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Theses/Dissertations

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Electrical and Computer Engineering

2017

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Articles 1 - 17 of 17

Full-Text Articles in Nanoscience and Nanotechnology

Synthesis, Transport, And Thermoelectric Studies Of Topological Dirac Semimetal Cd3as2 For Room Temperature Waste Heat Recovery And Energy Conversion, Tahereh A. Hosseini Dec 2017

Synthesis, Transport, And Thermoelectric Studies Of Topological Dirac Semimetal Cd3as2 For Room Temperature Waste Heat Recovery And Energy Conversion, Tahereh A. Hosseini

Theses and Dissertations

ABSTRACT

SYNTHESIS, TRANSPORT, AND THERMOELECTRIC STUDIES OF TOPOLOGICAL DIRAC SEMIMETAL CD3AS2 FOR ROOM TEMPERATURE WASTE HEAT RECOVERY AND ENERGY CONVERSION

by

The University of Wisconsin-Milwaukee, 2017

Under the Supervision of Professor Nikolai Kouklin

Rising rates of the energy consumption and growing concerns over the climate change worldwide have made energy efficiency an urgent problem to address. Nowadays, almost two-thirds of the energy produced by burning fossil fuels to generate electrical power is lost in the form of the heat. On this front, increasing electrical power generation through a waste heat recovery remains one of the highly promising venues of the ...


Design And Simulation Of A Miniature Cylindrical Mirror Auger Electron Energy Analyzer With Secondary Electron Noise Suppression, Jay A. Bieber Nov 2017

Design And Simulation Of A Miniature Cylindrical Mirror Auger Electron Energy Analyzer With Secondary Electron Noise Suppression, Jay A. Bieber

Graduate Theses and Dissertations

In the nanoscale metrology industry, there is a need for low-cost instruments, which have the ability to probe the structrure and elemental composition of thin films. This dissertation, describes the research performed to design and simulate a miniature Cylindrical Mirror Analyzer, (CMA), and Auger Electron Spectrometer, (AES). The CMA includes an integrated coaxial thermionic electron source. Electron optics simulations were performed using the Finite Element Method, (FEM), software COMSOL. To address the large Secondary Electron, (SE), noise, inherent in AES spectra, this research also included experiments to create structures in materials, which were intended to suppress SE backgound noise in ...


Investigating Scalable Manufacturing Of High-Conductivity Wires And Coatings From Ultra-Long Carbon Nanotubes, Pouria Khanbolouki Nov 2017

Investigating Scalable Manufacturing Of High-Conductivity Wires And Coatings From Ultra-Long Carbon Nanotubes, Pouria Khanbolouki

Mechanical Engineering ETDs

Carbon nanotubes (CNTs) are a promising candidate for next generation of electrical wirings and electromagnetic interference (EMI) shielding materials due to their exceptional mechanical and electrical properties. Wires and coatings from ultralong nanotubes that are highly crystalline, well-aligned and densely packed can achieve this goal. High-performance CNT conductors will be relatively lightweight and resistant to harsh conditions and therefore can potentially replace current conductors in many industries including aerospace, automotive, gas and oil.

This thesis investigates a new manufacturing approach, based on conventional solution coating and wire drawing methods, to fabricate high conductivity wires and coatings from ultra-long carbon nanotubes ...


Nanowire-Based Light-Emitting Diodes: A New Path Towards High-Speed Visible Light Communication, Mohsen Nami Sep 2017

Nanowire-Based Light-Emitting Diodes: A New Path Towards High-Speed Visible Light Communication, Mohsen Nami

Physics & Astronomy ETDs

Nano-scale optoelectronic devices have gained significant attention in recent years. Among these devices are semiconductor nanowires, whose dimeters range from 100 to 200 nm. Semiconductor nanowires can be utilized in many different applications including light-emitting diodes and laser diodes. Higher surface to volume ratio makes nanowire-based structures potential candidates for the next generation of photodetectors, sensors, and solar cells. Core-shell light-emitting diodes based on selective-area growth of gallium nitride (GaN) nanowires provide a wide range of advantages. Among these advantages are access to non-polar m-plane sidewalls, higher active region area compared to conventional planar structures, and reduction of threading ...


