Nanoscience and Nanotechnology Commons^™

Experimentally Validated 3d Md Model For Afm-Based Tip-Based Nanomanufacturing, Rapeepan Promyoo

Open Access Dissertations

In order to control AFM-based TBN to produce precise nano-geometry efficiently, there is a need to conduct a more focused study of the effects of different parameters, such as feed, speed, and depth of cut on the process performance and outcome. This is achieved by experimentally validating a MD simulation model of nanomachining, and using it to conduct parametric studies to guide AFM-based TBN. A 3D MD model with a larger domain size was developed and used to gain a unique insight into the nanoindentation and nanoscratching processes such as the effect of tip speed (e.g. effect of tip speed …

Carbon Nanotube Thermal Interfaces And Related Applications, Stephen L. Hodson

Open Access Dissertations

The development of thermal interface materials (TIMs) is necessitated by the temperature drop across interfacing materials arising from macro and microscopic irregularities of their surfaces that constricts heat through small contact regions as well as mismatches in their thermal properties. Similar to other types of TIMs, CNT TIMs alleviate the thermal resistance across the interface by thermally bridging two materials together with cylindrical, high-aspect ratio, and nominally vertical conducting elements. Within the community of TIM engineers, the vision driving the development of CNT TIMs was born from measurements that revealed impressively high thermal conductivities of individual CNTs. This vision was …

Wave Propagation And Imaging In Structured Optical Media, Zun Huang

Open Access Dissertations

Structured optical media, usually characterized by periodic patterns of inhomogeneities in bulk materials, provide a new approach to ultimate control of wave propagation with possible practical applications: from distributed feedback lasers by diffraction gratings, to highly nonlinear performance for super-continuum generation, to fiber-optic telecommunications by microstructured photonic crystal fibers, to invisibility cloaking, to super-resolution imaging with metamaterials etc.

In particular, structured optical media allow to manipulate the wave propagation and dispersion. In this thesis, we focus on engineering the propagation phase dispersion by modulating the compositions and dimensions of the periodic elements. By tailoring the dispersion in momentum space, we …

Towards Building A Prototype Spin-Logic Device, Ashish Verma Penumatcha

Open Access Dissertations

Since the late 1980s, several key discoveries, such as Giant and Tunneling Magne- toresistance, and advances in magnetic materials have paved the way for exponentially higher bit-densities in magnetic storage. In particular, the discovery of Spin-Transfer Torque (STT) has allowed information to be written to individual magnets using spin-currents. This has replaced the more traditional Oersted-field control used in field-MRAMs and allowed further scaling of magnetic-memories. A less obvious con- sequence of STT is that it has made possible a logic-technology based on magnets controlled by spin-polarized currents. Charge-coupled Spin Logic (CSL) is one such device proposal that couples a …

Optical Sub-Diffraction Limited Focusing For Confined Heating And Lithography, Luis M. Traverso

Open Access Dissertations

Electronics and nanotechnology is constantly demanding a decrease in size of fabricated nanoscale features. This decrease in size has become much more difficult recently due to the limited resolution of optical systems that are fundamental to many nanofabrication methods. A lot of effort has been made to fabricate devices smaller than the diffraction limit of light. Creating devices that are capable of confining fields by means of interference patterns of propagating wave modes and surface plasmon, has proven successful to confine light into smaller spot sizes.

Zone plate diffraction lenses generate spots with dimensions very close to the diffraction limit. …

Liquid Metal Particle Popping: Nanoscale To Macroscale, Trevor R. Lear

Open Access Theses

Liquid metal nanoparticles can be used to produce stretchable electronic devices. Understanding the mechanical properties of liquid metal nanoparticles is crucial to optimizing their use in various applications, especially printing of flexible, stretchable electronics. Smaller nanoparticles are desired for high-resolution printing and compatibility with existing scalable manufacturing methods; however, they contain less liquid metal and are more difficult to rupture than larger particles, making them less desirable for post-processing functionality. This study investigates the mechanics of liquid metal particle rupture as a function of particle size. We employ compression of particle films to characterize the composition of the particle core …

Effects Of Fiber Aspect Radio On Mechanical Performances Of Nano-Short-Fiber-Reinforced Rubber Composites, Zhu Dasheng

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Influence Of Imperfections On Carbon Nanotube Properties, Marino Brcic, Marko Canadija, Josip Brnic

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Mechanical Properties Of Stainless Steels With Heterogeneous Nanostructures, Hiromi Miura, Masakazu Kobayashi, Natuko Sugiura, Naoki Yoshinaga

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Wetting And Interfacial Microstructure Of Porous Si3n4/Si3n4 Joint After Silver Metallization, Yanli Zhuang, Tiesong Lin, Shengjin Wang, Peng He, Dusan P. Sekulic, Dechang Jia, Hongmei Wei

