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Articles 1 - 17 of 17
Full-Text Articles in Physics
Development And Implementation Of A Pressure-Temperature Control System For The Physical Vapor Deposition Of Copper And Niobium From A Molybdenum Filament In The Development Of Superconducting 3d Printed Rf Cavity Particle Accelerators, Chandler J. Fleuette
Student Research Projects
This report covers the development of the pressure-temperature control system used in the production of small superconducting RF cavities for particle accelerators. To test the validity of the created program, a model for the process was created and tested. The model was used to fine tune the control system before integrating it into the lab. The end goal of the control system is to measure the pressure inside of a deposition vacuum chamber, convert that pressure to a temperature, and use that temperature in tandem with a PID controller to control the current passing though a molybdenum filament which is …
Development And Implementation Of A Pressure-Temperature Control System For The Physical Vapor Deposition Of Copper And Niobium From A Molybdenum Filament In The Development Of Superconducting 3d Printed Rf Cavity Particle Accelerators, Chandler J. Fleuette
Honors Theses and Capstones
This report covers the development of the pressure-temperature control system used in the production of small superconducting RF cavities for particle accelerators. To test the validity of the created program, a model for the process was created and tested. The model was used to fine tune the control system before integrating it into the lab. The end goal of the control system is to measure the pressure inside of a deposition vacuum chamber, convert that pressure to a temperature, and use that temperature in tandem with a PID controller to control the current passing though a molybdenum filament which is …
Development And Characterization Of Nb₃N/Al₂0₃ Superconducting Multilayers For Particle Accelerators, Chris Sundahl, Junki Makita, Paul B. Welander, Yi-Feng Su, Fumitake Kametani, Lin Xie, Huimin Zhang, Lian Li, Alex Gurevich, Chang-Beom Eom
Development And Characterization Of Nb₃N/Al₂0₃ Superconducting Multilayers For Particle Accelerators, Chris Sundahl, Junki Makita, Paul B. Welander, Yi-Feng Su, Fumitake Kametani, Lin Xie, Huimin Zhang, Lian Li, Alex Gurevich, Chang-Beom Eom
Physics Faculty Publications
Superconducting radio-frequency (SRF) resonator cavities provide extremely high quality factors > 1010 at 1-2 GHz and 2 K in large linear accelerators of high-energy particles. The maximum accelerating field of SRF cavities is limited by penetration of vortices into the superconductor. Present state-of-the-art Nb cavities can withstand up to 50 MV/m accelerating gradients and magnetic fields of 200-240 mT which destroy the low-dissipative Meissner state. Achieving higher accelerating gradients requires superconductors with higher thermodynamic critical fields, of which Nb3Sn has emerged as a leading material for the next generation accelerators. To overcome the problem of low vortex penetration …
Growth And Characterization Of 2d Layered Materials, Algene Fryer Ii
Growth And Characterization Of 2d Layered Materials, Algene Fryer Ii
USF Tampa Graduate Theses and Dissertations
2D layered materials are becoming an important area of research due to their exceptional electrical and optical properties. Specifically, 2D layered monochalcogenides are known for their high carrier motilities, whereas layered metal halides have been shown to have noteworthy photoresponsivity. Despite the assortment of 2D layered materials, the search for reliable and scalable synthesis methods is still a challenge in this family of materials. Often a certain growth technique will compromise a desirable trait needed for further fabrication, such as the quality of the crystal or its coverage on a substrate. In this study, two growth techniques that incorporate changeable …
Modeling And Simulation Of Driven Nanopatterning Of Bulk-Material And Thin-Film Surfaces, Ashish Kumar
Modeling And Simulation Of Driven Nanopatterning Of Bulk-Material And Thin-Film Surfaces, Ashish Kumar
Doctoral Dissertations
Material nanostructures such as nanowires, quantum dots, and nanorings have a wide variety of applications in electronic and photonic devices among numerous others. Assembling uniformly arranged and consistently sized nanostructure patterns on solid material surfaces is a major challenge for nanotechnology. This dissertation focuses on developing predictive models capable of simulation and analysis of such nanopattern formation on bulk material and strained thin film surfaces. Single-layer atomic clusters (islands) of sizes larger than a critical size on crystalline conducting substrates undergo morphological instabilities when driven by an externally applied electric field or thermal gradient. We have conducted a systematic and …