The Efficacy Of Programming Energy Controlled Switching In Resistive Random Access Memory (Rram), David Malien Nminibapiel Jul 2017

The Efficacy Of Programming Energy Controlled Switching In Resistive Random Access Memory (Rram), David Malien Nminibapiel

Electrical & Computer Engineering Theses & Disssertations

Current state-of-the-art memory technologies such as FLASH, Static Random Access Memory (SRAM) and Dynamic RAM (DRAM) are based on charge storage. The semiconductor industry has relied on cell miniaturization to increase the performance and density of memory technology, while simultaneously decreasing the cost per bit. However, this approach is not sustainable because the charge-storage mechanism is reaching a fundamental scaling limit. Although stack engineering and 3D integration solutions can delay this limit, alternate strategies based on non-charge storage mechanisms for memory have been introduced and are being actively pursued.

Resistive Random Access Memory (RRAM) has emerged as one of the ...


Optimization Of Reduced Graphene Oxide Deposition For Hydrogen Sensing Technologies, Matthew Pocta May 2017

Optimization Of Reduced Graphene Oxide Deposition For Hydrogen Sensing Technologies, Matthew Pocta

Mechanical Engineering Undergraduate Honors Theses

Graphene is known to be a key material for improving the performance of hydrogen sensors. High electrical conductivity, maximum possible surface area with respect to volume, and high carrier mobility are a few of the properties that make graphene ideal for hydrogen sensing applications. The problem with utilizing graphene is the difficulty in depositing uniform, thin layers onto substrate surfaces. This study examines a new method of optimizing graphene deposition by utilizing an airbrush to deposit both graphene oxide (GO) and reduced graphene oxide (rGO) onto glass substrates. The number of depositions were varied among samples to study the effect ...


Characterization Of Coupled Gold Nanoparticles In A Sparsely Populated Square Lattice, Roy Truett French Iii May 2017

Characterization Of Coupled Gold Nanoparticles In A Sparsely Populated Square Lattice, Roy Truett French Iii

Theses and Dissertations

Metal nanoparticles deposited in regular arrays spaced at optical wavelengths support a resonance due to a coherent coupling between localized surface plasmon mode and lattice diffraction allowing for engineering of tunable devices for use in biological sensors, nanoantennae, and enhanced spectroscopy. Techniques such as electron beam lithography, focused ion beam lithography, nanosphere lithography, and nanoimprint lithography are used for fabrication but are limited by cost, device throughput, and small deposition. Polymer soft lithography and continuous dewetting of particles is a potentially viable alternative showing promise in all of those areas. This thesis developed the fabrication of a refined hydrophilic nanoimprinted ...


Exceeding Conventional Photovoltaic Efficiency Limits Using Colloidal Quantum Dots, Gregory F. Pach Apr 2017

Exceeding Conventional Photovoltaic Efficiency Limits Using Colloidal Quantum Dots, Gregory F. Pach

Electrical, Computer & Energy Engineering Graduate Theses & Dissertations

Colloidal quantum dots (QDs) are a widely investigated field of research due to their highly tunable nature in which the optical and electronic properties of the nanocrystal can be manipulated by merely changing the nanocrystal’s size. Specifically, colloidal quantum dot solar cells (QDSCs) have become a promising candidate for future generation photovoltaic technology. Quantum dots exhibit multiple exciton generation (MEG) in which multiple electron-hole pairs are generated from a single high-energy photon. This process is not observed in bulk-like semiconductors and allows for QDSCs to achieve theoretical efficiency limits above the standard single-junction Shockley-Queisser limit. However, the fast expanding ...


