Engineering Commons^™

Series-Fed Aperture-Coupled Microstrip Antennas And Arrays, Bojana Zivanovic

USF Tampa Graduate Theses and Dissertations

The focus of this dissertation is on the development and circuit modeling of planar series-fed, linear- and circular-polarized microstrip aperture-coupled antennas and N-element arrays operating in C-band. These arrays were designed to be used as part of airborne or land-based frequency-hopped communication systems. One of the main objectives of this work was to maintain a constant beam angle over the frequency band of operation. In order to achieve constant beam pointing versus frequency, an anti-symmetric series-fed approach using lumped-element circuit models was developed. This series feed architecture also balances the power radiated by each element in the N-element arrays.

The …

Opportunistic Scheduling And Cooperative Relaying In Wireless Networks, Yufeng Wang

USF Tampa Graduate Theses and Dissertations

The demand for ever larger, more efficient, reliable and cost effective communication networks necessitates new network architectures, such as wireless ad hoc networks, cognitive radio, relaying networks, and wireless sensor networks. The study of such networks requires a fundamental shift from thinking of a network as a collection of independent communication pipes, to a multi-user channel where users cooperate via conferencing, relaying, and joint source-channel coding.

The traditional centralized networks, such as cellular networks, include a central controller and a fixed infrastructure, in which every node communicates with each other via a centralized based station (BS). However, for a decentralized …

Modified Statistical Dynamical Diffraction Theory : A Novel Metrological Analysis Method For Partially Relaxed And Defective C Doped Si And Sige Heterostructures, Paul Kenneth Shreeman

Legacy Theses & Dissertations (2009 - 2024)

The statistical dynamical diffraction theory, which has been initially developed by late Kato remained in obscurity for many years due to intense and difficult mathematical treatment that proved to be quite challenging to implement and apply. With assistance of many authors in past (including Bushuev, Pavlov, Pungeov, and among the others), it became possible to implement this unique x-ray diffraction theory that combines the kinematical (ideally imperfect) and dynamical (the characteristically perfect diffraction) into a single system of equations controlled by two factors determined by long range order and correlation function within the structure. The first stage is completed by …

Generality In Nanotechnologies And Its Relationship To Economic Performance, Fernando Gomez Baquero

Legacy Theses & Dissertations (2009 - 2024)

In the history if economic analysis there is perhaps no more important question than the one of how economic development is achieved. For more than a century, economists have explored the role of technology in economic growth but there is still much to be learned about the effect that technologies, in particular emerging ones, have on economic growth and productivity. The objective of this research is to understand the relationship between nanotechnologies and economic growth and productivity, using the theory of General Purpose Technology (GPT)-driven economic growth. To do so, the Generality Index (calculated from patent data) was used to …

Development Of Iii-V P-Mosfets With High-Kappa Gate Stack For Future Cmos Applications, Padmaja Nagaiah

Legacy Theses & Dissertations (2009 - 2024)

As the semiconductor industry approaches the limits of traditional silicon CMOS scaling, non-silicon materials and new device architectures are gradually being introduced to improve Si integrated circuit performance and continue transistor scaling. Recently, the replacement of SiO2 with a high-k material (HfO2) as gate dielectric has essentially removed one of the biggest advantages of Si as channel material. As a result, alternate high mobility materials are being considered to replace Si in the channel to achieve higher drive currents and switching speeds. III-V materials in particular have become of great interest as channel materials, owing to their superior electron transport …

Al/Cuxo/Cu Memristive Devices : Fabrication, Characterization, And Modeling, Nathan Mcdonald

Legacy Theses & Dissertations (2009 - 2024)

Memristive devices have become very popular in recent years due to their potential to dramatically alter logic processing in CMOS circuitry. Memristive devices function as electrical potentiometers, allowing for such diverse applications as memory storage, multi-state logic, and reconfigurable logic gates.

