Engineering Commons^™

Nitrogen Radiofrequency Plasma Treatment Of Graphene, Antoine Bident, Nathalie Caillault, Florence Delange, Christine Labrugere, Guillaume Aubert, Cyril Aymonier, Etienne Durand, Alain Demourgues, Yongfeng Lu, Jean-François Silvain

Department of Electrical and Computer Engineering: Faculty Publications

The incorporation of nitrogen (N) atoms into a graphitic network such as graphene (Gr) remains a major challenge. However, even if the insertion mechanisms are not yet fully understood, it is certain that the modification of the electrical properties of Gr is possible according to the configuration adopted. Several simulations work, notably using DFT, have shown that the incorporation of N in Gr can induce an increase in the electrical conductivity and N acts as an electron donor; this increase is linked to the amount of N, the sp²/sp³ carbon configuration, and the nature of C-N bonding. …

A Molecular Dynamics Study Of Water Confined In Between Two Graphene Sheets Under Compression, Ming-Lang Tseng, Ayomide Adesiyan, Abdelaziz Gassoumi, Nima E. Gorji

Articles

Several studies have demonstrated interest in creating surfaces with improved water interaction and adaptive properties because the behavior of water confined at the nanoscale plays a significant role in the synthesis of materials for technological applications. Remarkably, confinement at the nanoscale significantly modifies the characteristics of water. We determine the phase diagram of water contained by graphene stack sheets in slab form, at T=300 K, and for a constant pressure using molecular dynamics simulations. We discover that, as shown in the simulation, water can exist in both the liquid and vapor phases depending on the confining geometry and compressibility ratio. …

Nonreciprocal Electromagnetics Of Layered Media, Samaneh Pakniyat

Theses and Dissertations

In plasmonic systems, interaction of light and surface plasmons leads to excitation of surface plasmon polaritons (SPPs) carrying energy on the surface. In an isotropic plasmonic system, the SPPs optical response is reciprocal, which means that the forward and backward surface waves have identical propagation behaviors and SPPs refract when they encounter a discontinuity on the surface. In order to excite SPPs resilient to the surface disorders, the system reciprocity needs to be broken by different techniques such as applying an external magnetic bias. In this case, the plasmonic system becomes a gyrotropic medium. Recently, it has been shown that …

Design Tunneling Transistor And Schottky Junction Solar Cell Using Van Der Waals Semiconductor Heterostructure, Md Azmot Ullah Khan

LSU Doctoral Dissertations

Transition metal di-chalcogenide (TMDC) materials, being semiconductor in nature, offer Two-dimensional (2D) materials such as graphene and molybdenum disulfide (MoS₂) possess unique and unusual properties that are particularly applicable to nanoelectronics and photovoltaic devices. In this dissertation, four different projects have been done that encompass the implementation of these materials to improve the performance of future transistors and Schottky junction solar cells. In chapter 2, an analytical current transport model of a dual gate tunnel field-effect transistor (TFET) is developed by utilizing the principle of band-to-band tunneling (BTBT) and MoS₂ as the channel material. Later, using this …

Graphene Based Tunable Terahertz Holographic Antennas, Pengfei Ren, Lijun Jiang, Ping Li

Electrical and Computer Engineering Faculty Research & Creative Works

In this work, several representative terahertz (THz) graphene holographic impedance surface antenna are presented. Different to the conventional impedance surface antenna that manipulates the surface impedance via varying the patch size in each unit cell, the surface impedance of the proposed antenna in this paper is readily controlled by applying a tunable DC biasing to each graphene patch cell, the physics behind which is that the conductivity of the graphene is a function of imposed voltage. Thus, the graphene patches of the proposed antenna have same size as well as equal spacing, which makes the modeling process more convenient and …

Fabrication And Characterization Of Photodetector Devices Based On Nanostructured Materials: Graphene And Colloidal Nanocrystals, Wafaa Gebril

Graduate Theses and Dissertations

Photodetectors are devices that capture light signals and convert them into electrical signals. High performance photodetectors are in demand in a variety of applications, such as optical communication, security, and environmental monitoring. Among many appealing nanomaterials for novel photodetection devices, graphene and semiconductor colloidal nanocrystals are promising candidates because of their desirable and unique properties compared to conventional materials.

