Nanoscience and Nanotechnology Commons^™

Designing Enhanced Nonlinearity In Plasmonic Devices With Epsilon-Near-Zero Films, Kevin Tran Le

Electrical Engineering and Computer Science (MS) Theses

The growing demand for energy-efficient optical information processing motivates compact nonlinear photonic devices that can operate at low power. Silicon photonics is a mature platform for linear optical functions, but nonlinear operation remains challenging because of its weak Kerr response, two-photon absorption at telecommunication wavelengths, and limited compatibility with deeply subwavelength plasmonic confinement. This thesis computationally investigates epsilon-near-zero thin films integrated into plasmonic waveguide architectures as a route toward stronger light–matter interaction in compact nonlinear devices.

Two waveguide geometries are examined: a hybrid metal-insulator-metal plasmonic slab waveguide incorporating an ultrathin indium tin oxide epsilon-near-zero layer (5–50 nm), and a dielectric-loaded …

Advanced Nested Coaxial Thin-Film Zno Nanostructures Synthesized By Atomic Layer Deposition For Improved Sensing Performance, Pengtao Lin, Lari S. Zhang, Kai Zhang, Helmut Baumgart

Electrical & Computer Engineering Faculty Publications

We report a new synthesis method for multiple-walled nested thin-film nanostructures by combining hydrothermal growth methods with atomic layer deposition (ALD) thin-film technology and sacrificial films, thereby increasing the surface-to-volume ratio to improve the sensing performance of novel ZnO gas sensors. Single-crystal ZnO nanorods serve as the core of the nanostructure assembly and were synthesized hydrothermally on fine-grained ALD ZnO seed films. Subsequently, the ZnO core nanotubes were coated with alternating sacrificial coaxial 3D wrap-around ALD Al2O3 films and ALD ZnO films. Basically, the center nanorod was coated with an ALD 3D wrap-around Al₂O₃ sacrificial layer to realize a nested …

Self-Assembly Of Exfoliated Graphene Flakes As Anticorrosive Coatings For Additive Manufactured Steels, Kaleb Hood, Wen Qian, Yi Xia, Savannah Krupa, Annie Dao, Sarah Ahmed, Samuel Olson, Nam Nguyen, Joseph A. Turner, Jun Jiao

Department of Mechanical and Materials Engineering: Faculty Publications

This study demonstrates the feasibility of using liquid exfoliation of expandable graphite into multilayer exfoliated graphene flakes (EGFs) to form a self-assembled thin film on an air–water interface. The film can coat the surface of additive manufactured (AM) steel substrates to enhance surface properties, specifically AM 316 stainless-steel (AM316), AM 8620 steel (AM8620), and samples of the same alloys made by conventional manufacturing (CM) processes. Liquid exfoliation offers a high yield route for an EGF coating that can cover up to 95% of the sample surface with a single application. The thin, flexible EGFs can coat a rough AM metal …

Photoassisted Nanoscale Memory Resistors, Amir Shariffar

Graduate Theses and Dissertations

Memristors or memory resistors are promising two-terminal devices, which have the potential to revolutionize current electronic memory technologies. Memristors have been extensively investigated and reported to be practical devices, although they still suffer from poor stability, low retention time, and laborious fabrication processes.

The primary aim of this project was to achieve a device structure of quantum dots or thin films to address a fundamental challenge of unstable resistive switching behavior in memristors. Moreover, we aimed to investigate the effects of light illumination in terms of intensity and wavelength on the performance of the fabricated memristor. The parameters such as …

Perovskite Thin Films Annealed In Supercritical Fluids For Efficient Solar Cells, Gilbert Annohene

Theses and Dissertations

In the field of photovoltaics, scientists and researchers are working fervently to produce a combination of efficient, stable, low cost and scalable devices. Methylammonium lead trihalide perovskite has attracted intense interest due to its high photovoltaic performance, low cost, and ease of manufacture. Their high absorption coefficient, tunable bandgap, low-temperature processing, and abundant elemental constituent provide innumerable advantages over other thin film absorber materials. Since the perovskite film is the most important in the device, morphology, crystallization, compositional and interface engineering have been explored to boost its performance and stability. High temperatures necessary for crystallization of organic-inorganic hybrid perovskite films …