Graphene-Based Post-Cmos Architecture, Sansiri Tanachutiwat

Legacy Theses & Dissertations (2009 - 2024)

The semiconductor industry relies on CMOS technology which is nearing its scaling limitations. In order to continue the historical growth rate of the device density of digital logic chips, novel nanomaterials and nanodevices will need to be developed.

Virus Capsids As Nanoscale Delivery Vessels Of Photoactive Compounds For Site-Specific Photodynamic Therapy, Brian Alexander Cohen

Legacy Theses & Dissertations (2009 - 2024)

The research presented in this work details the use of a viral capsid as an addressable delivery vessel of photoactive compounds for use in photodynamic therapy. Photodynamic therapy is a treatment that involves the interaction of light with a photosensitizing molecule to create singlet oxygen, a reactive oxygen species. Overproduction of singlet oxygen in cells can cause oxidative damage leading to cytotoxicity and eventually cell death. Challenges with the current generation of FDA-approved photosensitizers for photodynamic therapy primarily stem from their lack of tissue specificity. This work describes the packaging of photoactive cationic porphyrins inside the MS2 bacteriophage capsid, followed …

Micropatterned Electrospun Nanofibrous Substrates As Scaffolds For Engineered Salivary Glands, David Alexander Soscia

Legacy Theses & Dissertations (2009 - 2024)

The salivary gland is a complex organ exhibiting a branching, 3-dimensional structure made up of acinar (saliva-producing), and ductal (saliva transporting and modifying) epithelial cells. The high surface area of the gland allows it to efficiently provide the mouth with saliva, maintaining oral cleanliness and comfort. Salivary gland hypofunction, a significant clinical problem often caused by the autoimmune disease Sjögren's syndrome or head and neck radiation for cancer patients, affects millions of Americans and is characterized by a loss of function of salivary gland acinar cells. Chronic xerostomia, or dry mouth, arises as a result of salivary gland hypofunction and …

Bioengineering Embryonic Microenvironment For Exploring Stem Cell-Breast Cancer Cell Interactions, Nurazhani Abdul Raof

Legacy Theses & Dissertations (2009 - 2024)

Embryonic stem (ES) cells and breast cancer cells share similar signaling pathways that allow cells to proliferate and differentiate. However, signaling molecules in cancer cells are misexpressed. Cell microenvironments that consist of many factors such as soluble factors, extracellular matrices, and neighboring cells, play a pivotal role in determining cellular fate. The exposure of ES cell microenvironments to cancer cells may address the missing components in the tumor microenvironment, which could inhibit tumorigenesis or reprogram cancer cells into a less invasive phenotype. In this thesis, in vitro ES cell microenvironments have been engineered three-dimensionally via alginate hydrogel encapsulation and patterned …

Measurement Of Electron Spin Transport In Graphene On 6h-Silicon Carbide(0001), Joseph Abel

Legacy Theses & Dissertations (2009 - 2024)

The focus of this thesis is to demonstrate the potential of wafer scale graphene spintronics. Graphene is a single atomic layer of sp2-bonded carbon atoms that has high carrier mobilities, making it a desirable material for future nanoscale electronic devices. The vision of spintronics is to utilize the spin of the electron to produce novel high-speed low power consuming devices. Materials with long spin relaxation times and spin diffusion lengths are needed to realize these goals. Graphene is an ideal material as it meets these requirements and is amenable to planar device geometries.

Evaluation Of Chemical Mechanical Planarization (Cmp) For The Removal Of Surface Defects In Extreme Ultraviolet Lithography (Euvl) Mask Substrates, Bradley Halligan Wood

Legacy Theses & Dissertations (2009 - 2024)

A modified CMP process was investigated and developed with the goal of removing surface defects (nanoscale depressions or `pits') from quartz mask blank substrates. Initially, quartz glass wafers were evaluated to observe surface roughness and defect introduction due to low down-force CMP processing. Following analysis of quartz glass wafers subjected to such processing it was determined that a CMP-based processing for pit removal of maskblank substrates was potentially viable. Consequently, a specially-designed mask carrier for investigating and developing CMP-based defect removal from EUV maskblank substrates was mounted on a Strasbaugh 6DS-SP CMP laboratory tool. A series of experiments was performed …

