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Full-Text Articles in Engineering
Gate-Controlled Quantum Dots In Two-Dimensional Tungsten Diselenide And One-Dimensional Tellurium Nanowires, Shiva Davari Dolatabadi
Gate-Controlled Quantum Dots In Two-Dimensional Tungsten Diselenide And One-Dimensional Tellurium Nanowires, Shiva Davari Dolatabadi
Graduate Theses and Dissertations
This work focuses on the investigation of gate-defined quantum dots in two-dimensional transition metal dichalcogenide tungsten diselenide (WSe2) as a means to unravel mesoscopic physical phenomena such as valley-contrasting physics in WSe2 flakes and its potential application as qubit, as well as realizing gate-controlled quantum dots based on elementaltellurium nanostructures which may unlock the topological nature of the host material carriers such as Weyl states in tellurium nanowires.The fabrication and characterization of gate-defined hole quantum dots in monolayer and bilayer WSe2 are reported. The gate electrodes in the device design are located above and below the WSe2 nanoflakes to accumulate …
Study Of Thick Indium Gallium Nitride Graded Structures For Future Solar Cell Applications, Manal Abdullah Aldawsari
Study Of Thick Indium Gallium Nitride Graded Structures For Future Solar Cell Applications, Manal Abdullah Aldawsari
Graduate Theses and Dissertations
Indium gallium nitride (InxGa1-xN) materials have held great potential for the optoelectronic industry due to their electrical and optical properties. The tunable band gap that can span the solar spectrum was one of the most significant features that attracted researchers’ attention. The band gap can be varied continuously from 0.77 eV for InN to 3.42 eV for GaN, covering the solar spectrum from near infrared to near ultraviolet. Additionally, it has a high absorption coefficient on the order of ∼105 cm−1, a direct band gap, high radiation resistance, thermal stability, and so on. Nevertheless, the epitaxial growth of high quality …
Mitigation Of Electromigration In Metal Interconnects Passivated By Ångstrom-Thin 2d Materials, Yunjo Jeong
Mitigation Of Electromigration In Metal Interconnects Passivated By Ångstrom-Thin 2d Materials, Yunjo Jeong
USF Tampa Graduate Theses and Dissertations
Electromigration in metal interconnects remains one of the most prominent challenges in the state-of-the-art semiconductor industry. A phenomenon defined as the momentum transfer from electrons in an electric current to the metal atoms in a conductor, electromigration creates voids and hillocks that ultimately cause failures in nanoelectronics due to short or open circuits. Additionally, electromigration induces undesirable diffusion of metal atoms into the dielectric material, forcing the need for a barrier material that can mitigate such adverse effects of the phenomenon. However, extremely tight dimensional control of modern transistor designs imposes reduced dimensions of the interconnects in order to accommodate …
Exploring Gated Nanoelectronic Devices Fabricated From 1d And 2d Materials, Prathamesh A. Dhakras
Exploring Gated Nanoelectronic Devices Fabricated From 1d And 2d Materials, Prathamesh A. Dhakras
Legacy Theses & Dissertations (2009 - 2024)
One and two dimensional materials are being extensively researched toward potential application as ultra-thin body channel materials. The difficulty of implementing physical doping methods in these materials has necessitated various alternative doping schemes, the most promising of which is the electrostatic gating technique due to its reconfigurability. This dissertation explores the different fundamental devices that can be fabricated and characterized by taking advantage of the electrostatic gating of individual single-walled carbon nanotubes (SWNTs), dense SWNT networks and exfoliated 2D tungsten diselenide (WSe2) flakes.