Fabrication Of Nanoscale Columnar Diodes By Glancing Angle Deposition, Jacob D. Weightman

Macalester Journal of Physics and Astronomy

Glancing angle deposition (GLAD) is a process in which thin films are deposited onto a substrate with obliquely incident vapor together with precisely controlled azimuthal substrate rotation. Ballistic shadowing effects due to the oblique incidence produce nanoscale structures, and a variety of feature shapes, including tilted columns, helices, and vertical columns can be achieved by varying the azimuthal rotation during the deposition process. Due to this control of morphology and the compatibility of the process with a wide variety of materials, GLAD films have found applications in a variety of fields including sensing, photonics, photovoltaics, and catalysis, where they are …

Nanostructured Metal Thin Films As Components Of Composite Membranes For Separations And Catalysis, Michael J. Detisch

Theses and Dissertations--Chemical and Materials Engineering

Novel metallic thin film composite membranes are synthesized and evaluated in this work for improved separations and catalysis capabilities. Advances in technology that allow for improved membrane performance in solvent separations are desirable for low molecular weight organic separation applications such as those in pharmaceutical industries. Additionally, the introduction of catalytic materials into membrane systems allow for optimization of complex processes in a single step. By adding a nanostructured metallic thin film to its surface, a polymer membrane may be modified to exhibit these improved properties. Using magnetron sputtering, thin metal films may be deposited on commercially available membranes to …

Gamma-Ray Radiation Effects In Graphene-Based Transistors With H-Bn Nanometer Film Substrates, E. J. Cazalas, Michael R. Hogsed, S. R. Vangala, Michael R. Snure, John W. Mcclory

Faculty Publications

Radiation effects on graphene field effect transistors (GFETs) with hexagonal boron nitride (h-BN) thin film substrates are investigated using 60Co gamma-ray radiation. This study examines the radiation response using many samples with varying h-BN film thicknesses (1.6 and 20 nm thickness) and graphene channel lengths (5 and 10 μm). These samples were exposed to a total ionizing dose of approximately 1 Mrad(Si). I-V measurements were taken at fixed time intervals between irradiations and postirradiation. Dirac point voltage and current are extracted from the I-V measurements, as well as mobility, Dirac voltage hysteresis, and the total number of GFETs that remain …

Novel Methods For The Crystallization Of Thin Film Silicon, Shane Mcmahon

Legacy Theses & Dissertations (2009 - 2024)

Underpinning much of the technological innovation over the past few decades in the fields of sensors, lighting, displays, and energy conversion has been thin-film electronics. While many of the surfaces in our environment have curvature, silicon wafers do not. Flexible electronics attempt to overcome this fundamental limitation in form factor. Flexible thin-film transistors (TFTs) can be fabricated over large areas to provide switching and driving elements for displays and other devices. While printable organic semiconductors have made significant advances over the past few years, they cannot match the performance capability, electrical quality, temperature compatibility, or stability of silicon. For this …

Ultra-Thin Boron Nitride Films By Pulsed Laser Deposition: Plasma Diagnostics, Synthesis, And Device Transport, Nicholas Robert Glavin

Open Access Dissertations

This work describes, for the first time, a pulsed laser deposition (PLD) technique for growth of large area, stoichiometric ultra-thin hexagonal and amorphous boron nitride for next generation 2D material electronics. The growth of boron nitride, in this case, is driven by the high kinetic energies and chemical reactivities of the condensing species formed from physical vapor deposition (PVD) processes, which can facilitate growth over large areas and at reduced substrate temperatures. The use of optical emission spectroscopy during plasma growth provides insight into chemistry, kinetic energies, time of flight data, and spatial distributions within a PVD plasma plume ablated …

Development Of Low-Temperature Atomic Layer Deposition Of Ultra-Thin Ruco Direct Plate Liners For Flexible Electronics Applications, Dillon Alexander Gregory

Legacy Theses & Dissertations (2009 - 2024)