Photodetector devices based on different types of nanostructured materials including graphene and colloidal nanocrystals were investigated. First, graphene layers were mechanically exfoliated and characterized for device fabrication. Self-powered few layers graphene phototransistors were studied. At zero drain voltage bias and room …

Graphene As A Shielding Material For Sar Reduction In Human Head Using Rectangular And Circular Patch Antenna, Alka Singla Er., Anupma Marwaha Dr., Sanjay Marwaha Dr.

Karbala International Journal of Modern Science

Nanomaterials pave the way for better performance in wireless applications due to their unique properties. Nowadays, these have been used as shield material in dipole antennas for a solution of reduction in SAR value. This work proposes the use of emerging graphene nanomaterial by comparing the performance for two different shapes of patch antenna namely rectangular and circular patch. With the growth in technology, the protection of human health is also mandatory so the work is planned to use graphene as a shielding material for SAR reduction in the human brain and it is proved that for rectangular and circular …

Recent Advances In Terahertz Photonic Technologies Based On Graphene And Their Applications, Tianjing Guo, Christos Argyropoulos

Department of Electrical and Computer Engineering: Faculty Publications

Graphene is a unique 2D material that has been extensively investigated due to its extraordinary photonic, electronic, thermal, and mechanical properties. Excited plasmons along its surface and other unique features are expected to play an important role in many emerging photonic technologies with drastically improved and tunable functionalities. This review is focused on presenting several recently introduced photonic phenomena based on graphene, beyond its usual linear response, such as nonlinear, active, topological, and nonreciprocal effects. The physical mechanisms and various envisioned photonic applications corresponding to these novel intriguing functionalities are also reported. The presented graphene-based technologies promise to revolutionize the …

Carbon Nanotube-On-Graphene Heterostructures, Yu Zheng, Dongmeng Li, Zubair Ahmed, Jeongwon Park, Changjian Zhou, Cary Y. Yang

Electrical and Computer Engineering

This paper presents a brief review of experimental and theoretical studies on a three-dimensional heterostructure consisting of vertical carbon nanotubes (CNTs) connected perpendicularly to a graphene layer. This structure can serve as a potential building block for an all-carbon network in energy storage devices and on-chip interconnects. The review highlights reported works on the fabrication and characterization of such a heterostructure, with focus on the effect of the CNT-graphene interface on electrical conduction. While a direct comparison between experiment and theory is not possible at this time, a brief survey of theoretical efforts based on atomic cluster models nonetheless reveals …

Inkjet-Printed Graphene-Based 1 × 2 Phased Array Antenna, Mahmuda Akter Monne, Peter Mack Grubb, Harold Stern, Harish Subbaraman, Ray T. Chen, Maggie Yihong Chen

Electrical and Computer Engineering Faculty Publications and Presentations

Low-cost and conformal phased array antennas (PAAs) on flexible substrates are of particular interest in many applications. The major deterrents to developing flexible PAA systems are the difficulty in integrating antenna and electronics circuits on the flexible surface, as well as the bendability and oxidation rate of radiating elements and electronics circuits. In this research, graphene ink was developed from graphene flakes and used to inkjet print the radiating element and the active channel of field effect transistors (FETs). Bending and oxidation tests were carried out to validate the application of printed flexible graphene thin films in flexible electronics. An …

Free Charge Carrier Properties In Two-Dimensional Materials And Monoclinic Oxides Studied By Optical Hall Effect, Sean Knight

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

In this dissertation, optical Hall effect (OHE) measurements are used to determine the free charge carrier properties of important two-dimensional materials and monoclinic oxides. Two-dimensional material systems have proven useful in high-frequency electronic devices due to their unique properties, such as high mobility, which arise from their two-dimensional nature. Monoclinic oxides exhibit many desirable characteristics, for example low-crystal symmetry which could lead to anisotropic carrier properties. Here, single-crystal monoclinic gallium oxide, an AlInN/GaN-based high-electron-mobility transistor (HEMT) structure, and epitaxial graphene are studied as examples. To characterize these material systems, the OHE measurement technique is employed. The OHE is a physical …

Tunable Compact Thz Devices Based On Graphene And Other 2d Material Metasurfaces, Tianjing Guo

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Since the isolation of graphene in 2004, a large amount of research has been directed at 2D materials and their applications due to their unique characteristics. Compared with the noble metal plasmons in the visible and near-infrared frequencies, graphene can support surface plasmons in the lower frequencies of terahertz (THz) and midinfrared. Especially, the surface conductivity of graphene can be tuned by either chemical doping or electrostatic gating. As a result, the idea of designing graphene metasurfaces is attractive because of its ultra-broadband response and tunability.

