Engineering Commons^™

Modeling Of Thermally Aware Carbon Nanotube And Graphene Based Post Cmos Vlsi Interconnect, K M Mohsin

LSU Doctoral Dissertations

This work studies various emerging reduced dimensional materials for very large-scale integration (VLSI) interconnects. The prime motivation of this work is to find an alternative to the existing Cu-based interconnect for post-CMOS technology nodes with an emphasis on thermal stability. Starting from the material modeling, this work includes material characterization, exploration of electronic properties, vibrational properties and to analyze performance as a VLSI interconnect. Using state of the art density functional theories (DFT) one-dimensional and two-dimensional materials were designed for exploring their electronic structures, transport properties and their circuit behaviors. Primarily carbon nanotube (CNT), graphene and graphene/copper based interconnects were …

Computational Studies Of Structure–Function Relationships Of Supported And Unsupported Metal Nanoclusters, Hongbo Shi

Doctoral Dissertations

Fuel cells have been demonstrated to be promising power generation devices to address the current global energy and environmental challenges. One of the many barriers to commercialization is the cost of precious catalysts needed to achieve sufficient power output. Platinum-based materials play an important role as electrocatalysts in energy conversion technologies. In order to improve catalytic efficiency and facilitate rational design and development of new catalysts, structure–function relationships that underpin catalytic activity must be understood at a fundamental level. First, we present a systematic analysis of CO adsorption on Pt nanoclusters in the 0.2-1.5 nm size range with the aim …

Solution-Based Assembly Of Conjugated Polymers Into Nanofibers For Organic Electronics, Daniel E. Acevedo Cartagena

Doctoral Dissertations

Solution-based crystallization of conjugated polymers offers a scalable and attractive route to develop hierarchical structures for electronic devices. The introduction of well-defined nucleation sites into metastable solutions provides a way to regulate the crystallization behavior, and therefore the morphology of the material. A crystallization method for generating metastable solutions of poly(3-hexylthiophene) (P3HT) was established. These metastable solutions allow P3HT to selectively crystallize into nanofibers (NFs) on graphene-coated surfaces. It was found that the crystallization kinetics is faster with increasing P3HT molecular weight and concentration. Through in situ atomic force microscopy, it was confirmed that NFs grow vertically in a face-on …

Interactions At The Aqueous Interface Of Large-Area Graphene: Colloidal-Scale And Protein Adsorption, Aaron Chen

Doctoral Dissertations

This thesis addresses the interactive interfacial character of large-area supported graphene in an aqueous environment near neutral pH. Studies of molecular bio-interactions with proteins and colloidal interactions with microparticles probe the role of hydrophobicity, van der Waals, and electrostatic contributions with varied ionic strength. The respective roles of the silica support and the graphene itself are identified. Results are benchmarked against other systems directly in experiments, and against published behavior with other materials, especially self-assembled monolayers. The adhesive and adsorption behavior of supported graphene is also put into context by calculations of surface and interaction potentials. Interest in graphene is …

Two Dimensional Layered Materials And Heterostructures, A Surface Science Investigation And Characterization, Yujing Ma

USF Tampa Graduate Theses and Dissertations

The isolation of single layers of van der Waals materials has shown that their properties can be significantly different compared to their bulk counterparts. These observations, illustrates the importance of interface interactions for determining the materials properties even in weakly interacting materials and raise the question if materials properties of single layer van der Waals materials can be controlled by appropriate hetero-interfaces. To study interface effects in monolayer systems, surface science techniques, such as photoemission spectroscopy and scanning probe microscopy/spectroscopy, are ideally suited. However, before these characterization methods can be employed, approaches for the synthesis of hetero-van der Waals systems …

Fabrication And Characterization Of Hybrid Nanocomposites By Matrix Assisted Pulsed Laser Evaporation, Songlin Yang

Electronic Thesis and Dissertation Repository

Different methods have been applied to deposit hybrid nanocomposites which can be applied in various fields due to their light weight and multifunctional properties. Here, matrix assisted pulsed laser evaporation (MAPLE) equipment with 532 nm Nd:YAG laser is applied to fabricate three types of hybrid nanocomposites on different substrates.