Low temperature plasma-assisted atomic layer deposition-grown metal nanocomposite layers based on mixtures of ruthenium and cobalt have been investigated as potential copper adhesion/barrier layers in flexible electronics applications. The success of adapting this process to flexible electronics depends on the candidate barriers meeting several necessary properties including sufficient electrical conductivity, compatibility with Cu electroplating, and ability to prevent Cu diffusion into the substrate. Preliminary testing has shown that atomic layer deposition (ALD) can be used as a technique for depositing alloyed metallic barrier layers at the lower thermal constraints dictated by the use of polymer substrates and still produce continuous …

Engineering The Ground State Of Complex Oxides, Derek Joseph Meyers

Graduate Theses and Dissertations

Transition metal oxides featuring strong electron-electron interactions have been at the forefront of condensed matter physics research in the past few decades due to the myriad of novel and exciting phases derived from their competing interactions. Beyond their numerous intriguing properties displayed in the bulk they have also shown to be quite susceptible to externally applied perturbation in various forms. The dominant theme of this work is the exploration of three emerging methods for engineering the ground states of these materials to access both their applicability and their deficiencies.

The first of the three methods involves a relatively new set …

Initiated Chemical Vapor Deposition (Icvd) Polymer Thin Films : Structure-Property Effects On Thermal Degradation And Adhesion, Vijay Jain Bharamaiah Jeevendrakumar

Legacy Theses & Dissertations (2009 - 2024)

Opportunities and challenges for chemical vapor deposition (CVD) of polymer thin films stems from their applications in electronics, sensors, and adhesives with demands for control over film composition, conformity and stability. Initiated chemical vapor deposition (iCVD) is a subset of the CVD technique that conjoins bulk free-radical polymerization chemistry with gas-phase processing. The novelty of iCVD technique stems from the use of an initiator that can be activated at low energies (150 – 300 °C) to react with surface adsorbed monomer to form a polymer film. This reduces risk for potential unwarranted side-reactions.

The Impact Of Seed Layer Structure On The Recrystallization Of Ecd Cu And Its Alloys, Brendan B. O'Brien

Legacy Theses & Dissertations (2009 - 2024)

Despite the significant improvements originally offered by the use of Cu over Al as the interconnect material for semiconductor devices, the continued down-scaling of interconnects has presented significant challenges for semiconductor engineers. As the metal line widths shrink, both the conductivity and reliability of lines decrease due to a stubbornly fine-grained microstructure in narrow lines.

Maximum Screening Fields Of Superconducting Multilayer Structures, Alex Gurevich

Physics Faculty Publications

It is shown that a multilayer comprised of alternating thin superconducting and insulating layers on a thick substrate can fully screen the applied magnetic field exceeding the superheating fields H_sof both the superconducting layers and the substrate, the maximum Meissner field is achieved at an optimum multilayer thickness. For instance, a dirty layer of thickness ~0.1μm at the Nb surface could increase H_s similar or equal to 240 mT of a clean Nb up to H_s similar or equal to 290 mT. Optimized multilayers of Nb₃Sn, NbN, some of the iron pnictides, or alloyed …

The Ph Sensing Properties Of Rf Sputtered Ruo2 Thin-Film Prepared Using Different Ar/O2 Flow Ratio, Ali Sardarinejad, Devendra Kumar Maurya, Kamal Alameh

Research outputs 2014 to 2021

The influence of the Ar/O₂ gas ratio during radio frequency (RF) sputtering of the RuO₂ sensing electrode on the pH sensing performance is investigated. The developed pH sensor consists in an RF sputtered ruthenium oxide thin-film sensing electrode, in conjunction with an electroplated Ag/AgCl reference electrode. The performance and characterization of the developed pH sensors in terms of sensitivity, response time, stability, reversibility, and hysteresis are investigated. Experimental results show that the pH sensor exhibits super-Nernstian slopes in the range of 64.33-73.83 mV/pH for Ar/O₂ gas ratio between 10/0-7/3. In particular, the best pH sensing performance, in …

The Development Of 6.7% Efficient Copper Zinc Indium Selenide Devices From Copper Zinc Indium Sulfide Nanocrystal Inks, Brian Kemp Graeser