Development Of A Gas-Based Spectral Filter For Carbon Dioxide Laser Produced Plasma Extreme Ultraviolet Sources, Chimaobi Mbanaso

Legacy Theses & Dissertations (2009 - 2024)

Currently, extreme ultraviolet (EUV) lithography is a promising next generation lithography technique for enabling the scaling of device features beyond 22 nm. Out-of-band radiation in EUV exposure tools remains one of the critical issues that must be addressed before the implementation of this lithography technique for high volume manufacturing. Laser produced plasmas which use a carbon dioxide (CO₂) drive laser pulse are more likely to be used to generate EUV radiation because of their scalability to higher source power. The out-of-band spectrum at the intermediate focus of EUV sources that use a CO₂ laser produced plasma is …

Development Of An Industrial Fabrication Process For Next Generation, Thinner And Larger Crystalline Silicon (C-Si) Wafer-Based Solar Cells, Anh Viet Nguyen

Legacy Theses & Dissertations (2009 - 2024)

The world's solar cell production has grown rapidly and steadily with an annual average of 30% over the last two decades. Single and micro-crystalline silicon solar cells have been the major reason for this production increase. In 2009, silicon-based solar cells comprised almost 90% of worldwide photovoltaic module shipments.

Experimental And Theoretical Analysis Of Strain Engineered Aluminium Nitride On Silicon For High Quality Aluminium(X)Indium(Y)Gallium(1-X-Y)Nitride Epitaxy, Mihir Hemant Tungare

Legacy Theses & Dissertations (2009 - 2024)

III-Nitrides on Si are of great technological importance due to the availability of large area, epi ready Si substrates and the ability to heterointegrate with mature silicon micro and nanoelectronics. The major roadblock with realizing this is the large difference in thermal expansion coefficients and lattice constants between the two material systems. A novel technique developed in our research lab shows the potential of simultaneous and substantial reduction in dislocation and crack density in GaN on Si (111). Research undertaken in the current doctoral dissertation, validates the superior GaN quality on Si obtained using our technique and determines the factors …

Plasma Enhanced Atomic Layer Deposition Of Cu Seed Layers At Low Process Temperatures, Jiajun Mao

Legacy Theses & Dissertations (2009 - 2024)

In conventional Cu interconnect fabrication, a sputtered copper seed layer is deposited before the electrochemically deposited (ECD) copper plating step. However, as interconnect dimensions scale down, non-conformal seed layer growth and subsequent voiding of metallized structures is becoming a critical issue. With its established excellent thickness controllability and film conformality, atomic layer deposition (ALD) is becoming an attractive deposition approach for the sub-24nm fabrication regime. However, in order to achieve a smooth and continuous seed layer deposition, a low process temperature (below 100oC) is needed, given the tendency of Cu agglomeration at elevated temperature. In this research, plasma enhanced ALD …

(In, Al) Co-Doped Zinc Oxide As A Novel Material System For Quantum-Well Multilayer Thermoelectrics, Sean C. Teehan

Legacy Theses & Dissertations (2009 - 2024)

Waste heat recovery from low efficiency industrial processes requires high performance thermoelectric materials to meet challenging requirements. The efficiency such a device is quantified by the dimensionless figure of merit ZT=S2σT/қ, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature and қ is the thermal conductivity. For practical applications these devices are only cost-effective if the ZT is higher than 2.