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Review On Joining Of Advanced Materials And Dissimilar Materials In Harbin Institute Of Technology, Jun Qu, Yongping Lei, Peng He, Yunlong Chang

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Numerical Simulation Of Heat Transfer In Porous Metals For Cooling Applications, Edgar Avalos Gauna, Yuyuan Zhao

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Fluence Dependent Surface Modification On Tungsten Coatings Using Low Energy Helium Ion Irradiation At Elevated Temperatures, Cheng Ji, Jitendra K. Tripathi, Theodore J. Novakowski, Valeryi Sizyuk, Ahmed Hassanein

The Summer Undergraduate Research Fellowship (SURF) Symposium

Nuclear fusion is the most promising renewable energy source for the near future. It can provide a large amount of energy using a very small amount of fuel, as compared with that of the coal, oil, or nuclear fission. The chain reaction in nuclear fusion produces the energy and fuel, from hydrogen isotopes available in see water. Tungsten (W) is a leading candidate material for the plasma-facing component (PFC) in nuclear fusion reactors such as ITER (international thermonuclear experimental reactor), because of its high melting point, high yield strength, low erosion and low hydrogen isotope retention. Recent studies showed deeply …

Quantum Dot Lab : Incorporation Of Alloys In The Capping Layer Of Multi-Layer Quantum Dot, Unmesha U. Kale, Prasad Sarangapani, Jim Fonseca, Gerhard Klimeck

The Summer Undergraduate Research Fellowship (SURF) Symposium

Quantum dots have enhanced the performance of several optoelectronic devices. Designing and obtaining optimal quantum dot structures requires intensive simulation. Quantum Dot Lab on nanoHUB provides such a simulation platform. The simulation is fully parallelized and depending on the structure, the tool decides the computational resource which is to be used for the simulation. To obtain accurate predictions of quantum dot structures it is essential to provide a variety of simulation parameters to the user. In this research, a user interface was created where the user can simulate alloys by Random distribution and by Virtual Crystal Approximation(VCA) type distribution in …

Temperature Dependent Surface Modification Of Tungsten Exposed To High-Flux Low-Energy Helium Ion Irradiation, Antony Q. Damico, Jitendra K. Tripathi, Theodore J. Novakowski, Gennady Miloshevsky, Ahmed Hassanein

The Summer Undergraduate Research Fellowship (SURF) Symposium

Nuclear fusion is a great potential energy source that can provide a relatively safe and clean limitless supply of energy using hydrogen isotopes as fuel material. ITER (international thermonuclear experimental reactor) is the world first fusion reactor currently being built in France. Tungsten (W) is a prime candidate material as plasma facing component (PFC) due to its excellent mechanical properties, high melting point, and low erosion rate. However, W undergoes a severe surface morphology change when exposed to helium ion (He⁺) bombardment under fusion conditions. It forms nanoscopic fiber-form structures, i.e., fuzz on the surface. Fuzz is brittle …

Modeling Of A Roll-To-Roll Plasma Cvd System For Graphene, Yudong Chen, Majed A. Alrefae, Anurag Kumar, Timothy S. Fisher

The Summer Undergraduate Research Fellowship (SURF) Symposium

Graphene is a 2D carbon material that has extraordinary physical properties relevant to many industrial applications such as electronics, oxidation barrier and biosensors. Roll-to-roll plasma chemical vapor deposition (CVD) has been developed to manufacture graphene at large scale. In a plasma CVD chamber, graphene is grown on a copper foil as it passes through a high-temperature plasma region. The temperatures of the gas and the copper foil play important roles in the growth of graphene. Consequently, there is a need to understand the temperature and gas velocity distributions in the system. The heat generated in the plasma creates a thermal …

Energy Transfer In Cdse Nanoplatelet Superlattices, Kelly Wang, Jordan Snaider, Libai Huang

The Summer Undergraduate Research Fellowship (SURF) Symposium

Two-dimension CdSe semiconductor nanoplatelets (NPLs) exhibit unique, highly desirable optical and electronic properties, such as large absorption crossection and bright emission. Fӧrster resonance energy transfer (FRET) between NPLs is responsible for the utility of these NPLs in fields such as lasing, lighting, solar energy, and sensing. Here we study energy transfer processes in NPL superlattices using photoluminescence (PL) and time resolved PL (TRPL) spectroscopic methods. Information on the effect of thickness of NPL is obtained through correlating PL and TRPL spectra of CdSe superlattices with AFM measurements. PL spectrum showed narrow fluorescence and absorption peaks at room temperature corresponding to …

Effect Of Particle Concentration And Ac Electric Field Strength On Particle Trapping In Rapid Electrokinetic Patterning (Rep), Sixuan Li, Avanish Mishra, Steve Wereley