Open Access Theses

As solar cell absorber materials, alloys of CuIn(S,Se)2 and Zn(S,Se) provide an opportunity to reduce the usage of indium along with the ability to tune the band gap. Here we report successful synthesis of alloyed (CuInS2 )0.5(ZnS)0.5 nanocrystals by a method that solely uses oleylamine as the liquid medium for synthesis. The reactive sintering of a thin film of these nanocrystals via selenization at 500 °C results in a uniform composition alloy (CuIn(S,Se)2 )0.5 (Zn(S,Se)) 0.5 layer with micron size grains. Due to the large amount of zinc in the film, the sintered grains exhibit the zinc blende structure instead …

Metrology Of Epitaxial Thin Films And Periodic Nanostructures Using High Resolution X-Ray Diffraction Techniques, Manasa Medikonda

Legacy Theses & Dissertations (2009 - 2024)

The continued scaling of device size to achieve higher performance and/or lower power operation at lower cost is driving research and development into new, 3D transistor structures such as the FinFET. This research and development effort is highlighting the need for new, advanced measurement capability that is highly accurate, reliable, rapid, and nondestructive. Periodic arrays of fin structures enable process monitoring at each level of fabrication and the maintenance of overall device yield. High resolution x-ray diffraction (HR XRD) has been shown to provide unique capability of characterizing blanket thin films and structural parameters of periodic arrays of fins fabricated …

Plasmonic-Based High Temperature Chemical Sensing Using Gold Nanoparticles Embedded In Metal Oxide Thin Films, Nicholas Joy

Legacy Theses & Dissertations (2009 - 2024)

Thin metal oxide films embedded with Au nanoparticles (AuNPs) have been investigated as high temperature localized surface plasmon resonance (LSPR) based sensing materials to monitor H₂, CO, and NO₂ at a temperature of 500°C. Applications for this technology include turbine engines as well as other combustion environments where it is important to monitor emission gases for both regulatory purposes as well as combustion control. These high temperature applications, which may be oxidizing or reducing in nature, present challenges to sensor reliability and selectivity, and have therefore necessitated the development of novel sensing devices. While there has been …

Plasma-Enhanced Atomic Layer Deposition Of Ruthenium-Titanium Nitride Mixed-Phase Layers For Direct-Plate Liner And Copper Diffusion Barrier Applications, Adam James Gildea

Legacy Theses & Dissertations (2009 - 2024)

Current interconnect networks in semiconductor processing utilize a sputtered TaN diffusion barrier, Ta liner, and Cu seed to improve the adhesion, microstructure, and electromigration resistance of electrochemically deposited copper that fills interconnect wires and vias. However, as wire/via widths shrink due to device scaling, it becomes increasingly difficult to have the volume of a wire/via be occupied with ECD Cu which increases line resistance and increases the delay in signal propagation in IC chips. A single layer that could serve the purpose of a Cu diffusion barrier and ECD Cu adhesion promoter could allow ECD Cu to occupy a larger …

Pulse Sharpening Effects Of Thin Film Ferroelectric Transmission Lines, Robert J. Sleezer

Graduate Theses and Dissertations

Advances in material science have resulted in the development of electrically nonlinear high dielectric thin film ferroelectrics, which have led to new opportunities for the creation of novel devices. This dissertation investigated one such device: a low voltage nonlinear transmission line (NLTL). A finite element simulation of ferroelectric transmission lines showed that NLTLs are capable of creating shockwaves. Additionally, if the losses are kept sufficiently low, it was shown that voltage gain should be possible. Furthermore, a method of accounting for material dispersion was developed. Results from simulations including material dispersion showed that temporal solitons might be possible from a …

Nanowire Giant Magnetoresistance Thin Films For Magnetic Sensors, Bryan Cox

Doctoral Dissertations

This dissertation details a novel method to fabricate magnetic sensors using nanowire giant magnetoresistance (GMR) thin films. In 1988, Albert Fert and Peter Grünberg both independently discovered a new physical phenomenon called GMR. GMR is a quantum mechanical effect found in thin film materials that are composed of alternating nanoscale ferromagnetic and non-magnetic conductive layers. When a GMR material is in the presence of a magnetic field, a change in electrical resistance is observed. The GMR effect has been utilized to produce magnetic sensors that have been used in a variety of applications, such as computer hard drive read heads, …