The Influence Of Copper Substrate Orientation On Graphene Growth, Zachary Robert Robinson

Legacy Theses & Dissertations (2009 - 2024)

This dissertation is focused on determining the influence of the copper substrate on graphene grown by \ac{CVD}. Graphene, which can be grown in single atomic layers on copper substrates, has potential applications in future electronic devices. One of the key issues for the use of graphene grown by chemical vapor deposition for device applications is the influence of defects on the transport properties of the graphene. For instance, growth on metal foil substrates results in multi-domain graphene growth because the foil substrates themselves have a variety of different surface terminations. Therefore, they don't serve as a very good template for …

Molecular Vapor Deposition Of Organosilanes, Sarah Kirsten Goulet

Legacy Theses & Dissertations (2009 - 2024)

Current strategies for low temperature bonding (<300 C) and 3D integration employ polymer interfaces (1-3 um) with low thermal conductivity which can result in poor heat transfer between bonded elements. The introduction of thinner interfaces to improve heat transfer is desirable; however, deposition of thin polymer films (<100 nm) for bonding applications can lead to reduced film uniformity and negatively affect bonding strength. Self-assembled monolayer (SAM) chemistries provide a potential solution and can yield nanometer control of the interfacial layer thickness without a significant effect on surface roughness. Siloxanes are one available option to realize these nanometer thin reactive layers. Due to their propensity to crosslink and form multilayers, careful control of the reaction conditions is required. Considering this, we have evaluated the molecular vapor deposition of siloxane precursors to generate molecular layers with reactive end-groups for potential use in bonding applications. Film stability, morphology, thickness, and composition were monitored after deposition using atomic force microscopy, ellipsometry and x-ray photoelectron spectroscopy.

Ensuring The Effectiveness Of Information Security Policy : The Development And Validation Of An Information Security Policy Model, Vivid Vicki Chen

Legacy Theses & Dissertations (2009 - 2024)

The purpose of this dissertation is to develop and test a conceptual model of an Information Security Policy (ISP) and to measure the benefits that accrue to organizations that implement and deploy such policies. As a result of rapid changes in technology, the importance of computer Information Security Policy (ISP) has increased dramatically. In recent decades, governments and private enterprises have increasingly come to store ever greater amounts of information on computers and on networks. Unfortunately, storing information in this manner not only makes firms engaged in cutting-edge technology vulnerable to hackers, but may also jeopardize customer / employee relations, …

A Novel Fabrication Technique For Three-Dimensional Nanostructures, Ravi Kiran Bonam

Legacy Theses & Dissertations (2009 - 2024)

Three dimensional micro- and nano-structures are commonly used in the field of Photonics, Optoelectronics, Sensors and Biological applications. Although numerous physical models are developed, a major challenge has been in their fabrication which is commonly limited to conventional layer-by-layer techniques. In this dissertation, a novel method for fabricating three dimensional structures using Electron Beam Lithography (EBL) will be presented.

The Development And Simulation Of Piezoelectric Surface Acoustic Wave Devices For Euv Mask Particle Removal, Anthony Rae Davis

Legacy Theses & Dissertations (2009 - 2024)

Extreme Ultraviolet Lithography (EUVL) is a critical semiconductor fabrication process which uses 13.5 nanometer wavelength light reflected from a mask to print features on various wafers used for IC fabrication. An extensive amount of research is currently underway to make EUVL prevalent in efforts to allow for efficient sub-22 nm feature size fabrication. A number of challenges must be overcome before EUVL usage becomes feasible in terms of cost, wafer output, reliability, and throughput. One notable challenge in EUVL is the removal of mask contamination. EUV masks are required to be free of contamination to ensure precise feature printing. Particles …

Detailed Modeling Of Soot Size Distribution Evolution And Pollutant Formation Inside Aircraft And Diesel Engines, Chowdhury Golam Moniruzzaman

Legacy Theses & Dissertations (2009 - 2024)

Combustion emission of soot and pollutant gas species contributes to poor regional air quality near emission sources and to climate change. It is important to understand the formation mechanism and time evolution of these pollutants inside the combustion engine, through detailed modeling of combustion chemistry and microphysics as well as comparison with observation. In this thesis, two multi-zone gas parcel combustion engine models, one for aircraft engines and another for diesel engines, have been developed to study soot size distribution evolution and pollutant formation inside the engines as well as emissions. The models take into account size-resolved (sectional) soot aerosol …