Chemical synthesized FeCo nanoparticles were deposited on graphene sheets by MAPLE technique (laser fluence: 300 mJ/cm²). The effects of deposition time (t) on particle amount, shape and size have been investigated. Yttrium barium copper oxide (YBCO) materials are one type of high-temperature superconductive materials and …

Graphite And Graphene-Oxide Based Pgm-Free Model Catalysts For The Oxygen Reduction Reaction, Joseph Henry Dumont

Nanoscience and Microsystems ETDs

The world currently relies heavily on fossil fuels such as coal, oil, and natural gas for its energy. Fossil fuels are non-renewable, that is, they draw on finite resources that will eventually dwindle, becoming too expensive or too environmentally damaging to retrieve. One alternative source of energy are fuel cells, electrochemical devices that convert chemical energy to cleanly and efficiently produce electricity. They can be used in a wide range of applications, including transportation, stationary, portable and emergency power sources. Their development has been slowed by the high cost of PGM electrocatalysts needed at both electrodes as well as sluggish …

Drawing And Twisting Of Graphene Fibers, Gregory T. Lane, Robert J. Sekerak, Isaias Diaz

Mechanical Engineering

The aim of this project was to develop a more automated process for drawing and twisting of graphene fibers than was currently in place. This was implemented by having two chemical baths with variable speed rollers at either end, and intermediate roller to spool fiber between stages, and a twisting cylinder with integral spool to twist the fiber as it is collected. The goal was to have this first iteration deliver a working prototype, however due to manufacturing delays and timing constraints, that will be missed. A second follow-on project would be able to continue the work presented here and …

Surface Energy In Bond-Counting Models On Bravais And Non-Bravais Lattices, Tim Ryan Krumwiede

Doctoral Dissertations

Continuum models in computational material science require the choice of a surface energy function, based on properties of the material of interest. This work shows how to use atomistic bond-counting models and crystal geometry to inform this choice. We will examine some of the difficulties that arise in the comparison between these models due to differing types of truncation. New crystal geometry methods are required when considering materials with non-Bravais lattice structure, resulting in a multi-valued surface energy. These methods will then be presented in the context of the two-dimensional material graphene in a way that correctly predicts its equilibrium …

Dft Study Of Adsorption Of Trimetallic Endohedral Fullerenes On Graphene, Nakul Nitin Karle

Open Access Theses & Dissertations

A density functional theory (DFT) study on the geometric and electronic structure of C60 and Sc3N@C80 along with their adsorption on pristine single layer graphene (SLG) is presented. C60 is found to adsorb in two nearly degenerate configurations: (i) with a pentagon facing the SLG, which is the most stable one, and (ii) with a hexagon facing the SLG in a face-to-face perfect alignment, rarely common in Ï?â??Ï? interactions, 0.06 eV higher in energy. The calculated binding energy of 0.76 eV, which includes dispersion effects, is in good agreement with previous theoretical and experimental reports. On the contrary, Sc3N@C80 adsorption …

Graphene Nano-Composites For Hypervelocity Impact Applications, Alharith Manasrah

Electronic Theses and Dissertations

The Low Earth Orbit (LEO) is a harsh environment cluttered with natural meteoroids and man-made debris, which can travel at velocities approaching 15 km/s. Most space activities within the LEO will encounter this environment. Thus, the spacecraft and its hardware must be designed to survive debris impact. This research introduces new procedures to produce a nano-composite material with mortar-brick nano-structure inspired from nacre. Nacre-like composites were successfully manufactured, based on three host polymers, with a wide range of graphene concentrations. The manufactured exfoliated graphene nano-platelet, embedded in a host polymer, provided good potential for enhancement of the hypervelocity impact (HVI) …

Biphasic Cellulose Acetate/Rtil Membranes And Functionalized Graphene Adsorbents For Natural Gas Processing: Experimental And Molecular Simulation Studies, Amir Khakpay

Electronic Theses and Dissertations

In this dissertation, gas separation using membranes is investigated for natural gas upgrading. The main objectives of this study are separation of high value hydrocarbons such as propane (c3h8) from natural gas and carbon dioxide (co2) separation from light gases such as nitrogen (n2) and methane (ch4). To achieve these goals, supported ionic liquid membranes (silms), biphasic membranes, and nanoporous graphene (npg) and graphene oxide (npgo) membranes are studied. Biphasic membranes are proposed to overcome silms issues for gas separation. The major issues with silms are low room temperature ionic liquid (rtil) content and instability at high cross-membrane pressure. For …

Multiscale Modeling: Thermal Conductivity Of Graphene/Cycloaliphatic Epoxy Composites, Sorayot Chinkanjanarot

Dissertations, Master's Theses and Master's Reports

The thermal property of epoxy as the binder in the Carbon Fiber (CF) composites, especially thermal conductivity is important to achieve the advance technology and to improve the performance of materials. Multiscale modeling including molecular dynamic (MD) modeling and micromechanical modeling is used to study the properties of neat Cycloaliphatic Epoxies (CE) and Graphene nanoplatelet (GNP)/CE with and without covalent functionalization.

