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2011

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Articles 31 - 55 of 55

Full-Text Articles in Nanoscience and Nanotechnology

Fabrication And Characterization Of Electrospun Cactus Mucilage Nanofibers, Yanay Pais Jan 2011

Fabrication And Characterization Of Electrospun Cactus Mucilage Nanofibers, Yanay Pais

USF Tampa Graduate Theses and Dissertations

This work seeks to fabricate, optimize, and characterize nanofibers of cactus Opuntia ficus-indica mucilage and Poly (vinyl alcohol) (PVA) by electrospinning. Mucilage is a neutral mixture of sugars produced by cactus and PVA is a non-toxic, water-soluble, synthetic polymer, which is widely used as a co-spinning agent for polymers. Mucilage was extracted from the cactus pad and prepared for electrospinning by mixing with acetic acid. Two types of PVA were used differentiating in high and low molecular weights. Concentrations of PVA were varied to find an adequate threshold for fiber formation. Changing the ratio of PVA to cactus mucilage produced …

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Sub-Cooled Pool Boiling Enhancement With Nanofluids, Elliott Charles Rice Jan 2011

Sub-Cooled Pool Boiling Enhancement With Nanofluids, Elliott Charles Rice

USF Tampa Graduate Theses and Dissertations

Phase-change heat transfer is an important process used in many engineering thermal designs. Boiling is an important phase change phenomena as it is a common heat transfer process in many thermal systems. Phase change processes are critical to thermodynamic cycles as most closed loop systems have an evaporator, in which the phase change process occurs. There are many applications/processes in which engineers employ the advantages of boiling heat transfer, as they seek to improve heat transfer performance. Recent research efforts have experimentally shown that nanofluids can have significantly better heat transfer properties than those of the pure base fluids, such …

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Thermophysical Characterization Of Nanofluids Through Molecular Dynamic Simulations, John Shelton Jan 2011

Thermophysical Characterization Of Nanofluids Through Molecular Dynamic Simulations, John Shelton

USF Tampa Graduate Theses and Dissertations

Using equilibrium molecular dynamics simulations, an analysis of the key thermophysical properties critical to heat transfer processes is performed. Replication of thermal conductivity and shear viscosity observations found in experimental investigations were performed using a theoretical nanopthesis-fluid system and a novel colloid-fluid interaction potential to investigate the key nanofluid parameters. Analysis of both the heat current (thermal conductivity) and stress (shear viscosity) autocorrelation functions have suggested that the dominant physical mechanisms for thermal and momentum transport arises from enhancements to the longitudinal and transverse acoustic modes energy transfer brought about by the increased mass ratio of the nanopthesis to the …

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Pamam Dendrimer-Based Therapeutic And Diagnostic Nanodevices, Admira Bosnjakovic Jan 2011

Pamam Dendrimer-Based Therapeutic And Diagnostic Nanodevices, Admira Bosnjakovic

Wayne State University Dissertations

Dendrimers are ideal materials to be used in the emerging field of nanomedicine. Their nanoscale size and high density of functional groups on their peripheries allow them to be used for various biomedical applications. This work exploits dendrimers as drug delivery vehicles and a versatile platform for capturing biomarkers with improved sensitivity and specificity. Hydroxyl terminated poly(amidoamine) dendrimer (PAMAM-OH) was modified with a linker having amine group at the end and conjugated to two drugs, erythromycin (EM) and allopregnanonolne, respectively and evaluated in vitro. Both drugs were provided with a linker having carboxylic group required for conjugation reaction with dendrimer. …

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Enhanced Field Emission From Vertically Oriented Graphene By Thin Solid Film Coatings, Michael Bagge-Hansen Jan 2011

Enhanced Field Emission From Vertically Oriented Graphene By Thin Solid Film Coatings, Michael Bagge-Hansen

Dissertations, Theses, and Masters Projects

Recent progress and a coordinated national research program have brought considerable effort to bear on the synthesis and application of carbon nanostructures for field emission. at the College of William and Mary, we have developed field emission arrays of vertically oriented graphene (carbon nanosheets, CNS) that have demonstrated promising cathode performance, delivering emission current densities up to 2 mA/mm2 and cathode lifetime > 800 hours. The work function ( & phis;) of CNS and other carbonaceous cathode materials has been reported to be &phis;∼4.5-5.1 eV. The application of low work function thin films can achieve several orders of magnitude enhancement of …

