Nanoscience and Nanotechnology Commons^™

Developing A Crystal Viewer Tool For Nanohub, Osiris V. Ntarugera, Gerhard Klimeck

The Summer Undergraduate Research Fellowship (SURF) Symposium

Most materials found in nature have their atoms arranged in a regular and repeated pattern known as crystalline structure; this is particularly true for metals. It is very important to understand the crystal structure of materials in order to predict their properties such as the electric conductivity, heat transfer, and more. Particularly, students and scholars in the field of material science need a way to visualize the different crystal structures. Atomic structures of elements are not visible to the naked eye. In that context, a computer based tool can be used to simulate and to visualize the crystal structures of …

Microfluidic Platform For Immobilizing Cells To Surfaces, Sze Yung Li, Arvind Raman

The Summer Undergraduate Research Fellowship (SURF) Symposium

Atomic Force Microscope (AFM) is an advanced nanotechnology tool for image mapping and cell properties measuring. One of the major challenges presented to the scientists in the field is the procedure for sample preparation. In order for a cell or virus to be measured by the AFM, it has to be firmly attached to the surface. Existing methods including chemical functionalization of surface for cells binding are often very slow process which hinders the possibility of high throughput measurement. Therefore, we propose a new method that utilizes a fluid circulation system to immobilize cells of interest to designated area to …

Mechanical Design Of Real-Time Substrate Transport Control For Stable And Efficient Thin-Film-Based Roll-To-Roll (R2r) Micro-Nanomanufacturing, Guoao Sun, Liang Pan

The Summer Undergraduate Research Fellowship (SURF) Symposium

The commercialization of electronic devices requires the high efficiency and stable mirco-nanomanufacturing processes that allow frequent design upgrades. R2R Nano is a gateway to science and engineering research that aims to impact the widespread adoption of R2R technologies for low-cost, high-volume production of high technology products on flexible substrates. However, there are lots of the mechanical and chemical factors influencing the system performance when fabricating nano-scale structures. Thus, feedback control system is increasingly playing a great role in improving the R2R performance.

The aim of my work of the project is more related to design mechanical section of the whole …

Micro Solar Thermal Energy Development And Use For Mems Power Applications, Emmanuel Ogbonnaya

Doctoral Dissertations

Increasing focus on alternative energy sources has produced significant progress across a wide variety of research areas. One particular area of interest has been solar energy. The sun represents sustainable and renewable energy source capable of meeting present energy needs without compromising the ability of future generations to meet theirs. Energy from the sun can be utilized in multiple ways. Direct rise in modern power generation typically involves either photovoltaic systems or large-scale solar thermal energy installations. While large-scale solar thermal energy generation is well advanced, there has been comparatively little research on smaller scale thermal energy collection and application. …

Hybrid Opto-Electrokinetic Technique For Micro/Nanomanipulation: Towards Application Of A Novel Non-Invasive Manipulation Technique In Microbiological Assay, Jae-Sung Kwon

Open Access Dissertations

This dissertation explores various physical mechanisms of the Rapid Electrokinetic Patterning (REP) technique suggested for rapid and precise on-chip manipulation of colloids and fluids, and bio-compatibility of the technique for biological applications. REP is a hybrid opto-electrokinetic technique that is driven by the simultaneous application of an AC electric field and a heating source. It can not only effectively transport and manipulate a fluid but also concentrate and pattern particles suspended in the fluid through the combined effect of an electrohydrodynamic flow, electrostatic colloidal interactions and an electrothermal microfluidic flow. These capabilities make REP a promising tool which can provide …

Solar Cell Temperature Dependent Efficiency And Very High Temperature Efficiency Limits, John Robert Wilcox

