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Investigation Of Electrical And Magneto Transport Properties Of Reduced Graphene Oxide Thin Films, Ariful Haque

MSU Graduate Theses

Large area uniform thin films of reduced graphene oxide (RGO) was synthesized by pulsed laser deposition (PLD) technique. A number of structural properties including the defect density, average size of sp2 clusters, and degree of reduction were investigated by Raman spectroscopy and X-ray diffraction (XRD) analysis. The temperature dependent (5K - 350K) four terminal electrical transport property measurement confirms variable range hopping and thermally activated transport mechanism of the charge carriers at low (5K - 210K) and high temperature (210K - 350K) regions, respectively. The calculated localization length, density of states (DOS) near Fermi level (EF), hopping energy, and Arrhenius …

Metal Oxide Growth, Spin Precession Measurements And Raman Spectroscopy Of Cvd Graphene, Akitomo Matsubayashi

Legacy Theses & Dissertations (2009 - 2024)

The focus of this dissertation is to explore the possibility of wafer scale graphene-based spintronics. Graphene is a single atomic layer of sp2 bonded carbon atoms that has attracted much attention as a new type of electronic material due to its high carrier mobilities, superior mechanical properties and extremely high thermal conductivity. In addition, it has become an attractive material for use in spintronic devices owing to its long electron spin relaxation time at room temperature. This arises in part from its low spin-orbit coupling and negligible nuclear hyperfine interaction. In order to realize wafer scale graphene spintronics, utilization of …

Raman Spectroscopic Investigation Of Chondroitinase Abc Treatment After Spinal Cord Injury In An Organotypic Model, Shane Ruberto

Theses - ALL

This study investigated (1) the ability of an organotypic model of spinal cord injury (SCI) to recapitulate significant pathobiological events of in vivo SCI from a Raman spectroscopic perspective, and (2) the Raman spectroscopic effects of chondroitinase ABC (cABC) treatment on said model of SCI. Tissue from mouse spinal cords was excised, sectioned, and placed into culture, before being systematically injured to induce trauma. Cultures with and without cABC treatment were assessed using Raman spectroscopy at varying times post-injury. We demonstrate that Raman spectral phenomena characteristic of SCI can be observed using an organotypic model. By comparing these phenomena with …

Nano-Particles In Multi-Scale Composites And Ballistic Applications, Jason Gibson

Electronic Theses and Dissertations

Carbon nanotubes, graphene and nano sized core shell rubber particles have all been extensively researched for their capability to improve mechanical properties of thermoset resins. However, there has been a lack of research on their evaluation for energy absorption in high velocity impact scenarios, and the fundamental mechanics of their failure mechanisms during highly dynamic stress transfer through the matrix. This fundamental research is essential for laying the foundation for improvement in ballistic performance in composite armor. In hard armor applications, energy absorption is largely accomplished through delamination between plies of the composite laminate. This energy absorption is accomplished through …

Scandia And Ceria Stabilized Zirconia Based Electrolytes And Anodes For Intermediate Temperature Solid Oxide Fuel Cells: Manufacturing And Properties, Yan Chen

Electronic Theses and Dissertations

Mesoscale optical phenomena occur when light interacts with a number of different types of materials, such as biological and chemical systems and fabricated nanostructures. As a framework, mesoscale optics unifies the interpretations of the interaction of light with complex media when the outcome depends significantly upon the scale of the interaction. Most importantly, it guides the process of designing an optical sensing technique by focusing on the nature and amount of information that can be extracted from a measurement. Different aspects of mesoscale optics are addressed in this dissertation which led to the solution of a number of problems in …

Development Of Laser Spectroscopy For Elemental And Molecular Analysis, Yuan Liu

Electronic Theses and Dissertations

Laser-Induced Breakdown Spectroscopy (LIBS) and Raman spectroscopy are still growing analytical and sensing spectroscopic techniques. They significantly reduce the time and labor cost in analysis with simplified instrumentation, and lead to minimal or no sample damage. In this dissertation, fundamental studies to improve LIBS analytical performance were performed and its fusion with Raman into one single sensor was explored. On the fundamental side, Thomson scattering was reported for the first time to simultaneously measure the electron density and temperature of laser plasmas from a solid aluminum target at atmospheric pressure. Comparison between electron and excitation temperatures brought insights into the …