It has been demonstrated theoretically and experimentally that the third-order nonlinearity of graphene at …

The Hybridization Of A Graphene And Silicon Carbide Schottky Optoelectronic Device By The Incorporation Of A Lead Sulfide Quantum Dot Film, Joshua Letton

Theses and Dissertations

The work that follows examines the impact of lead sulfide quantum dots on a native epitaxial graphene (EG) SiC Schottky device, resulting in a hybrid optoelectronic device which presents a possible avenue towards a novel hybrid carbide-based Schottky solar cell. The active (n-type SiC) and contact (graphene) layers for the Schottky junction of the device were grown epitaxially using a novel technique incorporating tetrafluorosilane (TFS) as a precursor gas. The bare EG/SiC device was characterized based on its I-V behavior in dark and under illumination for both forward and reverse bias conditions. The initial characterization demonstrated the expected Schottky diode …

Ordered Mesoporous Carbon/Graphene/Nickel Foam For Flexible Dopamine Detection With Ultrahigh Sensitivity And Selectivity, Lai-Yu Wang, Xin Xi, Dong-Qing Wu, Xiong-Yu Liu, Wei Ji, Rui-Li Liu

Journal of Electrochemistry

Flexible biosensors have received intensive attentions for their potential applications in wearable electronics. To obtain flexible electrochemical dopamine (DA) sensors, the ordered mesoporous carbon/graphene/nickel foam (OMC/G/Ni) composite was fabricated in this work via the growth of graphene on Ni foam by chemical vapor deposition, and the formation of the OMC layer followed by the carbonization of co-assembled resol and block polymer., The monolithic Ni foam in the resultant OMC/G/Ni electrode provided an interconnected metal framework with high conductivity and good flexibility, while the OMC layer with the vertically aligned mesopore arrays rendered the composite a large electroactive surface with highly …

Tunneling And Transport Properties Of Organic And Inorganic Thin Film, Farhana Anwar

Electrical and Computer Engineering ETDs

In this article I provide a new method for computing electronic transport properties of graphene i.e. the peculiar tunneling properties of two-dimensional massless Dirac electrons. I consider a simple situation : a massless Dirac electron incident on a potential barrier which is tilted by applied bias and use finite difference method to obtain transmission probability(without involving transfer matrix). In the presence of an applied bias transmission coefficient and tunneling current were obtained and the effect of electric field which modulates the barrier profile therefore conductivity pattern were explained. Furthermore, this method can also be applied to investigate transport properties of …

Carbon-Based Interlayers In Perovskite Solar Cells, Aleksandr P. Litvin, Xiaoyu Zhang, Kevin Berwick, Anatoly V. Fedorov, Weitao Zheng, Alexander V. Baranov

Articles

Perovskites are solution-processed, high-performance semiconductors of interest in low-cost photovoltaics. The interfaces between the perovskite photoactive layers and the top and bottom contacts are crucial for efficient charge transport and minimizing trapping. Control of the collection of charge carriers at these interfaces is decisive to device performance. Here, we review recent progress in the realization of efficient perovskite solar cells using cheap, easily processed, stable, carbon-based interlayers. Interface materials including graphene, carbon nanotubes, fullerenes, graphene quantum dots and carbon dots are introduced and their influence on device performance is discussed.

A Preliminary Study Of A Graphene Fractal Sierpinski Antenna, Alberto Boretti, Lorenzo Rosa, Jonathan Blackledge, Stefania Castelletto

Conference papers

We provide a preliminary study of a Graphene fractal antenna operating at THz frequencies with the opportunity to modulate the emission. There are a number of advantages of the fractal design, namely multiband/wideband ability, and, a smaller, lighter and simpler configuration for higher gain, that can benefit from the coupling with Graphene, the thinnest and strongest of materials exhibiting very high electrical conductivity and tunability. This paper proposes a conceptual background for the study and presents some preliminary results on the electromagnetic emission simulations undertaken

Numerical Methods For Electromagnetic Modeling Of Graphene: A Review, Kaikun Niu, Ping Li, Zhixiang Huang, Li (Lijun) Jun Jiang, Hakan Bagci