Electron Transport In One And Two Dimensional Materials, Samuel William Lagasse
Electron Transport In One And Two Dimensional Materials, Samuel William Lagasse
Legacy Theses & Dissertations (2009 - 2024)
This dissertation presents theoretical and experimental studies in carbon nanotubes (CNTs), graphene, and van der Waals heterostructures. The first half of the dissertation focuses on cutting edge tight-binding-based quantum transport models which are used to study proton irradiation-induced single-event effects in carbon nanotubes [1], total ionizing dose effects in graphene [2], quantum hall effect in graded graphene p-n junctions [3], and ballistic electron focusing in graphene p-n junctions [4]. In each study, tight-binding models are developed, with heavy emphasis on tying to experimental data. Once benchmarked against experiment, properties of each system which are difficult to access in the laboratory, …
Structural, Dielectric, And Ferroelectric Characterization Of Lead-Free Calcium-Cerium Co-Doped Batio3 Ceramics, Juan Alberto Duran
Structural, Dielectric, And Ferroelectric Characterization Of Lead-Free Calcium-Cerium Co-Doped Batio3 Ceramics, Juan Alberto Duran
Open Access Theses & Dissertations
Structure, morphology, and regulation of the dielectric properties via close-composition intervals is demonstrated for variable-cerium, constant-calcium co-doped barium titanate (Ba0.80Ca0.20CeyTi1-yO3; y=0.0-0.25; referred to BCCT). The effect of variable Ce-content on the structure and dielectric properties of BCCT is investigated. X-ray diffraction spectra confirms the studied samples are mainly in BT tetragonal phase with a small secondary phase detected as CaTiO3 in BCCT for y = 0.20 and 0.25. However, the lattice parameter reduction was evident with increasing Ce-content. Composition-driven dielectric constant leap (4,000-5,500) was observed from intrinsic BCT to BCCT for (y = 0.0-0.04). The temperature dependent dielectric constant showed …
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 …
Nanoparticle Generation And Interactions With Surfaces In Vacuum Systems, Yashdeep Khopkar
Nanoparticle Generation And Interactions With Surfaces In Vacuum Systems, Yashdeep Khopkar
Legacy Theses & Dissertations (2009 - 2024)
Extreme ultraviolet lithography (EUVL) is the most likely candidate as the next generation technology beyond immersion lithography to be used in high volume manufacturing in the semiconductor industry. One of the most problematic areas in the development process is the fabrication of mask blanks used in EUVL. As the masks are reflective, there is a chance that any surface aberrations in the form of bumps or pits could be printed on the silicon wafers. There is a strict tolerance to the number density of such defects on the mask that can be used in the final printing process. Bumps on …
Design And Development Of Stress Engineering Techniques For Iii-Nitride Epitaxy On Si, Jeff Leathersich
Design And Development Of Stress Engineering Techniques For Iii-Nitride Epitaxy On Si, Jeff Leathersich
Legacy Theses & Dissertations (2009 - 2024)
III-Nitrides have been a heavily researched material system for decades. Their material properties are favorable for a number of applications, most commonly in the optoelectronic and power device industry. Currently a majority of commercialized devices are fabricated on sapphire and SiC substrates but these are expensive and limit the widespread commercialization of the technology. There is substantial ongoing research geared toward the development of GaN on Si substrates because of the significant cost saving that would be realized through the inexpensive, large wafer and maturity of Si fabrication. Significant challenges with the deposition of GaN on Si have, thus far, …
An Assessment Of Critical Dimension Small Angle X-Ray Scattering Metrology For Advanced Semiconductor Manufacturing, Charles Michael Settens
An Assessment Of Critical Dimension Small Angle X-Ray Scattering Metrology For Advanced Semiconductor Manufacturing, Charles Michael Settens
Legacy Theses & Dissertations (2009 - 2024)
Simultaneous migration of planar transistors to FinFET architectures, the introduction of a plurality of materials to ensure suitable electrical characteristics, and the establishment of reliable multiple patterning lithography schemes to pattern sub-10 nm feature sizes imposes formidable challenges to current in-line dimensional metrologies. Because the shape of a FinFET channel cross-section immediately influences the electrical characteristics, the evaluation of 3D device structures requires measurement of parameters beyond traditional critical dimension (CD), including their sidewall angles, top corner rounding and footing, roughness, recesses and undercuts at single nanometer dimensions; thus, metrologies require sub-nm and approaching atomic level measurement uncertainty.
Fundamental Studies Of Supported Graphene Interfaces : Defect Density Of States In Graphene Field Effect Transistors (Fets) And Ideal Graphene - Silicon Schottky Diodes, Dhiraj Sinha
Legacy Theses & Dissertations (2009 - 2024)
The physics of transport in atomically thin 2D materials is an active area of research, important for understanding fundamental properties of reduced dimensional materials and for applications. New phenomena based on graphene may include properties of topologically protected insulators. Applications of these materials are envisioned in electronics, optoelectronics and spintronics.