Techniques For Sensor-Integrated Robotic Systems: Raman Spectra Analysis, Image Guidance, And Kinematic Calibration, Luke Anthony Reisner

Wayne State University Dissertations

Robotics and sensor technology have made impressive advancements over the years. There are now robotic systems that help perform surgeries or explore the surface of Mars, and there are sensors that detect trace amounts of explosives or identify diseased human tissue. The most powerful systems integrate robots and sensors, which are natural complements to each other. Sensors can provide information that might otherwise be unavailable due to indirect robotic manipulation (e.g., images of the target environment), and robots can provide suitably precise positioning of an analytical sensor.

To have an effective sensor-integrated robotic system, multiple capabilities are needed in the …

Raman Spectroscopic Study Of Solid Solution Spinel Oxides, Brian D. Hosterman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Solid solution spinel oxides of composition MgxNi1−xCr2O4, NiFexCr2−xO4, and FexCr3−xO4 were synthesized and characterized using x-ray diffraction and Raman spectroscopy. Frequencies of the Raman-active modes are tracked as the metal cations within the spinel lattice are exchanged. This gives information about the dependence of the lattice vibrations on the tetrahedral and octahedral cations. The highest-frequency Raman-active mode, A1g, is unaffected by substitution of the divalent tetrahedral cation, whereas the lower frequency vibrations are more strongly affected by substitution of the tetrahedral cation. The change in wavenumber of many phonons is nonlinear upon cation exchange. All detected modes of MgxNi1−xCr2O4 and …

Enhancing Cnt-Composites With Raman Spectroscopy, Gregory J. Freihofer

Electronic Theses and Dissertations

Carbon Nanotubes (CNTs) have been the subject of intense research for their potential to improve a variety of material properties when developed as nano-composites. This research aims to address the challenges that limit the ability to transfer the outstanding nano-scale properties of CNTs to bulk nano-composites through Raman characterization. These studies relate the vibrational modes to microstructural characterization of CNT composites including stress, interface behavior, and defects. The formulation of a new fitting procedure using the pseudo-Voigt function is presented and shown to minimize the uncertainty of characteristics within the Raman G and D doublet. Methods for optimization of manufacturing …

Applications Of Raman Spectroscopy For Silicon Stress Characterization In Integrated Circuits, Colin Mcdonough

Legacy Theses & Dissertations (2009 - 2024)

The introduction of mechanical stress in Si-based integrated circuits (ICs), whether desired or undesired, is intrinsic to IC fabrication. The origins are diverse and result from the numerous materials, geometries, and processes involved in fabrication. These stresses can lead to such effects as delamination, void formation and migration, and fracture, and can significantly affect device performance. As a result, stress development is a major concern for reliability, process control, and device design. It is necessary to investigate and characterize the origins and levels of the induced stresses. A more complete fundamental understanding of the evolution of stress in ICs and …

Effects Of Low Energy E-Beam Irradiation On Graphene And Graphene Field Effect Transistors And Raman Metrology Of Graphene On Split Gate Test Structures, Gayathri Rao

Legacy Theses & Dissertations (2009 - 2024)

Apart from its compelling performance in conventional nanoelectronic device geometries, graphene is an appropriate candidate to study certain interesting phenomenon (e.g. the Veselago lens effect) predicted on the basis of its linear electron dispersion relation. A key requirement for the observation of such phenomenon in graphene and for its use in conventional field-effect transistor (FET) devices is the need to minimize defects such as consisting of - or resulting from - adsorbates and lattice non-uniformities, and reduce deleterious substrate effects. Consequently the investigation of the origin and interaction of defects in the graphene lattice is essential to improve and tailor …

Fabrication Of Anisotropic Nanostructures On Solid Substrates For Applications As Optically Active Surfaces, Mohan Krishna Vattipalli

