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Full-Text Articles in Nanoscience and Nanotechnology

Deconvolving The Steps To Control Morphology, Composition, And Structure, In The Synthesis Of High-Aspect-Ratio Metal Oxide Nanomaterials, Lei Yu Jan 2017

Deconvolving The Steps To Control Morphology, Composition, And Structure, In The Synthesis Of High-Aspect-Ratio Metal Oxide Nanomaterials, Lei Yu

Theses and Dissertations--Chemistry

Metal oxides are of interest not only because of their huge abundance but also for their many applications such as for electrocatalysts, gas sensors, diodes, solar cells and lithium ion batteries (LIBs). Nano-sized metal oxides are especially desirable since they have larger surface-to-volume ratios advantageous for catalytic properties, and can display size and shape confinement properties such as magnetism. Thus, it is very important to explore the synthetic methods for these materials. It is essential, therefore, to understand the reaction mechanisms to create these materials, both on the nanoscale, and in real-time, to have design control of materials with desired ...


Laser Direct Written Silicon Nanowires For Electronic And Sensing Applications, Woongsik Nam Aug 2016

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 ...


Frequency Multiplication In Silicon Nanowires, Marius Mugurel Ghita Jul 2016

Frequency Multiplication In Silicon Nanowires, Marius Mugurel Ghita

Dissertations and Theses

Frequency multiplication is an effect that arises in electronic components that exhibit a non-linear response to electromagnetic stimuli. Barriers to achieving very high frequency response from electronic devices are the device capacitance and other parasitic effects such as resistances that arise from the device geometry and are in general a function of the size of the device. In general, smaller device geometries and features lead to a faster response to electromagnetic stimuli. It was posited that the small size of the silicon nanowires (SiNWs) would lead to small device capacitance and spreading resistance, thus making the silicon nanowires useful in ...


Doped Tio2 Nanowires For Applications In Dye Sensitized Solar Cells And Sacrifical Hydrogen Production, Qasem Alsharari Apr 2016

Doped Tio2 Nanowires For Applications In Dye Sensitized Solar Cells And Sacrifical Hydrogen Production, Qasem Alsharari

Electronic Thesis and Dissertation Repository

This thesis explores the synthesis of metal oxide 1-D nanowires using a sol-gel method in supercritical carbon dioxide (sc-CO2), as an environmental friendly enabling solvent. Porous nanowires were synthesized and their performance was tested in dye sensitized solar cell and sacrifical hydrogen production. Titanium isopropoxide (TIP) was used as a precursor for titania synthesis while copper, bismuth and indium were examined as dopants, respectively. The sol-gel reactions were catalyzed by acetic acid in CO2 at a temperature of 60 °C and pressure of 5000 psi. It was observed that acetic acid/monomer ratio > 4 produced nanowires while a ...


Tailoring Optical And Plasmon Resonances In Core-Shell And Core-Multishell Nanowires, Sarath Ramadurgam Jan 2016

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 ...


Magnetic And Optical Holonomic Manipulation Of Colloids, Structures And Topological Defects In Liquid Crystals For Characterization Of Mesoscale Self-Assembly And Dynamics, Michael Christopher Mason Varney Jan 2014

Magnetic And Optical Holonomic Manipulation Of Colloids, Structures And Topological Defects In Liquid Crystals For Characterization Of Mesoscale Self-Assembly And Dynamics, Michael Christopher Mason Varney

Physics Graduate Theses & Dissertations

Colloidal systems find important applications ranging from fabrication of photonic crystals to direct probing of phenomena encountered in atomic crystals and glasses; topics of great interest for physicists exploring a broad range of scientific, industrial and biomedical fields. The ability to accurately control particles of mesoscale size in various liquid host media is usually accomplished through optical trapping methods, which suffer limitations intrinsic to trap laser intensity and force generation. Other limitations are due to colloid properties, such as optical absorptivity, and host properties, such as viscosity, opacity and structure. Therefore, alternative and/or novel methods of colloidal manipulation are ...