The thermal properties (glass-transition temperature, thermal expansion coefficient, and thermal conductivity) and mechanical properties of CE system are investigated by MD modeling using OPLS-All Atom force field. A unique crosslinking technique is developed to achieve the cured CE models …

Effect Of Interlayers On Mechanical Properties And Interfacial Stress Transfer Of 2d Layered Graphene-Polymer Nanocompsites, Colton C. Roach

Theses and Dissertations--Mechanical Engineering

Graphene, a monolayer of sp²-hybridized carbon atoms arranged in a two-dimensional (2D) lattice, is one of the most important 2D nanomaterials and has attracted tremendous attentions due to its unique geometric characteristics and exceptional mechanical properties. One of the most promising applications of this 2D nanomaterial is in polymer nanocomposites, in which the ultra-stiff, ultra-thin graphene layers function as reinforcement fillers. However, two significant questions remain to be answered: (1) whether the mechanical behaviors of 2D graphene reinforced nanocomposites can be analyzed by the convention composite theory, which is developed primarily for one-dimensional (1D) fiber-type of fillers, and …

Low-Cost Inkjet-Printed Flexible Circuit For Gas Sensing, Sm Mehedee Parvez

All ETDs from UAB

ABSTRACT Logistics management is a major section of a stable business plan. It is responsible for planning, implementing, and controlling the production and distribution processes of the goods. Its function is even more crucial when goods, which are being handled, are perishable products like food and medicine. It is known in the food industry that a large amount of food is wasted during the transportation chain. More often than not, the main reason for foods going spoiled stems from the presence of unwanted gases around the area of storing. Accurate monitoring and controlling of the environmental conditions imposed on perishable …

Modeling Of Two Dimensional Graphene And Non-Graphene Material Based Tunnel Field Effect Transistors For Integrated Circuit Design, Md Shamiul Fahad

LSU Doctoral Dissertations

The Moore’s law of scaling of metal oxide semiconductor field effect transistor (MOSFET) had been a driving force toward the unprecedented advancement in development of integrated circuit over the last five decades. As the technology scales down to 7 nm node and below following the Moore’s law, conventional MOSFETs are becoming more vulnerable to extremely high off-state leakage current exhibiting a tremendous amount of standby power dissipation. Moreover, the fundamental physical limit of MOSFET of 60 mV/decade subthreshold slope exacerbates the situation further requiring current transport mechanism other than drift and diffusion for the operation of transistors. One way to …

Study Of Mos2 And Graphene-Based Heterojunctions For Electronic And Sensing Applications, Ifat Jahangir

Theses and Dissertations

Since the discovery of graphene, there has been an increase in two-dimensional (2D) materials research for their scalability down to atomic dimensions. Among the analogs of graphene, transition metal dichalcogenides (TMDs) are attractive due to their exceptional electronic and optoelectronic properties. MoS2, a TMD, has several advantages over graphene and the industry workhorse Si, and has been reported to demonstrate excellent transistor performances. The key obstacle in the commercialization of MoS2 technology is low carrier mobility over large areas for top-down devices. Although there were several early reports on synthesis of atomically thin MoS2 with moderate mobility, transferring large area …

Aperiodic Multilayer Graphene Based Tunable And Switchable Thermal Emitter At Mid-Infrared Frequencies, Safura Sharifi

LSU Master's Theses

Over the past few decades, there have been tremendous innovations in electronics and photonics. The development of these ultra-fast growing technologies mostly relies on fundamental understanding of novel materials with unique properties as well as new designs of device architectures with more diverse and better functionalities. In this regard, the promising approach for next-generation nanoscale electronics and photonics is to exploit the extraordinary characteristics of novel nanomaterials. There has been an explosion of interest in graphene for photonic applications as it provides a degree of freedom to manipulate electromagnetic waves. In this thesis, to tailor the broadband blackbody radiation, new …

Advanced Carbon Materials Based Electrodes For High Performance Symmetric Supercapacitors, Keliang Wang

Electronic Theses and Dissertations

Supercapacitors have received considerable attention due to their high energy density, long life time, rapid charge/discharge rate, and because they are environmental friendly technology. Electrode materials play a key role in the final performance of supercapacitors. Carbon, usually used as symmetric supercapacitors electrode materials, exhibit extraordinary stability in harsh electrolyte and electrochemical performance owing to its physical and chemical properties. In addition, porous structure originated from activation, excellent electrical conductivity, sustainability, wide availability and low cost further offering the improvement in electrochemical performance and make it to be a promising electrode material for symmetric supercapacitors. Considering the factors affected electrochemical …

Photo-Effects On Current Transport In Back-Gate Graphene Field-Effect Transistor, Xinlu Chen

LSU Master's Theses

Graphene, which has attracted wide attention because of its two-dimensional structure and high carrier mobility, is a promising candidate for potential application in optics and electronics. In this dissertation, the photonic effects on current transport in back-gate graphene field-effect transistor is investigated. Chemical vapor deposition (CVD) on metal provides a promising way for large area, controllability and high quality graphene film. The transfer and back-gate transistor fabrication processes are proposed in this dissertation. The theoretical analysis of photodetector based on back-gate graphene field-effect transistor has been done. It is shown that the photo-electronic current consists of current contributions from photovoltaic, …