Dissertations and Theses

Analysis of the vibrational energy levels in molecules using Raman Spectroscopy is a popular analytical method amongst today's optical technologies. Unlike fluorescence microscopy, the Raman emission doesn't undergo the process of photobleaching, which leads to short lived signal collection. The only downside with this approach is the small absorption cross-section resulting in a low intensity of the emission signal. One of the approaches used to boost this weak signal is Surface Enhanced Raman Spectroscopy (SERS). My research efforts have been focused on how to create a novel SERS substrate with aligned patterns of Au/Ag nanoparticle deposited metals of a particular …

Characterization Of Stress In Gan-On-Sapphire Microelectromechanical Systems (Mems) Structures Using Micro-Raman Spectroscopy, Francisco E. Parada

Theses and Dissertations

Micro-Raman (µRaman) spectroscopy is an efficient, non-destructive technique widely used to determine the quality of semiconductor materials and microelectromechanical systems. This work characterizes the stress distribution in wurtzite gallium nitride grown on c-plane sapphire substrates by molecular beam epitaxy. This wide bandgap semiconductor material is being considered by the Air Force Research Laboratory for the fabrication of shock-hardened MEMS accelerometers. µRaman spectroscopy is particularly useful for stress characterization because of its ability to measure the spectral shifts in Raman peaks in a material, and correlate those shifts to stress and strain. The spectral peak shift as a function of stress, …

Nanostructured Composite Materials Based On Carbon Nanotubes And 3-D Photonic Crystals, Jing Chen

Dissertations

Carbon nanotubes (CNT) and in particular, single-wall carbon nanotubes (SWCNT) have been extensively studied, in large part, due to their unique one-dimensional crystalline structures and related electronic and optical properties. Various polymeric composite materials, which were based on carbon nanotubes, have been also developed in an attempt to combine the properties of polymer and CNT in a single film. Such composites were mainly formed by mixing carbon nanotubes within the polymer without special emphasis on the structure and thereby, the nanoscopic properties of the resultant material.

Photonic crystals belong to a class of man-made structures aimed at manipulating the propagation …

Detection Of Residual Stress In Sic Mems Using Μ-Raman Spectroscopy, John C. Zingarelli

Theses and Dissertations

Micro-Raman (µ-Raman) spectroscopy is used to measure residual stress in two silicon carbide (SiC) poly-types: single-crystal, hexagonally symmetric 6H-SiC, and polycrystalline, cubic 3C-SiC thin films deposited on Si substrates. Both are used in micro-electrical-mechanical systems (MEMS) devices. By employing an incorporated piezoelectric stage with submicron positioning capabilities along with the Raman spectral acquisition, spatial scans are performed to reveal areas in the 6H-SiC MEMS structures that contain residual stress. Shifts in the transverse optical (TO) Stokes peaks of up to 2 cm^-1 are correlated to the material strain induced by the MEMS fabrication process through the development of phonon …

High Gain / Broadband Oxide Glasses For Next Generation Raman Amplifiers, Clara Rivero

Electronic Theses and Dissertations

Interest in Raman amplification has undergone a revival due to the rapidly increasing bandwidth requirements for communications transmission, both for long haul and local area networks, and recent developments in the telecom fiber industry and diode laser technology. In contrast to rare earth doped fiber amplifiers, for which the range of wavelengths is fixed and limited, Raman gain bandwidths are larger and the operating wavelength is fixed only by the pump wavelength and the bandwidth of the Raman active medium. In this context, glasses are the material of choice for this application due to their relatively broad spectral response, and …

Characterization Of Aligned Carbon Nanotube/Polymer Composites, Sumanth Banda

Theses and Dissertations

The main objective of this thesis is to efficiently disperse and align SWNTs in two different polymer matrices to obtain an orthotropic composite whose strength, stiffness and electrical properties depend on the orientation of the SWNTs. The SWNTs are successfully dispersed and aligned in a polyimide matrix and a polymer blend of UDMA/HDDMA. In-situ polymerization under sonication is used to disperse the SWNTs in polyimide matrix and sonication is used to disperse SWNTs in the UDMA/HDDMA matrix. In both cases, an electric field is used to align the SWNTs in the polymer matrices. In the polyimide, the SWNTs are aligned …

Towards Direct Writing Of 3-D Photonic Circuits Using Ultrafast Lasers, Arnaud Zoubir

