use purely local strategies. When using algorithms based on purely local strategies, the agents make decisions and act based only on their sensor measurements, calculations, dynamics, and direct interactions with neighbors in the network. No global information is shared or assumed to be known. Instead, information is disseminated within the network in an iterative or diffusive manner. While the last decade has seen a surge of research in the cooperative control of networked multi-agent systems, the issue of security has just recently begun to be explored. Much of the existing research focuses on detection and identification of compromised nodes and network attacks, which requires nonlocal information. Such global information may not be available, rendering these techniques inapplicable. This dissertation introduces consensus and synchronization algorithms using purely local strategies that are resilient to the adversarial influence of compromised nodes in the network. Various threat models are defined to model the behavior of compromised agents, along with scope of threat assumptions that define the scope of interactions allowed between compromised and uncompromised nodes. The efficacy of the consensus and synchronization algorithms is analyzed under the assumptions defined by the adversary models. For this analysis, a recently introduced graph theoretic metric, network robustness, is refined and shown to be the key property for characterizing the network topological conditions required for the consensus and synchronization algorithms to succeed. Several important properties of robust networks are provided and several algorithms for determining the robustness of a network are given.

Chemical-vapor-deposited (CVD) diamond is an excellent electron emission material due to its low electron affinity, robust mechanical and chemical properties, high thermal conductivity, and ability to withstand high temperature and radiation. Nanocrystalline diamond, also known as nanodiamond, is an emerging form of CVD diamond which vastly expanding its applicability in vacuum electronics. Apart from the assets of the conventional CVD diamond, it possesses certain distinct properties which include smaller grain-size, high volume density of grain-boundaries, smoother surface morphology, n-type dopant incorporation and increased sp2-carbon content. However, the utilization of nanodiamond in vacuum micro/nanoelectronics has been limited by the complexity associated with its process integration. The purpose of my research is to develop a reliable process technique to fabricate efficient nanodiamond lateral electron emission devices operable at low voltage with high emission current for applications in vacuum microelectronics and integrated-circuits. To achieve this goal, first, a well-controlled process to realize useful and potential nanodiamond electron emitter structures in array configurations using electron beam lithography (EBL) and plasma etching techniques has been developed. Detail study includes optimization of processing parameters for EBL, metal-mask deposition and nanodiamond dry etching. The main part of the research includes the application of these recently developed process techniques for the design, fabrication and characterization of micro/nanopatterned nanodiamond lateral field emission devices which include sub-micron gap two-terminal and multifinger three-terminal structures. 140-fingered nanodiamond lateral diode has been achieved for the first time with 300nm interelectrode distance. On the other hand, the three-terminal structure is composed of 140 finger-like emitters with integrated anode and gate, which also has never been reported before. The electrical characteristics of these fabricated nanodiamond vacuum lateral field emission devices demonstrated promising behavior with very low turn-on voltage with high and stable emission current. It has also been observed for the first time that three emission mechanisms dominated at different potential levels. The three-terminal structure showed anode current enhancement and suppression behavior by changing gate bias. These developments in the field of nanotechnology signify the integration of vacuum electronics with the well-established IC process techniques favorable for high-speed and high-power, IC-compatible, extreme-environment vacuum micro/nanoelectronics applications.

Nanoporous dielectric and metallic materials have recently attracted a great deal of attention for chemical and biological sensing applications. Compared to conventional solid material based sensors, porous materials provide nanoscale surface morphology and an increased internal surface area for molecule binding enabling improved sensing performance. Layered structures have been demonstrated to be excellent candidates for the fabrication of optical sensors due to their ability to localize light in regions where molecules are bound. The band structures of these layered media can be systematically designed and characterized by properly choosing design parameters, including material, refractive index, dimension, and periodicity. In this work, the advantages of nanoscale porous materials were combined with layered optical structures to achieve compact, cost-effective, and highly reproducible sensing substrates with improved sensing performance. In particular, a porous silicon (PSi) membrane waveguide was first investigated. By properly choosing design parameters including pore size, porosity, and mode order, optimized PSi waveguides with significantly improved molecular detection sensitivity were achieved. Second, a dual mode sensing platform combining refractive index and surface enhanced Raman scattering (SERS) based sensing, and capable of both quantifying and identifying captured molecules, was demonstrated based on a PSi interferometer coated with gold nanoparticles (Au NPs). Enhanced SERS signal intensity was achieved by using a PSi waveguide instead of the simple interferometer design to increase the intensity of the electric field at the surface in the region of the Au NPs. Third, an easy to fabricate and effective SERS substrate based on nanoporous gold (NPG) was investigated. This SERS substrate utilizes both localized and propagating surface plasmon effects on NPG to significantly enhance the SERS signal. Ultra high enhancement factors were demonstrated by properly tuning the grating parameters and pore openings.

Radiation-induced soft errors are becoming a dominant reliability-failure mechanism in modern CMOS technologies. In nanometer technologies, the effects are not limited to the storage elements of a digital system, but also include vulnerabilities in the combinational logic. Reliability-aware synthesis has emerged as a method to mitigate the effects of soft errors in combinational logic. Few studies have focused on the inherent impact that logic synthesis algorithms have on circuit topology, and therefore reliability. This dissertation investigates the impact that area and delay optimizations, computational effort, and standard cell availability have on the error propagation probability of individual circuit nodes. Additionally, this work identifies circuit characteristics that can be used during synthesis that help in choosing the most reliable circuit implementation. Finally, an approach to minimize circuit vulnerability based on cell selection is introduced.