Electrical and Computer Engineering Faculty Research & Creative Works

Graphene's remarkable electrical, mechanical, thermal, and chemical properties have made this the frontier of many other 2-D materials a focus of significant research interest in the last decade. Many theoretical studies of the physical mechanisms behind these properties have been followed by those investing the graphene's practical use in various fields of engineering. Electromagnetics, optics, and photonics are among these fields, where potential benefits of graphene in improving the device/system performance have been studied. These studies are often carried out using simulation tools. To this end, many numerical methods have been developed to characterize electromagnetic field/wave interactions on graphene sheets …

Synthesis Of Graphene Using Plasma Etching And Atmospheric Pressure Annealing: Process And Sensor Development, Andrew Robert Graves

Graduate Theses, Dissertations, and Problem Reports

Having been theorized in 1947, it was not until 2004 that graphene was first isolated. In the years since its isolation, graphene has been the subject of intense, world-wide study due to its incredibly diverse array of useful properties. Even though many billions of dollars have been spent on its development, graphene has yet to break out of the laboratory and penetrate mainstream industrial applications markets. This is because graphene faces a ‘grand challenge.’ Simply put, there is currently no method of manufacturing high-quality graphene on the industrial scale. This grand challenge looms particularly large for electronic applications where the …

Gamma-Ray Radiation Effects In Graphene-Based Transistors With H-Bn Nanometer Film Substrates, E. J. Cazalas, Michael R. Hogsed, S. R. Vangala, Michael R. Snure, John W. Mcclory

Faculty Publications

Radiation effects on graphene field effect transistors (GFETs) with hexagonal boron nitride (h-BN) thin film substrates are investigated using 60Co gamma-ray radiation. This study examines the radiation response using many samples with varying h-BN film thicknesses (1.6 and 20 nm thickness) and graphene channel lengths (5 and 10 μm). These samples were exposed to a total ionizing dose of approximately 1 Mrad(Si). I-V measurements were taken at fixed time intervals between irradiations and postirradiation. Dirac point voltage and current are extracted from the I-V measurements, as well as mobility, Dirac voltage hysteresis, and the total number of GFETs that remain …

Unidirectional And Nonreciprocal Nanophotonic Devices Based On Graphene And Magneto-Optical Materials, Vahid Foroughi Nezhad

LSU Doctoral Dissertations

In this dissertation, we first introduce compact tunable spatial mode converters for graphene parallel plate (GPP) waveguides. The converters are reciprocal and based on spatial modulation of graphene’s conductivity. The wavelength of operation of the mode converters is tunable in the mid-infrared wavelength range by adjusting the chemical potential of a strip on one of the graphene layers of the GPP waveguides. We also introduce optical diodes for GPP waveguides based on a spatial mode converter and a coupler, which consists of a single layer of graphene placed in the middle between the two plates of two GPP waveguides. \par …

Surface-Enhanced Raman Detection Of Glucose On Several Novel Substrates For Biosensing Applications, Laila Saad Alqarni

Dissertations

The small normal Raman cross-section of glucose is considered to be a major challenge for its detection by Surface Enhanced Raman Spectroscopy (SERS) for medical applications. These applications include blood glucose level monitoring of diabetic patients and evaluation of patients with other medical conditions, since glucose is a marker for many human diseases. This dissertation focuses on Surface-Enhanced Raman Scattering primarily for the detection of glucose. Some experiments also are carried out for the detection of the corresponding enzyme glucose oxidase that is used in electrochemical glucose sensors and in biofuel cells. This project explores the possibility of utilizing Surface …

Exploring The Electrical Properties Of Twisted Bilayer Graphene, William Shannon

Senior Theses

Two-dimensional materials exhibit properties unlike anything else seen in conventional substances. Electrons in these materials are confined to move only in the plane. In order to explore the effects of these materials, we have built apparatus and refined procedures with which to create two-dimensional structures. Two-dimensional devices have been made using exfoliated graphene and placed on gold contacts. Their topography has been observed using Atomic Force Microscopy (AFM) confirming samples with monolayer, bilayer, and twisted bilayer structure. Relative work functions of each have been measured using Kelvin Probe Force Microscopy (KPFM) showing that twisted bilayer graphene has a surface potential …