Towards A Fundamental Understanding Of Inhomogeneous Interfaces Utilizing Ballistic Electron Emission Microscopy, Robert John Balsano
Towards A Fundamental Understanding Of Inhomogeneous Interfaces Utilizing Ballistic Electron Emission Microscopy, Robert John Balsano
Legacy Theses & Dissertations (2009 - 2024)
A fundamental understanding of charge transport across metal/semiconductor interfaces is of great technological and scientific importance. Metal/semiconductor, or Schottky barrier devices are widely utilized in sensing applications and power electronics. Additionally, Schottky barriers appear in resistive memory technology and current transistor technology. Although Schottky interfaces are ubiquitous, the effects of spatially variant interfaces on the measured Schottky barrier height (SBH) are not entirely understood. For these reasons it is necessary to explore the spatial variation at Schottky interfaces at the nanoscale. Ballistic electron emission microscopy (BEEM) is a three terminal scanning tunneling microscopy (STM) technique used to measure hot carrier …
Fluorescence Characterization Of Quantum Dots For Use As Biomarkers, Logan M. Grimes
Fluorescence Characterization Of Quantum Dots For Use As Biomarkers, Logan M. Grimes
Materials Engineering
Fluorescence profiles of quantum dots (QDs) were characterized to select the ideal QDs for encapsulation in phospholipids for use as biomarkers to selectively adhere to cancer cells. QDs were synthesized and extracted 0, 30, 60, and 90 seconds after precursor compounds were mixed. These extractions were isolated by extraction time. Portions from each vial were coated in a zinc sulfide shelling procedure, leaving at least half of the QD solution unshelled. These samples were characterized over four days to monitor fluctuations in fluorescence. This was done utilizing an Ocean Optics spectrometer in conjunction with Spectra Suite software. The central wavelength, …
Mueller Based Scatterometry And Optical Characterization Of Semiconductor Materials, Gangadhara Raja Muthinti
Mueller Based Scatterometry And Optical Characterization Of Semiconductor Materials, Gangadhara Raja Muthinti
Legacy Theses & Dissertations (2009 - 2024)
Scatterometry is one of the most useful metrology methods for the characterization and control of critical dimensions (CD) and the detailed topography of periodic structures found in microelectronics fabrication processes. Spectroscopic ellipsometry (SE) and normal incidence reflectometry (NI) based scatterometry are the most widely used optical methodologies for metrology of these structures. Evolution of better optical hardware and faster computing capabilities led to the development of Mueller Matrix (MM) based Scatterometry (MMS). Dimensional metrology using full Mueller Matrix (16 element) scatterometry in the wavelength range of 245nm-1000nm was discussed in this work. Unlike SE and NI, MM data provides complete …
Understanding Defect Interactions In Si Ultra-Shallow P-N Junctions Formed By Very Low Energy Boron Implantation, Lakshmanan H. Vanamurthy
Understanding Defect Interactions In Si Ultra-Shallow P-N Junctions Formed By Very Low Energy Boron Implantation, Lakshmanan H. Vanamurthy
Legacy Theses & Dissertations (2009 - 2024)
One of the biggest challenges in the scaling of CMOS devices is the formation of a highly activated, abrupt, defect free Source drain extension (SDE) region. This is especially difficult with p-FET's because of the (1) Boron diffusion co-efficient enhancement from Transient enhanced diffusion (TED) and (2) low solid solubility of
Modified Statistical Dynamical Diffraction Theory : A Novel Metrological Analysis Method For Partially Relaxed And Defective C Doped Si And Sige Heterostructures, Paul Kenneth Shreeman
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 …
Synthesis And Characterization Of Cdse-Zns Core-Shell Quantum Dots For Increased Quantum Yield, Joshua James Angell
Synthesis And Characterization Of Cdse-Zns Core-Shell Quantum Dots For Increased Quantum Yield, Joshua James Angell
Master's Theses
Quantum dots are semiconductor nanocrystals that have tunable emission through changes in their size. Producing bright, efficient quantum dots with stable fluorescence is important for using them in applications in lighting, photovoltaics, and biological imaging. This study aimed to optimize the process for coating CdSe quantum dots (which are colloidally suspended in octadecene) with a ZnS shell through the pyrolysis of organometallic precursors to increase their fluorescence and stability. This process was optimized by determining the ZnS shell thickness between 0.53 and 5.47 monolayers and the Zn:S ratio in the precursor solution between 0.23:1 and 1.6:1 that maximized the relative …
Cost-Effective Imprint Template Fabrication For Step And Flash Imprint Lithography, Adam Marc Munder
Cost-Effective Imprint Template Fabrication For Step And Flash Imprint Lithography, Adam Marc Munder
Legacy Theses & Dissertations (2009 - 2024)
The College of Nanoscale Science and Engineering (CNSE) is studying imprint template fabrication with the 100kV Vistec VB300 Gaussian E-Beam writer. The major goal is to develop and advance imprint template fabrication technology using low cost quartz wafers for proof-of-concept demonstrations.
Optimization And Development Of Silicon-Based Semiconductor Devices Using Tcad, Changwoo Lee
Optimization And Development Of Silicon-Based Semiconductor Devices Using Tcad, Changwoo Lee
Legacy Theses & Dissertations (2009 - 2024)
Computer simulation of the electrical and optical properties of semiconductor devices has been became as an essential tool for developing new device as well as for improving existing device. This presentation describes applications of physical device simulation: (1) design optimization of power MOSFET, which is single crystalline based silicon semiconductor device, for cryogenic temperature application and (2) two-dimensional device simulation of amorphous silicon based solar cell to develop novel photovoltaic device with high efficiency.