Physical Electronic Properties Of Self-Assembled 2d And 3d Surface Mounted Metal-Organic Frameworks, Radwan Elzein
Physical Electronic Properties Of Self-Assembled 2d And 3d Surface Mounted Metal-Organic Frameworks, Radwan Elzein
USF Tampa Graduate Theses and Dissertations
Metal-organic frameworks stand at the frontiers of molecular electronic research because they combine desirable physical properties of organic and inorganic components. They are crystalline porous solids constructed by inorganic nodes coordinated to organic ligands to form 1D, 2D, or 3D structures. They possess unique characteristics such as ultrahigh surface area crystal lattices up to 10000 m2 g-1, and tunable nanoporous sizes ranging from 0.2 to 50 nm. Their unprecedented structural diversity and flexibility beyond solid state materials can lead to unique properties such as tailorable electronic and ionic conductivity which can serve as interesting platforms for a …
Growth And Characterization Of Znse Thin Films By Rf Magnetron Co-Sputtering, Hallie Miller
Growth And Characterization Of Znse Thin Films By Rf Magnetron Co-Sputtering, Hallie Miller
Honors Projects and Presentations: Undergraduate
Zinc-selenide, ZnSe,is aII-IV semiconductor that is known for its wide band gap of ~2.6 eV. In the growing world of advanced electronics, ZnSe thin films are useful to study in order to widen our understanding of semiconductor physics and to enable us to create and develop higher preforming electronics. In this study, we have grown ZnSe thin films by radio frequency (RF) magnetron sputtering. We are specifically seeking to understand how the ratio of Zinc to Selenium,and the temperature the films are grown at, affects the band gap and crystalline structure. Ten different ratios of Zn to Se were grown, …
Structure And Optical Properties Of Transition Metal Dichalcogenides (Tmds) – Mx2 (M = Mo, W & X = S, Se) Under High Pressure And High Temperature Conditions, Nirup Reddy Bandaru
Structure And Optical Properties Of Transition Metal Dichalcogenides (Tmds) – Mx2 (M = Mo, W & X = S, Se) Under High Pressure And High Temperature Conditions, Nirup Reddy Bandaru
UNLV Theses, Dissertations, Professional Papers, and Capstones
Layered structured materials such as transition metal dichalcogenides (TMDs) have gained immense interest in recent times due to their exceptional structural, electrical and optical properties. Recent studies show semiconducting TMDs such as MX2 (M= Mo, W & X = S, Se) could be used as potential shock absorbing material, which has resulted in extensive studies on structural stability of these materials under the influence of high pressure. Understanding the structural stability of transition metal dichalcogenides (TMDs) such as MoS2, MoSe2, WS2, and WSe2 under high pressure has been very challenging due to contradicting observations and interpretations reported in the …
Molecular Dynamics Study On Defect Reduction Strategies Towards The Fabrication Of High Performance Cd1-Xznxte/Cds Solar Cells, Jose Juan Chavez
Molecular Dynamics Study On Defect Reduction Strategies Towards The Fabrication Of High Performance Cd1-Xznxte/Cds Solar Cells, Jose Juan Chavez
Open Access Theses & Dissertations
Cadmium Telluride is a material widely used in terrestrial thin film photovoltaic applications due to its nearly ideal band gap (~1.5 eV) and high absorption coefficient. Due to its low manufacturing cost, this technology has the potential to become a significant energy resource if higher energy conversion efficiencies are achieved. However, the module efficiencies (~14%) are still far from the theoretical maximum (~30%) for this material in a single junction configuration. The reason behind this low performance is attributed to the high number of defects that are present within the device materials. The physics behind the formation mechanisms of these …
Polariton Evaporation: The Blackbody Radiation Nature Of The Low-Frequency Radiation Emitted By Radiative Polaritons To The Surrounding Space, Yosep Schwab, Harkirat S. Mann, Brian N. Lang, Giovanna Scarel
Polariton Evaporation: The Blackbody Radiation Nature Of The Low-Frequency Radiation Emitted By Radiative Polaritons To The Surrounding Space, Yosep Schwab, Harkirat S. Mann, Brian N. Lang, Giovanna Scarel
Department of Physics and Astronomy - Faculty Scholarship
Upon formation, radiative polaritons in thin oxide films or crystals emit radiation to the surrounding space. This radiation is confined in a small range of the microwave to far-infrared region of the electromagnetic spectrum, independently of the oxide chemistry. This work shows that the low-frequency radiation is blackbody radiation associated with a temperature directly related to the boson character of the radiative polaritons and to their amount. The proximity of this temperature to absolute zero Kelvin explains the confinement of the frequency. This phenomenon is named polariton evaporation.
