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Electronic Transport Investigation Of Chemically Derived Reduced Graphene Oxide Sheets, Daeha Joung

Electronic Theses and Dissertations

Reduced graphene oxide (RGO) sheet, a chemically functionalized atomically thin carbon sheet, provides a convenient pathway for producing large quantities of graphene via solution processing. The easy processibility of RGO sheet and its composites offer interesting electronic, chemical and mechanical properties that are currently being explored for advanced electronics and energy based materials. However, a clear understanding of electron transport properties of RGO sheet is lacking which is of great significance for determining its potential application. In this dissertation, I demonstrate fabrication of high-yield solution based graphene field effects transistor (FET) using AC dielectrophoresis (DEP) and investigate the detailed electronic …

The Influence Of Copper Substrate Orientation On Graphene Growth, Zachary Robert Robinson

Legacy Theses & Dissertations (2009 - 2024)

This dissertation is focused on determining the influence of the copper substrate on graphene grown by \ac{CVD}. Graphene, which can be grown in single atomic layers on copper substrates, has potential applications in future electronic devices. One of the key issues for the use of graphene grown by chemical vapor deposition for device applications is the influence of defects on the transport properties of the graphene. For instance, growth on metal foil substrates results in multi-domain graphene growth because the foil substrates themselves have a variety of different surface terminations. Therefore, they don't serve as a very good template for …

Electronic And Structural Properties Of Silicene And Graphene Layered Structures, Patrick B. Benasutti

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Graphene is a two-dimensional nanomaterial with useful and novel properties, but it is a material that does not integrate well with the current silicon microchip infrastructure. Silicene could solve this problem, as it is made of silicon yet retains the novel properties that make graphene desirable. This thesis will outline density functional calculations of a newly proposed structure involving the combination of these two materials. The structure includes silicene layered on graphene in such a manner that it composes a superlattice. It will be examined using the ab-initio density functional theory software Quantum Espresso.

This superlattice structure is proposed to …

Graphene Casimir Interactions And Some Possible Applications, Anh Duc Phan

USF Tampa Graduate Theses and Dissertations

Scientific development requires profound understandings of micromechanical and nanomechanical systems (MEMS/NEMS) due to their applications not only in the technological world, but also for scientific understanding. At the micro- or nano-scale, when two objects are brought close together, the existence of stiction or adhesion is inevitable and plays an important role in the behavior operation of these systems. Such effects are due to surface dispersion forces, such as the van der Waals or Casimir interactions. The scientific understanding of these forces is particularly important for low-dimensional materials. In addition, the discovery of materials, such as graphitic systems has provided opportunities …

Development Of Interatomic Potentials For Large Scale Molecular Dynamics Simulations Of Carbon Materials Under Extreme Conditions, Romain Perriot

USF Tampa Graduate Theses and Dissertations

The goal of this PhD research project is to devise a robust interatomic potential for large scale molecular dynamics simulations of carbon materials under extreme conditions. This screened-environment dependent reactive empirical bond order potential (SED-REBO) is specifically designed to describe carbon materials under extreme compressive or tensile stresses. Based on the original REBO potential by Brenner and co workers, SED-REBO includes reparametrized pairwise interaction terms and a new screening term, which serves the role of a variable cutoff. The SED-REBO potential overcomes the deficiencies found with the most commonly used interatomic potentials for carbon: the appearance of artificial forces due …

Transport And Optical Properties Of Quantized Low-Dimensional Systems, Xiaoguang Li

Doctoral Dissertations

In this thesis, we present a systematic investigation of the static and dynamic response properties of low-dimensional systems, using a variety of theoretical techniques ranging from time dependent density functional theory to the recursive Green's function method.