Open Access Dissertations

Clean renewable solar energy is and will continue to be a critically important source of electrical energy. Solar energy has the potential of meeting all of the world's energy needs, and has seen substantial growth in recent years. Solar cells can convert sun light directly into electrical energy, and much progress has been made in making them less expensive and more efficient. Solar cells are often characterized and modeled at 25 °C, which is significantly lower than their peak operating temperature. In some thermal concentrating systems, solar cells operate above 300 °C. Since increasing the temperature drastically affects the terminal …

Development Of A Multiscale Atomistic Code To Investigate Self-Organized Pattern Formation Induced By Ion Irradiation, Zhangcan Yang

Open Access Dissertations

Various self-organized patterns including ripples and quantum dots can be induced by ion beam sputtering (IBS). For the past decades, the understanding of such phenomenon has been mainly relied on the Bradley-Harper theory that attributes the formation of self-organized patterns to the interplay between roughening by curvature dependence of erosion and smoothening by surface diffusion. Recently, the development of the crater function theory has overturned this erosion-based paradigm to a redistribution-based paradigm. The theory has proved that erosion is irrelevant and negligible in the pattern formation at low and intermediate incidence angles. Despite the success, there are still some questions …

Graphene Decorated Substrates And Their Interfacial Characteristics, Anurag Kumar

Open Access Dissertations

Carbon nanotubes and graphene have been extensively studied for their excellent properties. As research on carbon expands, two major issues face the scientific community: (i) Expanding the scale of synthesis and (ii) Integration of different carbon structures for improved functionality. While significant advancements have been made in large-scale synthesis, room for improvement remains. As the scale of production increases, issues such as time, cost and energy that may otherwise not be very significant, begin to play greater roles. Thus, in order to effectively transition from laboratory prototypes to industrial products, a synthesis method that can address these issues is strongly …

Multiscale Modeling Of The Hierarchical Structure Of Cellulose Nanocrystals, Fernando Luis Dri

Open Access Dissertations

Cellulose constitutes the most abundant renewable polymeric resource available today. It considered an almost inexhaustible source of raw material, and holds great promise in meeting increasing demands for environmentally friendly and biocompatible products. Key future applications are currently under development for the automotive, aerospace and textile industries. When cellulose fibers are subjected to acid hydrolysis, the fibers yield rod-like, highly crystalline residues called cellulose nanocrystals (CNCs). These particles show remarkable mechanical and chemical properties (e.g. Young Modulus ~200 GPa) within the range of other synthetically-developed reinforcement materials. Critical to the design of these materials are fundamental material properties, many of …

Non-Silicon Mosfets And Circuits With Atomic Layer Deposited Higher-K Dielectrics, Lin Dong

Open Access Dissertations

The quest for technologies beyond 14nm node complementary metal-oxide-semiconductor (CMOS) devices has now called for research on higher-k gate dielectrics integration with high mobility channel materials such as III-V semiconductors and germanium. Ternary oxides, such as La2-xYxO3 and LaAlO3, have been considered as strong candidates due to their high dielectric constants and good thermal stability. Meanwhile, the unique abilities of delivering large area uniform thin film, excellent controlling of composition and thickness to an atomic level, which are keys to ultra-scaled devices, have made atomic layer deposition (ALD) technique an excellent choice.

In this thesis, we systematically study the atomic …

A New Angle On Microscopic Suspension Feeders Near Boundaries, Rachel E. Pepper, Marcus Roper, Sangjin Ryu, Nobuyoshi Matsumoto, Moeto Nagai, Howard A. Stone

Department of Mechanical and Materials Engineering: Faculty Publications

Microscopic sessile suspension feeders are a critical component in aquatic ecosystems, acting as an intermediate trophic stage between bacteria and higher eukaryotic taxa. Because they live attached to boundaries, it has long been thought that recirculation of the feeding currents produced by sessile suspension feeders inhibits their ability to access fresh fluid. However, previous models for the feeding flows of these organisms assume that they feed by pushing fluid perpendicular to surfaces they live upon, whereas we observe that sessile suspension feeders often feed at an angle to these boundaries. Using experiments and calculations, we show that living suspension feeders …