Growth Of Zno Thin Films On Polar Oxide Surfaces By Atomic Layer Deposition, Kallol Pradhan
Growth Of Zno Thin Films On Polar Oxide Surfaces By Atomic Layer Deposition, Kallol Pradhan
Theses and Dissertations
Polar heterointerfaces of MgO(111) and the II-VI semiconductor ZnO are of technological interest for transparent conducting electrode applications. Growth and structure of thin films on polar surfaces can be different than on non-polar surfaces due to the large surface energy of polar surfaces. We have grown ZnO on unreconstructed MgO(111)-(1x1)-OH terminated and reconstructed MgO(111)-(√3x√3)R30° polar oxide surfaces using atomic layer deposition. A homemade UHV-interfaced viscous-flow atomic layer deposition (ALD) reactor with in-situ quartz crystal monitor was used to grow ZnO thin films on the MgO(111) substrates. Surface morphology studies revealed that the surface roughness increases with ZnO film thickness and …
Nonlinear Effects In Magnetic Garnet Films And Nonreciprocal Optical Bloch Oscillations In Waveguide Arrays, Pradeep Kumar
Nonlinear Effects In Magnetic Garnet Films And Nonreciprocal Optical Bloch Oscillations In Waveguide Arrays, Pradeep Kumar
Dissertations, Master's Theses and Master's Reports - Open
This dissertation presents detailed experimental and theoretical investigations of nonlinear and nonreciprocal effects in magnetic garnet films. The dissertation thus comprises two major sections. The first section concentrates on the study of a new class of nonlinear magneto-optic thin film materials possessing strong higher order magnetic susceptibility for nonlinear optical applications. The focus was on enlarging the nonlinear performance of ferrite garnet films by strain generation and compositional gradients in the sputter-deposition growth of these films. Under this project several bismuth-substituted yttrium iron garnet (Bi,Y) 3 (Fe,Ga)5 O12(acronym as Bi:YIG) films have been sputter-deposited over gadolinium gallium …
Crystal Structure, Phase, And Optical Properties Of Yttrium-Doped Hafnium Oxide Nanocrystalline Thin Films, Alejandro Ortega
Crystal Structure, Phase, And Optical Properties Of Yttrium-Doped Hafnium Oxide Nanocrystalline Thin Films, Alejandro Ortega
Open Access Theses & Dissertations
Yttrium-doped hafnium oxide (YDH) nanocrystalline films were produced by sputter-deposition at various substrate times and temperatures, to produce YDH films in a wide range of thicknesses, dYDH∼25 to 1100 nm. The deposition was made onto optical grade quartz and sapphire substrates. Samples deposited on sapphire were subject to post-deposition annealing (PDA) at various times (3-24 hr) and temperatures (1100 - 1500 °C). The effect of d[special characters omitted]YDH on the crystal structure, surface/interface morphology and optical properties of YDH films was investigated. X-ray diffraction analyses revealed the formation of monoclinic phase for relatively thin films (<150nm). The evolution towards stabilized cubic phase with increasing dYDH [special characters omitted]is observed. The scanning electron microscopy results indicate the dense, columnar structure of YDH films as a function of dYDH. Spectrophotometry analyses indicate that the grown YDH films are transparent and exhibit interference fringes. The band gap was found to be ∼ 5.60 eV for monoclinic YDH films while distinct separation and an increase in band gap to 6.03 eV is evident with increasing dYDH and formation cubic YDH films. The PDA films band gaps were found to be between 5.31 and 5.72 eV, all of which exhibit secondary gaps. A correlation between growth conditions, annealing, phase evolution, and optical properties of the YDH nanocrystalline thin films is established.