Augmenting Mask-Based Lithography With Direct Laser Writing To Increase Resolution And Speed, Miles Patrick Lim Jan 2017

Augmenting Mask-Based Lithography With Direct Laser Writing To Increase Resolution And Speed, Miles Patrick Lim

Senior Projects Fall 2017

We present combined direct-laser-writing and UV Lithography in SU-8F and S1813 as a fast and flexible lithographic technique for the prototyping of functional polymer devices and pattern transfer applications. Direct laser writing (DLW), which is performed by focusing a laser through a microscope objective, is a useful alternative method for patterning photoresists with sub-micron resolution. DLW however, can be time consuming if the pattern density is high since it is a serial technique. Typically, dense patterns are made using conventional mask-based UV lithography, but these masks can be quite expensive if the resolution is high and the mask cannot be ...


Periodically Patterned Structures For Nanoplasmonic And Biomedical Applications, Akshit Peer Jan 2017

Periodically Patterned Structures For Nanoplasmonic And Biomedical Applications, Akshit Peer

Graduate Theses and Dissertations

Periodically patterned nanostructures have imparted profound impact on diverse scientific disciplines. In physics, chemistry, and materials science, artificially engineered photonic crystals have demonstrated an unprecedented ability to control the propagation of photons through light concentration and diffraction. The field of photonic crystals has led to many technical advances in fabricating periodically patterned nanostructures in dielectric/metallic materials and controlling the light-matter interactions at the nanoscale. In the field of biomaterials, it is of great interest to apply our knowledge base of photonic materials and explore how such periodically patterned structures control diverse biological functions by varying the available surface area ...


Low-Temperature Fabrication Process For Integrated High-Aspect Ratio Metal Oxide Nanostructure Semiconductor Gas Sensors, William Paul Clavijo Jan 2017

Low-Temperature Fabrication Process For Integrated High-Aspect Ratio Metal Oxide Nanostructure Semiconductor Gas Sensors, William Paul Clavijo

Theses and Dissertations

This work presents a new low-temperature fabrication process of metal oxide nanostructures that allows high-aspect ratio zinc oxide (ZnO) and titanium dioxide (TiO2) nanowires and nanotubes to be readily integrated with microelectronic devices for sensor applications. This process relies on a new method of forming a close-packed array of self-assembled high-aspect-ratio nanopores in an anodized aluminum oxide (AAO) template in a thin (2.5 µm) aluminum film deposited on a silicon and lithium niobate substrate (LiNbO3). This technique is in sharp contrast to traditional free-standing thick film methods and the use of an integrated thin aluminum film greatly ...


Advances In Chemical Vapor Deposition Growth Of Molybdenum Disulfide For Photodetectors And Flexible Electronics, Carlos Francisco De Anda Orea Jan 2017

Advances In Chemical Vapor Deposition Growth Of Molybdenum Disulfide For Photodetectors And Flexible Electronics, Carlos Francisco De Anda Orea

Open Access Theses & Dissertations

The conversion of light into electrical signals is at the basis of technologies that affect our daily lives. Applications, including video imaging, optical communications, biomedical imaging, security, night-vision, gas sensing and motion detection have reached a high level of maturity due to the development of high-performance materials, large-scale production, and integration technologies. Currently conventional photodetectors made of Silicon (Si) or III-V compounds are about to reach their maximum efficiency, and every time it is harder to get a noticeable improvement in performance of sensors based on these materials, not to mention the complicated fabrication methods to achieve just a few ...


Skynet: Memristor-Based 3d Ic For Artificial Neural Networks, Sachin Bhat Jan 2017

Skynet: Memristor-Based 3d Ic For Artificial Neural Networks, Sachin Bhat

Masters Theses

Hardware implementations of artificial neural networks (ANNs) have become feasible due to the advent of persistent 2-terminal devices such as memristor, phase change memory, MTJs, etc. Hybrid memristor crossbar/CMOS systems have been studied extensively and demonstrated experimentally. In these circuits, memristors located at each cross point in a crossbar are, however, stacked on top of CMOS circuits using back end of line processing (BOEL), limiting scaling. Each neuron’s functionality is spread across layers of CMOS and memristor crossbar and thus cannot support the required connectivity to implement large-scale multi-layered ANNs.