Ultrafast Electron Diffraction Study Of The Dynamics Of Antimony Thin Films And Nanoparticles, Mahmoud Abdel-Fattah

Electrical & Computer Engineering Theses & Dissertations

The ultrafast fast phenomena that take place following the application of a 120 fs laser pulse on 20 nm antimony thin films and 40 nm nanoparticles were studied using time-resolved electron diffraction. Samples are prepared by thermal evaporation, at small thickness (< 10 nm) antimony nanoparticles form while at larger thicknesses we get continuous thin films.

The samples are annealed and studied by static heating to determine their Debye temperatures, which were considerably less than the standard value. The thermal expansion under static heating also yielded the expansion coefficient of the sample material. Nanoparticle samples gave a very accurate thermal expansion coefficient (11 × 10^-6 K^-1).

Ultrafast time resolved electron diffraction …

Extreme Ultraviolet Photoresists : Film Quantum Yields And Ler Of Thin Film Resists, Craig D. Higgins

Legacy Theses & Dissertations (2009 - 2024)

Extreme ultraviolet (EUV) is the leading candidate for a commercially viable solution for next generation lithography. The development of EUV chemically amplified photoresists and processes are critical to the future lithographic requirements of the microelectronics industry. To meet the necessary requirements for both integrated circuit (IC) specifications and cost, the resolution, line-edge roughness (LER) and sensitivity all need to be reduced. Unfortunately, a fundamental trade-off has been observed between these three crucial elements. We have predicted that the best way to obtain the required resolution, line-edge roughness and sensitivity (RLS) is to create more acid molecules per photon absorbed. This …

Development Of High Band Gap Absorber And Buffer Materials For Thin Film Solar Cell Applications, Daniel Dwyer

Legacy Theses & Dissertations (2009 - 2024)

CuInGaSe₂ (CIGS) device efficiencies are the highest of the thin film absorber materials (vs. CdTe, α-Si, CuInSe₂). However, the band gap of the highest efficiency CIGS cells deviates from the expected ideal value predicted by models. Widening the band gap to the theoretically ideal value is one way to increase cell efficiencies. Widening the band gap can be accomplished in two ways; by finding a solution to the Ga-related defects which limit the open circuit voltage at high Ga ratios, or by utilizing different elemental combinations to form an alternative high band gap photoactive Cu-chalcopyrite (which includes …

Nanocomposite Thin Films Of Au Nanoparticles Embedded In Yttria-Stabilized Zirconia For Plasmonic-Based Harsh Environment Gas Detection, Phillip Henry Rogers

Legacy Theses & Dissertations (2009 - 2024)

Increased health concerns due to the emission of gases linked to the production of tropospheric ozone by petroleum based fuel burning engines has resulted in the codification of more stringent emissions regulations domestically. Emissions regulations on commercial jetliners are one of the areas to be met with stricter standards. Currently there is not a sensing technology that can detect the emissions gases in the exhaust stream of a jet turbine engine with lower detection limits that meet these standards.

Fabrication Of Robust Superconducting Granular Aluminium/Palladium Bilayer Microbolometers With Sub-Nanosecond Response, Thomas E. Wilson

Physics Faculty Research

We provide a convenient recipe for fabricating reliable superconducting microbolometers as acoustic phonon detectors with sub-nanosecond response, using imagereversal optical lithography and dc-magnetron sputtering, and our recipe requires no chemical or plasma etching. Our approach solves the traditional problem for granular aluminium bolometers of unreliable (i.e., non-Ohmic) electrical contacts by sequentially sputtering the granular aluminium film and then a palladium capping layer. We use dc calibration data, the method of Danilchenko et al. [1], and direct nanosecond-pulsed photoexcitation to obtain the microbolometer’s characteristic current, thermal conductance, characteristic relaxation time, and heat capacity. We also demonstrate the use of the deconvolution …