Development Of Nanostructured Limpo4 (M=Fe, Mn) As Cathodes For High Performance Lithium-Ion Batteries, Jinli Yang Sep 2013

Development Of Nanostructured Limpo4 (M=Fe, Mn) As Cathodes For High Performance Lithium-Ion Batteries, Jinli Yang

Electronic Thesis and Dissertation Repository

Olivine LiFePO4 has garnered the most interest because of its environmental benignity, high safety and theoretical capacity. However, the major limitation for LiFePO4 is the intrinsically poor electronic conductivity and ionic conductivity. The sluggish kinetics for LiFePO4 could be overcome by reducing the size, coating with conductive carbon, or doping with isovalent ions. The decrease of the size to nanoscale could shorten the diffusion time of Li ions in LiFePO4 during intercalation/deintercalation process, but the nano-size active material usually accompanies with low tap density. Carbon coating and carbon addition could alleviate the poor electronic conductivity ...


Nanowire Giant Magnetoresistance Thin Films For Magnetic Sensors, Bryan Cox Jul 2012

Nanowire Giant Magnetoresistance Thin Films For Magnetic Sensors, Bryan Cox

Doctoral Dissertations

This dissertation details a novel method to fabricate magnetic sensors using nanowire giant magnetoresistance (GMR) thin films. In 1988, Albert Fert and Peter Grünberg both independently discovered a new physical phenomenon called GMR. GMR is a quantum mechanical effect found in thin film materials that are composed of alternating nanoscale ferromagnetic and non-magnetic conductive layers. When a GMR material is in the presence of a magnetic field, a change in electrical resistance is observed. The GMR effect has been utilized to produce magnetic sensors that have been used in a variety of applications, such as computer hard drive read heads ...


Semiconductor Nanowires: Optical Properties And All-Optical Switching, Brian Edward Piccione Jan 2012

Semiconductor Nanowires: Optical Properties And All-Optical Switching, Brian Edward Piccione

Publicly Accessible Penn Dissertations

The optical properties of semiconductor nanowires are both important from a fundamental materials physics standpoint and necessary to understand in engineering applications: nanowire photovoltaic devices, sensors, and lasers, among others, could all benefit. Unfortunately, these optical properties are not easy to ascertain. Transmission times are short, in-coupling of white probe light is difficult, and the angle-resolved measurements typically used to determine material dispersion relations in bulk materials are hindered by diffraction effects at subwavelength nanowire end facets.

Here, we present a series of experimental techniques and theoretical models developed to study of the optical properties of active nanowire waveguides. Beginning ...


Growth And Characterization Of Gallium Nitride Nanowire Leds For Application As On-Chip Optical Interconnects, Matt Brubaker Jan 2012

Growth And Characterization Of Gallium Nitride Nanowire Leds For Application As On-Chip Optical Interconnects, Matt Brubaker

Mechanical Engineering Graduate Theses & Dissertations

Gallium nitride (GaN) nanowires have potential as nanoscale optoelectronic building blocks that can be functionally integrated with silicon MEMS and IC devices. This dissertation presents an overview of the synthesis, characterization, and application of GaN nanowire light-emitting-diodes (LEDs) grown by plasma-assisted molecular beam epitaxy (MBE). Specifically, this research demonstrates discrete axial p-n junction nanowires that produce ultra-violet (UV) electroluminescence at ~40 nW optical power. It further demonstrates that a two-nanowire optical interconnect device can be fabricated from axial p-n junction nanowires with light-emitting and photoconductive capabilities. The nanowire structures obtained from MBE growth were found to depend sensitively on the ...


Exploring Bacterial Nanowires: From Properties To Functions And Implications, Kar Man Leung Aug 2011

Exploring Bacterial Nanowires: From Properties To Functions And Implications, Kar Man Leung

Electronic Thesis and Dissertation Repository

The discovery of electrically conductive bacterial nanowires from a broad range of microbes provides completely new insights into microbial physiology. Shewanella oneidensis strain MR-1, a dissimilatory metal-reducing bacterium, produces extracellular bacterial nanowires up to tens of micrometers long, with a lateral dimension of ~10 nm. The Shewanella bacterial nanowires are efficient electrical conductors as revealed by scanning probe techniques such as CP-AFM and STM.

Direct electrical transport measurements along Shewanella nanowires reveal a measured nanowire resistivity on the order of 1 Ω∙cm. With electron transport rates up to 109/s at 100 mV, bacterial nanowires can serve as ...