Photorefractive Thin Films And Polymers For Use In Organic-Inorganic Hybrid Cells, Steven Harris Buller
Photorefractive Thin Films And Polymers For Use In Organic-Inorganic Hybrid Cells, Steven Harris Buller
Browse all Theses and Dissertations
Two classes of materials were investigated as possible replacements for the bulk photorefractive windows in inorganic-organic hybrid cells: thin films and polymers. Each material was fabricated and subsequently characterized using two different methods due to their different stages of development. The thin films were characterized by X-ray diffraction while the polymers were characterized by two-beam coupling. Thin films of strontium barium niobate and potassium niobate were grown, using pulsed laser deposition, on four different substrates. It was found that it was possible to grow a thin film of potassium niobate in the correct orientation to replace a bulk photorefractive window. …
Dielectric Constant Measurements Using Atomic Force Microscopy System, Hembathanthirige Yasas Dhanapala
Dielectric Constant Measurements Using Atomic Force Microscopy System, Hembathanthirige Yasas Dhanapala
Browse all Theses and Dissertations
A new technique to obtain local dielectric constant of thin films was developed using atomic force microscopy system. This technique, in addition to other characterization methods such as AFM imaging and X-Ray diffraction, was used to study, as an example, dielectric constant of thin films of 0.3BiScO3 - 0.7BaTiO3. The thin films were fabricated by using pulsed laser deposition technique under following temperature of the substrate: 6500C, 7000C and 7500C. At each temperature, two different oxygen pressures were used in deposition chamber: 50 mTorr and 100 mTorr. Our goal was to find optimal growth conditions with the highest dielectric constant …
An Investigation Of Pinning Landscapes With Engineered Defects: Contact-Free Critical Current Density Measurements, John William Sinclair
An Investigation Of Pinning Landscapes With Engineered Defects: Contact-Free Critical Current Density Measurements, John William Sinclair
Doctoral Dissertations
Pinning landscapes in modern second generation coated conductors are excellent candidates for studies of vortex pinning. The ability to produce engineered defects in thin films of high temperature superconductors allows one to investigate representative distinct pinning sites, with the objective of understanding how different pinning centers contribute, compete and evolve under varying conditions of magnetic field strength and orientation, and temperature.New contact-free methods were developed specifically to investigate this system in new ways, especially the dependence of the critical current density Jc on orientation of the magnetic field. A superconducting quantum interference device (SQUID)-based magnetometer was used to determine angular …
The Effects Of Rare Earth Doping On Gallium Nitride Thin Films, Stephen R. Mchale
The Effects Of Rare Earth Doping On Gallium Nitride Thin Films, Stephen R. Mchale
Theses and Dissertations
The thermal neutron capture cross section of the rare earth (RE) metal isotope Gd-157 is the largest of all known natural elements, which distinguishes the material as a logical candidate for neutron detection. To address an incomplete understanding of rare earth doped Gallium Nitride (GaN) materials, investigations of the surface electronic structure and interface properties of GaN thin films doped with rare earths (Yb, Er, Gd) were undertaken. Lattice ion occupation, bonding, rare earth 4f occupation, and gold Schottky barrier formation were examined using synchrotron photoemission spectroscopy. Measured Debye temperatures indicate substitutional occupation of Ga sites by RE ions. The …