This work proposes a new fine-grained 3D integrated ...


Advances In Single Molecule Microscopy: Protein Characterization, Force Analysis And Fluorescence Localization, Chi-Fu Yen Jan 2017

Advances In Single Molecule Microscopy: Protein Characterization, Force Analysis And Fluorescence Localization, Chi-Fu Yen

Graduate Theses and Dissertations

Recent advances in single molecule techniques have allowed scientists to address biological questions which cannot be resolved by traditional ensemble measurements. In this dissertation, I integrate single molecule and bulk measurements to establish a direct link between copper exposure and neurotoxicity in prion disease. Furthermore, I develop a new analysis method to improve the accuracy of kinetic parameter estimation in single molecule Atomic Force Microscope (AFM) experiments. Finally, I develop a new fluorescence localization microscopy to identify the axial position of a single fluorescent object with sub-nanometer accuracy.

Prion diseases are characterized by the misfolding and oligomerization of prion protein ...


Mems Tunable Infrared Metamaterial And Mechanical Sensors, Qiugu Wang Jan 2017

Mems Tunable Infrared Metamaterial And Mechanical Sensors, Qiugu Wang

Graduate Theses and Dissertations

Sub-wavelength resonant structures open the path for fine controlling the near-field at the nanoscale dimension. They constitute into macroscopic “metamaterials” with macroscale properties such as transmission, reflection, and absorption being tailored to exhibit a particular electromagnetic response. The properties of the resonators are often fixed at the time of fabrication wherein the tunability is demanding to overcome fabrication tolerances and afford fast signal processing. Hybridizing dynamic components such as optically active medium into the device makes tunable devices. Microelectromechanical systems (MEMS) compatible integrated circuit fabrication process is a promising platform that can be merged with photonics or novel 2D materials ...


Flexible, Photopatterned, Colloidal Cdse Semiconductor Nanocrystal Integrated Circuits, Franklin Scott Stinner Jan 2017

Flexible, Photopatterned, Colloidal Cdse Semiconductor Nanocrystal Integrated Circuits, Franklin Scott Stinner

Publicly Accessible Penn Dissertations

As semiconductor manufacturing pushes towards smaller and faster transistors, a parallel goal exists to create transistors which are not nearly as small. These transistors are not intended to match the performance of traditional crystalline semiconductors; they are designed to be significantly lower in cost and manufactured using methods that can make them physically flexible for applications where form is more important than speed. One of the developing technologies for this application is semiconductor nanocrystals.

We first explore methods to develop CdSe nanocrystal semiconducting “inks” into large-scale, high-speed integrated circuits. We demonstrate photopatterned transistors with mobilities of 10 cm2/Vs on ...


Design And Synthesis Of Gold Nanoparticle Contrast Agents For Atherosclerosis Imaging With Computed Tomography, Peter Chhour Jan 2017

Design And Synthesis Of Gold Nanoparticle Contrast Agents For Atherosclerosis Imaging With Computed Tomography, Peter Chhour

Publicly Accessible Penn Dissertations

Cell tracking offers the opportunity to study migration and localization of cells in vivo, allowing investigations of disease mechanisms and drug efficacy. Monocytes play a key role in the progression of atherosclerotic plaques in the coronary arteries. While x-ray computed tomography (CT) is commonly used to clinically assess coronary plaque burden, cell tracking with CT is mostly unexplored. The establishment of monocyte cell tracking tools would allow for the direct investigation of gene and drug therapies aimed at monocyte recruitment in atherosclerosis. In this thesis, we present the design and optimization of gold nanoparticles as CT contrast agents for cell ...