Study Of The Dielectric Function Of Graphene From Spectroscopic Ellipsometry And Electron Energy Loss Spectroscopy, Florence Joan Nelson

Legacy Theses & Dissertations (2009 - 2024)

For more than 60 years, semiconductor research has been advancing up the periodic table. The first transistor was made from germanium. This later gave way to silicon-based devices due to the latter's ability to form an excellent interface with thermally-grown oxide. Now for the last ~8 years, the focus has moved up one more row to carbon for post-CMOS devices in order to comply with the scaling limitations of Moore's law. However, for each of these, the measurements of film properties and dimensions have always been required for technological applications. These measurement methods often incorporate the use of light or …

Surface Potential Measurements Of Reconfigurable P-N Junctions In Graphene, Yunfei Wang

Legacy Theses & Dissertations (2009 - 2024)

Manipulation and control of electron current in a graphene p-n junction (e.g. electron waveguiding, reflection, focusing) is directly determined by the spatial gradient of the Fermi level across the junction. Sharp Fermi level gradients are associated with negative index `lensing' of electrons in graphene while broader gradients are predicted to form reflective boundaries. Quantitative metrology of the Fermi level gradient at p-n junctions is thus essential to determine device performance, validate models for device design and switch architectures, and quantitatively determine the impact of defects on device function and leakage.

Student Contextualization In The History Classroom : The Roles Of Cognitive Apprenticeship And Teacher Epistemology, Tammy Lynn Clark

Legacy Theses & Dissertations (2009 - 2024)

Abstract

Materials Engineering For Near-Infrared Light Emission From Silicon Compatible Mos Structures, Himani Suhag Kamineni

Legacy Theses & Dissertations (2009 - 2024)

Silicon-based photonics requires several components, such as a light source, an amplifier/waveguide to transfer the signal, and a photodetector to detect the signal. The motivation for using these silicon-based technologies in photonics applications is two-fold: economic advantages offered by the compatibility with mature silicon IC manufacturing and its excellent material properties for photonic devices (high thermal conductivity, high optical damage threshold, etc.). One of the major challenges in the realization of this technology is the Si-based light source. Because of its indirect bandgap, silicon has very inefficient band-to-band radiative electron-hole recombination. To overcome this obstacle, tremendous research efforts have been …

A Novel Control Design Approach For Sever Subsystems: The Concept Of Active Disturbance Rejection And A Case Study, John Ping, Zhiqiang Gao, Rahul Khanna

Electrical and Computer Engineering Faculty Publications

No abstract provided.

Correction Of An Augmentation Bound Analysis For Parallel Real-Time Tasks, Abusayeed Saifullah, Kunal Agrawal, Chenyang Lu, Christopher Gill

All Computer Science and Engineering Research

This paper proposes some significant corrections in a recent work of Lakshmanan et al on parallel task scheduling. Lakshmanan et al have proposed a transformation of parallel tasks into sequential tasks, and have claimed a resource augmentation bound of 3:42 for partitioned deadline monotonic (DM) scheduling of the transformed tasks. We demonstrate that their analysis for resource augmentation bound is incorrect. We propose a different technique for task transformation that requires a resource augmentation bound of 5 for partitioned DM scheduling.

Real-Time Scheduling Of Parallel Tasks Under A General Dag Model, Abusayeed Saifullah, David Ferry, Chenyang Lu, Christopher Gill

All Computer Science and Engineering Research

Due to their potential to deliver increased performance over single-core processors, multi-core processors have become mainstream in processor design. Computation-intensive real-time systems must exploit intra-task parallelism to take full advantage of multi-core processing. However, existing results in real-time scheduling of parallel tasks focus on restrictive task models such as the synchronous model where a task is a sequence of alternating parallel and sequential segments, and parallel segments have threads of execution that are of equal length. In this paper, we address a general model for deterministic parallel tasks, where a task is represented as a DAG with different nodes having …