Negotiating The Inclusion Of Nanoscience Content And Technology In Science Curriculum: An Examination Of Secondary Teachers' Thinking In A Professional Development Project, Jennifer Gayle Wells

Dissertations and Theses

The Next Generation Science Standards represent a significant challenge for K-12 school reform in the United States in the science, technology, engineering and mathematics (STEM) disciplines (NSTA, 2012). One important difference between the National Science Education Standards (NRC, 1996) and the Next Generation Science Standards (Achieve, 2013) is the more extensive inclusion of nanoscale science and technology. Teacher PD is a key vehicle for implementing this STEM education reform effort (NRC, 2012; Smith, 2001).

The context of this dissertation study is Project Nanoscience and Nanotechnology Outreach (NANO), a secondary level professional development program for teachers that provides a summer workshop, …

Near Sputter-Threshold Gasb Nanopatterning, Osman El-Atwani, Sean Gonderman, Jean Paul Allain

Birck and NCN Publications

Nanopatterning at sputter-threshold energies with Ar irradiation of GaSb (100) surfaces is presented. Comparison with high-energy irradiations up to 1000 eV is conducted measuring in-situ the composition evolution over irradiation time at early stages (e. g., < 10(17) cm(-2)) and up to nanostructure saturation (e. g., similar to 10(18) cm(-2)). Low-energy irradiation is conducted for energies between 15-100 eV and a low-aspect ratio nanostructured dot formation is found. Furthermore, the role of oxide on GaSb is found to delay nanostructure formation and this is predominant at energies below 100 eV. In-situ quartz crystal microbalance measurements collect sputtered particles yielding the sputter rate at threshold energies indicating a correlation between erosion and surface composition consistent with recent theoretical models. Ion-induced segregation is also found and indicated by both compositional measurements of both the surface and the sputtered plume. (C) 2013 AIP Publishing LLC.

Giant Quasiparticle Bandgap Modulation In Graphene Nanoribbons Supported On Weakly Interacting Surfaces, Xueping Jiang, Neerav Kharche, Paul Kohl, Timothy B. Boykin, Gerhard Klimeck, Mathieu Luisier, Pulickel M. Ajayan, Saroj K. Nayak

Birck and NCN Publications

In general, there are two major factors affecting bandgaps in nanostructures: (i) the enhanced electron-electron interactions due to confinement and (ii) the modified selfenergy of electrons due to the dielectric screening. While recent theoretical studies on graphene nanoribbons (GNRs) report on the first effect, the effect of dielectric screening from the surrounding materials such as substrates has not been thoroughly investigated. Using large-scale electronic structure calculations based on the GW approach, we show that when GNRs are deposited on substrates, bandgaps get strongly suppressed (by as much as 1 eV) even though the GNR-substrate interaction is weak.

Quantum Hall Effect In Monolayer-Bilayer Graphene Planar Junctions, Jifa Tian, Yongjin Jiang, Isaac Childres, Helin Cao, Jiangping Hu, Yong P. Chen

Birck and NCN Publications

The Hall resistance of a homogeneous electron system is well known to be antisymmetric with respect to the magnetic field and the sign of charge carriers. We have observed that such symmetries no longer hold in planar hybrid structures consisting of partly single layer graphene (SLG) and partly bilayer graphene (BLG) in the quantum Hall (QH) regime. In particular, the Hall resistance across the SLG and BLG interface is observed to exhibit quantized plateaus that switch between those characteristic of SLG QH states and BLG QH states when either the sign of the charge carriers (controlled by a back gate) …

Metal-Assisted Etching Of Silicon Molds For Electroforming, Ralu Divan, Dan Rosenthal '14, Karim Ogando, Leonidas E. Ocola, Daniel Rosenmann, Nicolaie Moldovan