The Summer Undergraduate Research Fellowship (SURF) Symposium

Rapid Electrokinetic Patterning (REP) is an optoelectric technique for trapping and translating micro- and nanoparticles non-invasively. It uses a combination of laser-induced AC electrothermal flow and particle-electrode interactions in the presence of a uniform AC electric field. The trapping is governed by laser power, electric field strength, AC frequency and dielectric properties of the particle and the medium. A REP trap has an AC frequency, termed critical frequency, above which particles cannot be trapped. It is expected to be dependent on dielectric properties of the particle and the medium. However, we propose that the particle concentration and AC field strength …

Development Of Micro-/Nano-Architectures For Intracellular Sensing Platform, Ryan M. Preston, Dae Seung Wie, Chi Hwan Lee

The Summer Undergraduate Research Fellowship (SURF) Symposium

Currently available nanotechnologies are capable of creating various nanostructures in controlled dimensions such as particles (0D), wires (1D), membranes (2D), and cubes (3D) by exploiting “top-down” or “bottom-up” methods. However, there exist limitations to systematically construct hierarchical nanostructures with geometric complexities. This study is focused on developing a novel nanofabrication strategy that can rationally produce a set of hierarchical nanostructures configured with precisely engineered facets, tip shapes, and tectonic motifs. We aim to identify a collection of optimal materials, array layouts, basic components, and nanofabrication techniques for the production of hierarchical nanostructures by exploiting device-grade semiconducting silicon materials. To accomplish …

Performance Of Tf-Vls Grown Inp Photovoltaic Cells, Junyan Shi, Yubo Sun, Peter Bermel

The Summer Undergraduate Research Fellowship (SURF) Symposium

A grand challenge of photovoltaics (PV) is to find materials offering a promising combination of low costs and high efficiencies. While III-V material-based PV cells have set many world records, often their cost is much greater than other commercial cells. To help address this gap, thin-film vapor-liquid-solid (TF-VLS) grown Indium Phosphide (InP) PV cells have recently been developed, which both eliminate a key source of high costs and offer a direct bandgap of 1.34eV with potential to approach maximum theoretical efficiencies. However, the unanticipated phenomenon of open circuit voltage (V_oc) degradation has prevented TF-VLS grown InP PV cells …

Dislocation Engineering In Novel Nanowire Structures, Christopher Y. Chow, Samuel T. Reeve, Alejandro Strachan

The Summer Undergraduate Research Fellowship (SURF) Symposium

Leveraging defects is a cornerstone of materials science, and has become increasingly important from bulk to nanostructured materials. We use molecular dynamics simulations to explore the limits of defect engineering by harnessing individual dislocations in nanoscale metallic specimens and utilizing their intrinsic behavior for application in mechanical dampening. We study arrow-shaped, single crystal copper nanowires designed to trap and control the dynamics of dislocations under uniaxial loading. We characterize how nanowire cross-section and stacking-fault energy of the material affects the ability to trap partial or full dislocations. Cyclic loading simulations show that the periodic motion of the dislocations leads to …

Assembly Of Nucleic Acid-Based Nanoparticles By Gas-Liquid Segmented Flow Microfluidics, Matthew L. Capek, Ross Verheul, David H. Thompson

The Summer Undergraduate Research Fellowship (SURF) Symposium

The development of novel and efficient mixing methods is important for optimizing the efficiency of many biological and chemical processes. Tuning the physical and performance properties of nucleic acid-based nanoparticles is one such example known to be strongly affected by mixing efficiency. The characteristics of DNA nanoparticles (such as size, polydispersity, ζ-potential, and gel shift) are important to ensure their therapeutic potency, and new methods to optimize these characteristics are of significant importance to achieve the highest efficacy. In the present study, a simple segmented flow microfluidics system has been developed to augment mixing of pDNA/bPEI nanoparticles. This DNA and …

Generalizing The Quantum Dot Lab Towards Arbitrary Shapes And Compositions, Matthew A. Bliss, Prasad Sarangapani, James Fonseca, Gerhard Klimeck

The Summer Undergraduate Research Fellowship (SURF) Symposium

As applications in nanotechnology reach the scale of countable atoms, computer simulation has become a necessity in the understanding of new devices, such as quantum dots. To understand the various optoelectronic properties of these nanoparticles, the Quantum Dot Lab (QDL) has been created and powered by NEMO5 to simulate on multi-scale, multi-physics bases. QDL is easy to use by offering choices of different QD geometries such as shapes and sizes to the users from a predefined menu. The simplicity of use, however, limits the simulation of general QD shapes and compositions. A method to import generic strained crystalline and amorphous …