Plasmonic Properties Of Nanoparticle And Two Dimensional Material Integrated Structure, Desalegn Tadesse Debu

Graduate Theses and Dissertations

Recently, various groups have demonstrated nano-scale engineering of nanostructures for optical to infrared wavelength plasmonic applications. Most fabrication technique processes, especially those using noble metals, requires an adhesion layer. Previously proposed theoretical work to support experimental measurement often neglect the effect of the adhesion layers. The first finding of this work focuses on the impact of the adhesion layer on nanoparticle plasmonic properties. Gold nanodisks with a titanium adhesion layer are investigated by calculating the scattering, absorption, and extinction cross-section with numerical simulations using a finite difference time domain (FDTD) method. I demonstrate that a gold nanodisk with an adhesive …

Study Of Charge Carrier Transport In Graphene And Graphite As Two Dimensional And Quasi-Two Dimensional Materials And Their Interfaces, Nalat Sornkhampan

FIU Electronic Theses and Dissertations

Evidence of superconductivity in phosphorous-doped graphite and graphene has been observed at temperatures in the vicinity of 260 K. This evidence includes transport current, magnetic susceptibility, Hall and Nernst measurements. All of these measurements indicate a transition of a type II superconductor without a phase of type I until below the limits of the measurement capabilities.

Vortex states are inferred from periodically repeated steps in the R vs. T characteristics of Highly Oriented Pyrolytic Graphite and exfoliated doped multilayer graphene. The presence of vortices has been confirmed with thermal gradient driven Nernst measurements. Magnetic susceptibility measurements have shown results qualitatively …

Quantifying Thermal Boundary Conductance Of 2d–3d Interfaces, Zlatan Aksamija, Cameron J. Foss

Zlatan Aksamija

Graphene Based Functional Devices: A Short Review, Rong Wang, Xin Gang Ren, Ze Yan, Li (Lijun) Jun Jiang, Wei E.I. Sha, Guang Cun Shan

Electrical and Computer Engineering Faculty Research & Creative Works

Graphene is an ideal 2D material system bridging electronic and photonic devices. It also breaks the fundamental speed and size limits by electronics and photonics, respectively. Graphene offers multiple functions of signal transmission, emission, modulation, and detection in a broad band, high speed, compact size, and low loss. Here, we have a brief view of graphene based functional devices at microwave, terahertz, and optical frequencies. Their fundamental physics and computational models were discussed as well.

Dual Graphene Patch Antenna For Ka Band Satellite Applications, Mohammed Amin Rabah, Mohammed Bekhti

International Journal of Aviation, Aeronautics, and Aerospace

Currently; grapheme offers a new opportunity to use in space technology and this is due to its amazing properties like conductivity, strength, flexibility and transparency which allows us to exploit new generation of ultra-fast nanoscale components; Since future wireless communication techniques are geared towards the use of the high frequency spectrum and many recent research prove this trend. This letter presents a proposal for design of a dual graphene-based antenna to use in new communication techniques in Ka band, where the proposed antenna can work for uplink and dowlink frequencies at same time since it has return loss less then …

Exploring Two-Dimensional Graphene And Silicene In Digital And Rf Applications, Zhonghang Ji

Browse all Theses and Dissertations

Since the discovery of graphene, two-dimensional (2D) materials have attracted intensive interests in the past 15 years and there has been a growing interest in exploring new materials beyond graphene, such as silicene, germanene, etc. Numerous papers have been published to demonstrate their extraordinary electronic, optical, biological, and thermal properties which render broad applications in various fields. However, the absence of band gap in graphene and silicene prohibits their uses in digital applications. This dissertation reviews recent progress on band gap opening based on mono- and bi- layer silicene and presents a new silicon atomic structure which exhibits a 0.17 …

A Graphene/Rf Gas Sensor, Kathleen Louise Brockdorf

Browse all Theses and Dissertations

Toxic chemicals have been used as chemical warfare agents since ancient times, but World War 1 saw the beginning of modern chemical proliferation. There are many methods of detecting these agents, but the combination of high sensitivity, specificity, fast response, and small form factor is difficult to achieve. More recently, graphene has been identified as a possible sensing material for ammonia and other substances. This research documents a novel method of using graphene as a chemical sensor, utilizing a radio-frequency approach to sensing. This approach utilizes all available information from the material, such as permittivity and conductivity, instead of simply …