Student Publications & Research

Ordered arrays of high-aspect-ratio micro/nanostructures in semiconductors stirred a huge scientific interest due to their unique one-dimensional physical morphology and the associated electrical, mechanical, chemical, optoelectronic, and thermal properties. Metal-assisted chemical etching enables fabrication of such high aspect ratio Si nanostructures with controlled diameter, shape, length, and packing density, but suffers from structure deformation and shape inconsistency due to uncontrolled migration of noble metal structures during etching. Hereby the authors prove that a Ti adhesion layer helps in stabilizing gold structures, preventing their migration on the wafer surface while not impeding the etching. Based on this finding, the authors demonstrate …

Graphene Quantum Dots Enhanced Electrochemical Performance Of Polypyrrole As Supercapacitor Electrode, Kun Wu, Si-Zhe Xu, Xue-Jiao Zhou, Hai-Xia Wu

Journal of Electrochemistry

With an objective to develop electrode materials with high specific capacitance and good stability, a completely new nanocomposite of Polypyrrole (PPY) and graphene quantum dots (GQD) was successfully obtained through in-situ polymerization of pyrrole in the presence of GQD suspension. The obtained composites with different mass ratios were characterized by X-Ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). GQD enhanced electrochemical performance of PPY and, as supercapacitor electrodes, the PPY/GQD composites with the mass ratio of PPY to GQD at 50:1 showed a competitive specific capacitance of 485 F·g^-1 at a scan rate of …

Effects Of Nanocrystal Shape And Size On The Temperature Sensitivity In Raman Thermometry, Liangliang Chen, Kelly Rickey, Qing Zhao, Christopher Robinson, Xiulin Ruan

Birck and NCN Publications

The effects of CdSe nanocrystal (NC) shape and size on the temperature sensitivity of the Raman shift have been investigated, for the interest of Raman thermometry using NCs. For spherical CdSe NCs of diameters 2.8 nm, 3.6 nm, and 4.4 nm, the temperature sensitivities are -0.0131 cm(-1)/K, -0.0171 cm(-1)/K, and -0.0242 cm(-1)/K, respectively. This trend indicates that as the diameter increases, the effect of increasing phonon anharmonicity dominates over the effect of the decreasing thermal expansion coefficient. On the other hand, triangular NCs with a size of 4.2 nm and elongated NCs of a dimension of 4.6 nm by 14 …

Electronic And Optical Properties Of Scn And (Sc,Mn)N Thin Films Deposited By Reactive Dc-Magnetron Sputtering, Bivas Saha, Gururaj V. Naik, Vladimir P. Drachev, Alexandra Boltasseva, Ernesto Marinero, Timothy D. Sands

Birck and NCN Publications

Scandium nitride (ScN) is a rocksalt semiconductor that has attracted significant attention from various researchers for a diverse range of applications. Motivated by the prospect of using its interesting electronic structure for optoelectronic and dilute magnetic semiconductor applications, we present detailed studies of the electronic transport and optical properties of ScN and its alloys with manganese nitride (MnN). Our results suggest (a) dilute manganese doping in ScN compensates for the high n-type carrier concentrations arising due to oxygen impurities and (b) an n-type to p-type carrier type transition occurs at a composition between 5.8% and 11% Mn on Sc sites. …

Frequency Response Of Atmospheric Pressure Gas Breakdown In Micro/Nanogaps, Abbas Semnani, Ayyaswamy Venkattraman, Alina A. Alexeenko, Dimitrios Peroulis

Birck and NCN Publications

In this paper, we study gas breakdown in micro/nanogaps at atmospheric pressure from low RF to high millimeter band. For gaps larger than about 10 mu m, the breakdown voltage agrees with macroscale vacuum experiments, exhibiting a sharp decrease at a critical frequency, due to transition between the boundary- and diffusion-controlled regimes, and a gradual increase at very high frequencies as a result of inefficient energy transfer by field. For sub-micron gaps, a much lower breakdown is obtained almost independent of frequency because of the dominance of field emission. (C) 2013 AIP Publishing LLC.

