UNT Theses and Dissertations - 10 Matching Results

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Investigation of Room Temperature Soft Ferromagnetism in Indium Phosphide Substrate Synthesized via Low Energy Nickel Ion Implantation

Description: In this work, we have utilized an ion beam process known as gettering to migrate implanted Ni ions much deeper into the bulk substrate than their initial projected end of the range. The projected mean depth is known as Rp. The gettering effect is the most crucial part of the fabrication and we have found that for an H fluence of 3x 1016 cm-2 there is a threshold fluence of approximately 7.5 x 1015 cm-2 that cannot be surpassed if the gettering process is to be completed along with the substrat… more
Date: May 2021
Creator: Jones, Daniel C.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Modeling, Characterization, and Magnetic Behavior of Transition Metal Nanosystems Synthesized in Silicon Using Low Energy Ion Implantation

Description: Magnetic nano-clusters in silicon involving iron and cobalt were synthesized using low energy (50 keV) ion implantation technique and post-implantation thermal annealing. Before the irradiation, multiple ion-solid interaction simulations were carried out to estimate optimal ion energy and fluence for each experiment. For high-fluence low-energy irradiation of heavy ions in a relatively lighter substrate, modeling the ion irradiation process using dynamic code SDTrimSP showed better agreement w… more
Date: May 2021
Creator: Singh, Satyabrata
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Deep Minima and Vortices for Positronium Formation in Positron-Hydrogen and Positron-Helium Collisions

Description: This dissertation work is a study of positronium formation for positron-hydrogen and positron-helium collisions in the Ore gap (the energy region between the threshold for ground-state positronium formation and the first excitation level of the target atom) using variational K-matrices. We have fitted the K-matrices using multichannel effective range theories and using polynomials. Using the variational K-matrices and their fits, we have located zeros in the positronium-formation scattering amp… more
Date: May 2021
Creator: Alrowaily, Albandari Wanes
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

The Electrochemical Etching Process of a Tungsten Wire

Description: This study produced and analyzed shaped tungsten wire tips formed through electrochemical etching. Specifically, the cone length and the radius of curvature of the tip were analyzed. Having the tips move dynamically through an electrolytic solution, such as potassium hydroxide, and tuning the initial starting depth of the tungsten wire along with the dynamic speed of the tungsten wire as it passed throughout the solution allowed various types of tip profiles to be produced. The tip's radius of … more
Date: August 2021
Creator: Richardson, Aaron Michael
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Classical Simulations of the Drift of Magnetobound States of Positronium

Description: The production and control of antihydrogen at very low temperatures provided a key tool to test the validity for the antimaterial of the fundamental principles of the interactions of nature such as the weak principle of equivalence (WEP), and CPT symmetry (Charge, Parity, and Time reversal). The work presented in this dissertation studies the collisions of electrons and positrons in strong magnetic fields that generate magnetobound positronium (positron-electron system temporarily bound due to … more
Date: August 2021
Creator: Aguirre Farro, Franz
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

A Study of Anomalous Conduction in n-Type Amorphous Silicon and Correlations in Conductivity and Noise in Gold Nanoparticle-Ligand Arrays

Description: This work explores two very different structural systems: n-type hydrogenated amorphous silicon (a-Si:H) and gold nanoparticles (AuNPs) suspended in a matrix of organic ligands. For a-Si:H, examination of the gas-phase concentration of dopant (1-6% PH3/SiH4) and argon diluent effects includes the temperature dependent conductivity, low-frequency electronic noise, and Raman spectroscopy to examine structure. It is found that a-Si:H samples grown with high dopant concentration or with argon dilut… more
Date: August 2021
Creator: Western, Brianna J
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Low-Energy Electron Irradiation of 2D Graphene and Stability Investigations of 2D MoS2

Description: In this work, we demonstrate the mechanism for etching exfoliated graphene on SiO2 and other technological important substrates (Si, SiC and ITO), using low-energy electron sources. Our mechanism is based on helium ion sputtering and vacancy formation. Helium ions instead of incident electrons cause the defects that oxygen reacts with and etches graphene. We found that etching does not occur on low-resistivity Si and ITO. Etching occurs on higher resistivity Si and SiC, although much less than … more
Date: August 2021
Creator: Femi Oyetoro, John Dideoluwa
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Information and Self-Organization in Complex Networks

Description: Networks that self-organize in response to information are one of the most central studies in complex systems theory. A new time series analysis tool for studying self-organizing systems is developed and demonstrated. This method is applied to interacting complex swarms to explore the connection between information transport and group size, providing evidence for Dunbar's numbers having a foundation in network dynamics. A complex network model of information spread is developed. This network in… more
Date: December 2021
Creator: Culbreth, Garland
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Computational Techniques for Accelerated Materials Discovery

Description: Increasing ubiquity of computational resources has enabled simulation of complex electronic systems and modern materials. The PAOFLOW software package is a tool designed to construct and analyze tight binding Hamiltonians from the solutions of DFT calculations. PAOFLOW leverages localized basis sets to greatly reduce computational costs of post-processing QE simulation results, enabling efficient determination of properties such as electronic density, band structures in the presence of electric… more
Date: December 2021
Creator: Cerasoli, Franklin
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Towards Increased Precision of the 4He:23P1→23P2 Transition Measurement Using Laser Spectroscopy

Description: Significant sub-systems were created and others enhanced providing a platform for an order of magnitude precision increase of the small 4He interval - 23P1→23P2 laser spectroscopy measurement, as well as other helium transitions. These measurements serve as tests of helium theory and quantum electro-dynamics in general. Many improvements to the original experiment are discussed and characterized. In particular, counting speed increased 10x, the signal level was doubled, a novel Doppler shift mi… more
Date: December 2021
Creator: Cameron, Garnet
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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