As typical low-dimensional systems, metal nanostructures can strongly interact with an electric field to support surface plasmons, making their optical properties extremely attractive in both fundamental and applied aspects. We have investigated the energy broadening of surface plasmons in metal structures of reduced dimensionality, where Landau damping is the dominant dissipation channel and presents an intrinsic limitation to plasmonics technology. We show that …

Effects Of Surface States, Defects And Dopants On The Optical And Magnetic Properties Of Low-Dimensional Materials, Ramakrishna Podila

All Dissertations

Nanomaterials have attracted the attention of researchers from various fields due to their unique features (that are otherwise absent in the bulk) such as quantum confinement, high surface to volume ratio, ability for surface modification etc. Since the discovery of fullerenes and carbon nanotubes, several synthesis techniques have been developed for nanomaterial growth. However, different control parameters in different synthesis techniques often result in nanostructures with varying defects that may alter their fundamental behavior. Such defects or disorder in the crystal lattice can lead to the disruption of lattice symmetry. The defect-induced symmetry lowering (or breaking) effects play a vital …

Band Structures Of Layered Carbon/Boron Nitride Materials With Commensurate Lattices, Christopher C. Wells

Legacy Theses & Dissertations (2009 - 2024)

The electronic structures of systems consisting of hexagonal boron nitride layers and graphite sheets have been investigated in detail using density functional theory methods with two exchange correlation functions (local density approximation and generalized gradient approximation). The experimental data of graphene, graphite, monolayer hexagonal BN, and hexagonal BN were reproduced well with computational models. The commensurate models used in the investigation were generated by taking the averages of the lattice constants for graphite and h-BN.

Growth And Characterization Of Carbon Nanomaterials, Jay Patel

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In this thesis, single and multi-layered graphene films were epitaxially grown on either Si-face or C-face of SiC single crystal substrates. The film growth conditions, such as decomposition temperatures and pressures, and their surface morphologies were optimized. These films were then characterized by using surface analysis tools including SEM, TEM, AFM evanescent wave microscopy and electron educed spectroscopy. In addition to studying graphene decomposed from SiC crystals, carbon nanotube material was fabricated using a floating catalyst technique. These carbon nanotube material was then studied for potential cathode applications in this thesis. Field emission properties of these cathodes was measured and …

Theory Of Electronic And Optical Properties Of Nanostructures, Prabath Hewageegana

Physics and Astronomy Dissertations

"There is plenty of room at the bottom." This bold and prophetic statement from Nobel laureate Richard Feynman back in 1950s at Cal Tech launched the Nano Age and predicted, quite accurately, the explosion in nanoscience and nanotechnology. Now this is a fast developing area in both science and technology. Many think this would bring the greatest technological revolution in the history of mankind. To understand electronic and optical properties of nanostructures, the following problems have been studied. In particular, intensity of mid-infrared light transmitted through a metallic diffraction grating has been theoretically studied. It has been shown that for …

Electron Beam Characterization Of Carbon Nanostructures, Eric Samuel Mandell

Doctoral Dissertations

"Atom-thick carbon nanostructures represent a class of novel materials that are of interest to those studying carbon's role in fossil fuel, hydrogen storage, scaled-down electronics, and other nanotechnology. Electron microscope images of "edge-on" graphene sheets show linear image features due to the projected potential of the sheets. Here, intensity profiles along these linear features can measure the curvature of the sheet, as well as the shape of the sheet (i.e. hexagonal, triangular). Also, electron diffraction powder profiles calculated for triangular graphene sheet shapes show a broadening of the low frequency edge of diffraction rings, in comparison to those calculated for …

Electronic Properties Of Silicon-Based Nanostructures, Gian Giacomo Guzman-Verri

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We have developed a new unifying tight-binding theory that can account for the electronic properties of recently proposed Si-based nanostructures, namely, Si graphene-like sheets and Si nanotubes. We considered the sp²s* and sp³ models up to first- and second-nearest neighbors, respectively. Our results show that the corresponding Si nanotubes follow the so-called Hamada's rule. Comparison to a recent ab initio calculation is made.