Mapping The 3d Surface Potential In Bi2se3, Chris Mann, Damien West, Ireneusz Miotkowski, Yong P. Chen, Shengbai Zhang, Chih-Kang Shih

Birck and NCN Publications

Bi2Se3 initially emerged as a particularly promising host of topological physics. However, in actual materials, several issues have been uncovered including strong surface band bending and potential fluctuations. To investigate these concerns, we study nominally stoichiometric Bi2Se3 using scanning tunnelling microscopy. Here we identify two distinct distributions of Bi-Se antisites that act as nanometer-scale sensors for the surface band-bending field. To confirm this, we examine bulk Cu-doped Bi2Se3 and demonstrate a significantly reduced surface band-bending field. In addition, we find that in the case of unintentionally doped Bi2Se3, lateral fluctuations of the Dirac point can be directly correlated with specific …

A Humidity-Sensitive Hydrogel-Bacillus Spore Composite For Micropatterning Of Biomolecular Gradients, Richard L. Gieseck, Bin-Da Chan, Cagri A. Savran

Birck and NCN Publications

A composite material consisting of Bacillus subtilis spores suspended in a humidity sensitive hydrogel can be used to pattern biomolecules in different concentrations directly onto glass surfaces using a mechanical micromanipulator. By altering the relative humidity surrounding the composite gel during deposition, surface concentration of patterned biomolecules can be controlled and varied to create user-defined, biomolecular surface concentrations. (C) 2013 AIP Publishing LLC.

Structural Properties Of Ferroelectric Lead (Zirconium0.5,Titanium0.5)Oxygen3 Nanotube Array And Electronic Structure Of Lao Delta-Doped Strontium Titanate, Rajendra Prasad Adhikari

Graduate Theses and Dissertations

In this Dissertation we begin with two introductions on: 1) ferroelectricity and related phenomena, and 2) novel properties of Oxide electronics and the generation of two dimensional electron gas. We then give theoretical background of density functional theory (including LDA+U) and pseudopotentials. The first part of research work is about structural, polarization, and dielectric properties of ferroelectric Lead Zirconate Titanate (PZT) solid solution in the form of a nanotube array, embedded in a matrix medium of different ferroelectric strengths. We use the effective Hamiltonian derived from first-principles and finite-temperature Monte Carlo methods to determine the various properties. We revealed different …

Multiscale Study Of Batio3 Nanostructures And Nanocomposites, Lydie Louis Louis

Graduate Theses and Dissertations

Advancements in integrated nanoelectronics will continue to require the use of unique materials or systems of materials with diverse functionalities in increasingly confined spaces.

Hence, research on finite-dimensional systems strive to unearth and expand the knowledge of fundamental physical properties in certain key materials which exhibit numerous concurrent and exploitable functions.

Correspondingly, ferroelectric nanostructures, which particularly display a plethora of complex phenomena, prevalent in countless fields of research, are noteworthy candidates. Presently, however, the assimilation of zero-(0D) and one-dimensional (1D) ferroelectric into micro- or nano-electronics has been lagging, in part due to a lack of applied and fundamental studies but …

Theranostic Nanoparticles For The Treatment Of Cancer, Thomas Moore

All Dissertations

The main focus of this research was to evaluate the ability of a novel multifunctional nanoparticle to mediate drug delivery and enable a non-invasive approach to measure drug release kinetics in situ for the treatment of cancer. These goals were approached by developing a nanoparticle consisting of an inorganic core (i.e. gadolinium sulfoxide doped with europium ions or carbon nanotubes). This was coated with an external amphiphilic polymer shell comprised of a biodegradable polyester (i.e. poly(lactide) or poly(glycolide)), and poly(ethylene glycol) block copolymer. In this system, the inorganic core mediates the imaging aspect, the relatively hydrophobic polyester encapsulates hydrophobic anti-cancer …

The Legitimation Of Novel Technologies: The Case Of Nanotechnology, Anastasia E. Thyroff

Graduate Theses and Dissertations

Nanotechnology is the control, manipulation, and application of matter on an atomic and molecular level. The technology is complex and confusing to consumers, and its long-term safety and effect on the human body, as well as the environment, are unknown. However, for the past decade, nanotechnology has been used to develop consumer products and food with novel and attractive attributes.