This dissertation focuses on the study of electron field emission from chemical vapor deposition (CVD) nanodiamond and the development of sub-micron gap lateral nanodiamond vacuum field emission diodes. A procedure was developed for optimizing nanodiamond film for fine lithography patterning and two procedures were developed for incorporating electron beam lithography (EBL) into the device design and fabrication. The successful fabrication of smooth nanodiamond films with grain sizes as small as ~10 nm and the achievement of sub-volt turn-on, sub-micron gap delineation for varied lateral diode cathode configurations are reported. To identify the best nanodiamond film structure for use as an emitter material substrate, the underlying conduction mechanisms were discussed first. A collection of research on nitrogen-incorporated nanodiamond supports the existence of a hybrid nanostructure, reminiscent of our past reported MIM model, for low field emission. Practical CH4/H2-based chemical vapor deposition processing was applied to define various morphologies of diamond thin-film configurations followed by an analysis of the macroscopic field emission performance of each film as compared to the corresponding changes in binding energy and sp2/sp3 content. X-ray photoelectron Spectroscopy (XPS) and Raman spectroscopy were used for monitoring the deviations across the various diamond film configurations. Sub-micron emission gap lateral field emission diodes derived from the optimized nanodiamond provide an alternative means of accomplishing electronics that operate at low voltages. In this work, electron beam lithography was introduced for structure definition on CVD-diamond. Processes were developed to fabricate laterally arranged nanodiamond field emission diodes using EBL patterning. The sub-micron gap delineation showed excellent uniformity for different cathode configurations. A ~0.6 V turn-on was observed as the anode-cathode inter-electrode distance was scaled from 1.5 µm down to 500 nm. The effect of changing the anode-cathode gap was observed in I-V characteristics, with a clear deviation from Fowler-Nordheim tunneling emission as the anode-cathode distance was reduced. Reducing the inter-electrode spacing to the sub-micron range offers new and exciting opportunities for nanodiamond lateral device applications due to the high field strengths that can be achieved at low applied bias. The unique characteristics of the devices include interesting non-Fowler-Nordheim emission behavior that indicate a lowered potential barrier for field-enhanced thermionic emission and space charge limiting current at the diamond-vacuum interface.

Functional magnetic resonance imaging (fMRI) is a non-invasive imaging technique that has emerged as a powerful tool to identify the brain regions involved in cognitive processes. FMRI offers spatial and temporal resolutions adequate to measure the location, amplitude and timing of brain activity. FMRI data are commonly analyzed voxel-by-voxel using linear regression models (statistical parametric mapping). This requires information about stimulus timing and assumptions about the shape and timing of the hemodynamic response. This approach may be too restrictive to capture the broad range of possible brain activation patterns in space and time and across subjects. This dissertation presents a multivariate data-driven approach using self-organizing maps that overcome the aforementioned limitations. A self-organizing map is a topology-preserving artificial neural network model that transforms high-dimensional data into a low-dimensional map of output nodes using unsupervised learning. This dissertation proposes novel graph-based visualizations of self-organizing maps for extracting fine spatiotemporal patterns of brain activities from fMRI data to measure relative timings of brain responses. This approach was employed to identify voxels responding to the task and detect differences as small as 28 ms in the timings of brain responses in visual cortex. It outperformed other common techniques for voxel selection including independent component analysis, voxelwise univariate linear regression analysis and a separate localizer scan. This was verified by observing a statistically strong linear relationship between induced and measured timing differences. The approach was also used to correctly identify and classify task-related brain areas in an fMRI reaction time experiment involving a visuo-manual response task. In summary, the graph-based visualizations of self-organizing maps help in advanced visualization of cluster boundaries in fMRI data, thereby enabling the separation of regions with small differences in the timings of their brain responses and helping to measure relative timings of brain responses.

Hydrogen produces variability in the radiation response of integrated circuits, whether incorporated in the oxide or present as a gas. The presence of molecular hydrogen can increase interface trap buildup and alter dose rate response. Defects with hydrogen incorporated in the oxide during processing can suppress interface trap buildup at elevated temperatures. This thesis explores the reactions of hydrogenous species at common oxide defects and the mechanisms that explain radiation-induced interface trap formation and annealing, focusing on the effects of temperature, molecular hydrogen concentration, and dose rate. Density functional theory (DFT) calculations identify defects likely to be present in common thermal oxides and provide energy barriers for reactions at those defects. Proton release mechanisms and defect interactions under a variety of conditions are identified that provide insight into enhanced degradation in the presence of molecular hydrogen, irradiation at elevated temperatures, and dose rate effects. These mechanisms are implemented in a numerical model that simulates interface trap buildup in a 1-D slice of oxide and silicon using the estimates for defect concentrations and energy barriers from the DFT calculations. The results provide insight into which reactions have a significant impact on interface trap density under a variety of conditions; the predictions are compared to experimental data. The results demonstrate how proton loss reactions can limit the supply of protons at the interface and suppress interface trap buildup at elevated temperature.

Key aspects of the total-ionizing dose (TID) response of advanced complementary metaloxidesemiconductor (CMOS) technologies are examined. As technology scales down, stress can strongly affect radiation-induced leakage currents in ways that are difficult to predict in advance of detailed characterization and modeling of the responses of devices across a range of representative geometries. Quantifying the variability and the dependence on design parameters is essential to determine the significance of variability in the circuit design and lot-acceptance processes. Doping generally increases as devices become smaller for planar CMOS devices therefore technology scaling trends for TID appear to be favorable going forward, at least until device dimensions become so small that random dopant fluctuation begin to dominate the variability in response. The high body doping in partially depleted silicon on insulator (SOI) devices results in TID insensitivity, however doping in other advanced CMOS devices such as fully depleted SOI and FinFETs will play a role in the TID sensitivity, particularly in cases where lightly-doped regions are used.

QoS Routing