Nanophotonics For Dark Materials, Filters, And Optical Magnetism, Mengren Man

Open Access Dissertations

Research on nanophotonic structures for three application areas is described, a near perfect optical absorber based on a graphene/dielectric stack, an ultraviolet bandpass filter formed with an aluminum/dielectric stack, and structures exhibiting homogenizable magnetic properties at infrared frequencies. The graphene stack can be treated as a effective, homogenized medium that can be designed to reflect little light and absorb an astoundingly high amount per unit thickness, making it an ideal dark material and providing a new avenue for photonic devices based on two-dimensional materials. Another material stack arrangement with thin layers of metal and insulator forms a multi-cavity filter that …

Efficient Inelastic Scattering In Atomistic Tight Binding, James A. Charles

Open Access Theses

In this thesis, the coherent and incoherent transport simulation capabilities of the multipurpose nanodevice simulation tool NEMO5 are presented and applied on transport in tunneling field-effect transistors (TFET). A gentle introduction is given to the non-equilibrium Green's function theory. The comparison with experimental resistivity data confirms the validity of the electron-phonon scattering models. Common pitfalls of numerical implementations such as current conservation, energy mesh resolution, and recursive Green's function stability and the applicability of common approximations of scattering self-energies are discussed. The impact of phonon-assisted tunneling on the performance of TFETs is exemplified with a concrete Si nanowire device. The …

Laser Direct Written Silicon Nanowires For Electronic And Sensing Applications, Woongsik Nam

Open Access Dissertations

Silicon nanowires are promising building blocks for high-performance electronics and chemical/biological sensing devices due to their ultra-small body and high surface-to-volume ratios. However, the lack of the ability to assemble and position nanowires in a highly controlled manner still remains an obstacle to fully exploiting the substantial potential of nanowires. Here we demonstrate a one-step method to synthesize intrinsic and doped silicon nanowires for device applications. Sub-diffraction limited nanowires as thin as 60 nm are synthesized using laser direct writing in combination with chemical vapor deposition, which has the advantages of in-situ doping, catalyst-free growth, and precise control of position, …

Physical Properties, Evaporation And Combustion Characteristics Of Nanofluid-Type Fuels, Saad Tanvir

Open Access Dissertations

Nanofluids are liquids with stable suspension of nanoparticles. Limited studies in the past have shown that both energetic and catalytic nanoparticles once mixed with traditional liquid fuels can be advantageous in combustion applications, e.g., increased energy density and shortened ignition delay. Contradictions in existing literature, scarcity of experimental data and lack of understanding on how the added nanoparticles affect the physical properties as well as combustion characteristics of the resulting fuel motivated us to launch a detailed experimental and theoretical investigation.

The surface tension of ethanol and n-decane based nanofluid fuels containing suspended nanoparticles were measured using the pendant drop …

Ultra-Thin Boron Nitride Films By Pulsed Laser Deposition: Plasma Diagnostics, Synthesis, And Device Transport, Nicholas Robert Glavin

Open Access Dissertations

This work describes, for the first time, a pulsed laser deposition (PLD) technique for growth of large area, stoichiometric ultra-thin hexagonal and amorphous boron nitride for next generation 2D material electronics. The growth of boron nitride, in this case, is driven by the high kinetic energies and chemical reactivities of the condensing species formed from physical vapor deposition (PVD) processes, which can facilitate growth over large areas and at reduced substrate temperatures. The use of optical emission spectroscopy during plasma growth provides insight into chemistry, kinetic energies, time of flight data, and spatial distributions within a PVD plasma plume ablated …

Nanoscale Phonon Thermal Conductivity Via Molecular Dynamics, Jonathan M. Dunn

Open Access Theses

Molecular dynamics (MD) simulations provide a useful and simple means of calculating the nanoscale thermal properties of materials, which requires special analysis since the thermal properties of materials change when their dimensions reach the nanoscale. In this research, MD is used to investigate the nanoscale phonon thermal transport of materials that are attracting much interest in the areas of materials science and nuclear physics. In order to evaluate two distinct methods of calculating the thermal conductivity of materials using MD, the simulation methods are first applied to Si. Once an understanding of each simulation method is established, they are then …

Tailoring Optical And Plasmon Resonances In Core-Shell And Core-Multishell Nanowires, Sarath Ramadurgam

Open Access Dissertations

Semiconductor nanowires (NWs) are sub-wavelength structures which exhibit strong optical (Mie) resonances in the visible range. In addition to such optical resonances, the localized surface plasmon resonances (LSPR) in metal and semiconductor (or dielectric) based core-shell (CS) and core-multishell (CMS) NWs can be tailored to achieve novel negative-index metamaterials (NIM), extreme absorbers, invisibility cloaks and sensors. Particularly, in this dissertation, the versatility of CS and CMS NWs for the design of negative-index metamaterials in the visible range and, plasmonic light harvesting in ultrathin photocatalyst layers for water splitting are studied.

Utilizing the LSPR in the metal layer and the magnetic …