Since nanotechnology is still not well known, it is not legitimized; that is, it has not been deemed safe and accepted by society. However, the market for nanotechnology is in the legitimation process. It will take an entire network of …

Synthesis Of Platinum And Platinum-Copper Branched Nanoparticles For Electrooxidation Of Methanol, Eric Courtland Taylor

Graduate Theses and Dissertations

Platinum and Pt alloys are among the most important heterogeneous catalysts for many organic reactions and electrochemical reactions associated with the fuel cell technologies. How to reduce Pt usage while maintaining the performance of the catalysts becomes a subject for intensive research in materials chemistry. For heterogeneous catalysis, the catalytic reactivity and selectivity are strongly correlated with different crystallographic facets exposed on the surface. The facets with high-index planes whose Miller indices with at one is larger than unity are generally more active than those with low-index planes (e.g., {100}, {111}, and {110}). Tuning the morphology of the nanoparticles to …

Pan Nanofibers And Nanofiber Reinforced Composites, Cheng Ren

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Nanomaterials play an important role in the development of nanotechnology. They possess unique mechanical, physical, and chemical properties coupled with small size and ultrahigh surface area that can provide critical advantages for applications. Continuous nanofibers attract special interest due to their dual nano-macro nature and ability to bridge scales. Nanofibers are being considered for a broad range of applications spanning advanced filters, separation membranes, ultrasensitive sensors, micro/nano actuators, nanoprobes, tissue engineering scaffolds, protective and smart closing, and multifunctional composites. Most of these applications require certain mechanical properties and robustness. However, the literature on the mechanical behavior of nanofibers and their …

Hysteretic Response Of Chemical Vapor Deposition Graphene Field Effect Transistors On Sic Substrates, Edward Cazalas, Isaac Childres, Amanda Majcher, Ting Fung Chung, Yong P. Chen, Igor Jovanovic

Birck and NCN Publications

Graphene field effect transistors (GFETs) fabricated by chemical vapor deposition graphene deposited onto SiC substrates exhibit sensitivity to broadband visible light. The hysteretic nature of this GFET type was studied utilizing a new current-voltage measurement technique in conjunction with current-time measurements. This measurement method accounts for hysteretic changes in graphene response and enables transfer measurements that can be attributed to fixed gate voltages. Graphene hysteresis is shown to be consistent with electrochemical p-type doping, and current-time measurements clearly resolve a hole to electron to hole carrier transition in graphene with a single large change in gate voltage. (C) 2013 AIP …

Surface Morphology Evolution Of M-Plane (1(1)Over-Bar00) Gan During Molecular Beam Epitaxy Growth: Impact Of Ga/N Ratio, Miscut Direction, And Growth Temperature, Jiayi Shao, Liang Tang, Colin Edmunds, Geoff C. Gardner, Oana Malis, Michael J. Manfra

Birck and NCN Publications

We present a systematic study of morphology evolution of [1 (1) over bar 00] m-plane GaN grown by plasma-assisted molecular beam epitaxy on free-standing m-plane substrates with small miscut angles towards the -c [000 (1) over bar] and +c [0001] directions under various gallium to nitrogen (Ga/N) ratios at substrate temperatures T = 720 degrees C and T = 740 degrees C. The miscut direction, Ga/N ratio, and growth temperature are all shown to have a dramatic impact on morphology. The observed dependence on miscut direction supports the notion of strong anisotropy in the gallium adatom diffusion barrier and growth …