Electronic Theses and Dissertations

The advent of ultrafast lasers has enabled micromachining schemes that cannot be achieved by other current techniques. Laser direct writing has emerged as one of the possible routes for fabrication of optical waveguides in transparent materials. In this thesis, the advantages and limitations of this technique are explored. Two extended-cavity ultrafast lasers were built and characterized as the laser sources for this study, with improved performance over existing systems. Waveguides are fabricated in oxide glass, chalcogenide glass, and polymers, these being the three major classes of materials for the telecommunication industry. Standard waveguide metrology is performed on the fabricated waveguides, …

Stress Analysis Of Silicon Carbide Microeletromechanical Systems Using Raman Spectroscopy, Stanley J. Ness

Theses and Dissertations

During the fabrication of Micro-Electro-Mechanical Systems (MEMS), residual stress is often induced in the thin films that are deposited to create these systems. These stresses can cause the device to fail due to buckling, curling, or fracture. Government and industry are looking for ways to characterize the stress during the deposition of thin films in order to reduce or eliminate device failure. Micro-Raman spectroscopy has been successfully used to analyze poly-silicon MEMS devices made with the Multi-User MEMS Process (MUMPS trade name). Micro-Raman spectroscopy was selected because it is nondestructive, fast and has the potential for in situ stress monitoring. …

Characterization Of Residual Stress In Microelectromechanical Systems (Mems) Devices Using Raman Spectroscopy, Lavern A. Starman

Theses and Dissertations

Due to the small scale of MEMS devices, the inherent residual stresses during the deposition processes can affect the functionality and reliability of the fabricated devices. Residual stress often causes device failure due to curling, buckling, or fracture. Currently, few techniques are available to measure the residual stress in MEMS devices. In this dissertation, Raman spectroscopy is used to measure and monitor the residual and induced stresses in MUMPs polysilicon MEMS devices. Raman spectroscopy was selected since it is nondestructive, fast, and provides potential in situ stress monitoring. Raman spectroscopy scans on unreleased and released MEMS fixed-fixed beams, cantilevers, and …

Laser Intensity Scaling Through Stimulated Scattering In Optical Fibers, Timothy H. Russell

Theses and Dissertations

The influence of stimulated scattering on laser intensity in fiber optic waveguides is examined. Stimulated Brillouin scattering (SBS) in long, multimode optical waveguides is found to generate a Stokes beam that propagates in the fiber LP01 mode. Additionally, the same process is found to combine multiple laser beams into a single spatially coherent source. Limitations in beam cleanup and combining are also investigated to identify ways to overcome them. The last portion of the dissertation theoretically examines suppression of stimulated Raman scattering in fibers to eliminate the restriction this imposes on the power of a fiber laser or amplifier. The …

Fourier Transform Raman Spectroscopy For Process Control In The Petroleum Industry, Kent Lawson Wise

Chemistry & Biochemistry Theses & Dissertations

As early as 1950, Raman spectroscopy was proposed as a method to determine aromatics and olefins in hydrocarbon mixtures. Until recently, extensive use of Raman spectroscopy in the characterization of hydrocarbons has not been practical due to several limitations. One early limitation to Raman analysis was the absence of a high intensity and stable excitation source. This problem has been overcome with the advent of lasers. Another limitation was the presence of fluorescence in hydrocarbon fuels when excited by visible lasers. However, the development of Fourier-transform Raman spectrometers now allows Raman spectra to be collected using near-IR lasers (e.g …

Petrochemical Analysis By Remote Fiber-Optic Raman Spectroscopy And Partial Least Squares Regression Analysis, Philip Edmund Flecher Jr.

Chemistry & Biochemistry Theses & Dissertations

A dispersive Raman system with charge coupled device (CCD) detection, distributed Bragg reflector (DBR) diode laser excitation, and a fiber optic probe has been developed for the rapid analysis of petrochemicals and fuels. Initially, mock petroleum fuels with analyte concentrations from 1.S - 16% were prepared and analyzed with the system. The inability of the original index guided diode laser to maintain a constant frequency during the mock petroleum analysis was a recurrent problem. The DBR laser was subsequently shown to have stability superior to index guided lasers, and was used in the remainder of the research.

Real gasoline samples …