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A New Method For The Removal Of Parasitic Capacitances From Sub-100nm Mosfets Using Low-Noise Split Capacitance-Voltage Measurements, Daniel R. Steinke Jan 2011

A New Method For The Removal Of Parasitic Capacitances From Sub-100nm Mosfets Using Low-Noise Split Capacitance-Voltage Measurements, Daniel R. Steinke

Legacy Theses & Dissertations (2009 - 2024)

The physical shape of MOSFETs and the processing involved in their fabrication give rise to parasitic capacitances. These capacitances are typically small compared to the intrinsic channel capacitance of the device, but as MOSFETs scale into the sub-100nm gate length range, the parasitic capacitances become a significant percentage of the overall measured capacitance, resulting in a source of error in the analysis of these devices. The purpose of this work is to describe these parasitic capacitances and their origin in MOSFET structures and to propose a method for their removal for analysis. The experimental devices used for this work are …

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Energy Band Engineering Using Polarization Induced Interface Charges In Mocvd Grown Iii-Nitride Heterojunction Devices, Neeraj Tripathi Jan 2011

Energy Band Engineering Using Polarization Induced Interface Charges In Mocvd Grown Iii-Nitride Heterojunction Devices, Neeraj Tripathi

Legacy Theses & Dissertations (2009 - 2024)

Characteristics of III-nitride based heterojunction devices are greatly influenced by the presence of high density of polarization induced interface charges. Research undertaken in the current doctoral thesis demonstrates the effect of presence of one, three and six sheets of polarization induced charges in three different III-nitride based devices, namely in a photocathode, a high electron mobility transistor (HEMT) and a hyperspectral detector structure. Through a systematic set of experiments and theoretical modeling an in-depth study of the interaction between multiple sheets of polarization induced charges and their impact on energy band profile was undertaken. Various device designs were studied and …

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Graphene-Based Interconnects : Electrical Performance And Reliability, Tianhua Yu Jan 2011

Graphene-Based Interconnects : Electrical Performance And Reliability, Tianhua Yu

Legacy Theses & Dissertations (2009 - 2024)

According to the ITRS Roadmap, on-chip interconnects wire width and current density will reach 22 nm and 5.8×106 A/cm2 in 2020, respectively. The electrical resistivity of Cu increases with scaled critical dimensions due to exacerbated carrier scattering at grain boundaries and interfaces, resulting in signal speed degradation. Electronmigration (EM)-related failure due to intensified current distribution posts extra limits to ultra-scaled systems. Innovative interconnect solutions are needed to tackle performance and scaling challenges.

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Cost-Effective Imprint Template Fabrication For Step And Flash Imprint Lithography, Adam Marc Munder Jan 2011

Cost-Effective Imprint Template Fabrication For Step And Flash Imprint Lithography, Adam Marc Munder

Legacy Theses & Dissertations (2009 - 2024)

The College of Nanoscale Science and Engineering (CNSE) is studying imprint template fabrication with the 100kV Vistec VB300 Gaussian E-Beam writer. The major goal is to develop and advance imprint template fabrication technology using low cost quartz wafers for proof-of-concept demonstrations.

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Investigation Of Titanium Nitride As Catalyst Support Material And Development Of Durable Electrocatalysts For Proton Exchange Membrane Fuel Cells, Bharat Avasarala Jan 2011

Investigation Of Titanium Nitride As Catalyst Support Material And Development Of Durable Electrocatalysts For Proton Exchange Membrane Fuel Cells, Bharat Avasarala

Legacy Theses & Dissertations (2009 - 2024)

The impending energy and climatic crisis makes it imperative for human society to seek non-fossil based alternative sources for our energy needs. Although many alternative energy technologies are currently being developed, fuel cell technology provides energy solutions, which satisfy a wide range of applications. But the current fuel cell technology is far from its target of large scale commercialization mainly because of its high cost and poor durability. Considerable work has been done in reducing the cost but its durability still needs significant improvement. Of the various materials in a PEM fuel cell, the degradation of electrocatalyst affects its durability …

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An Exploration Of Focused Electron Beam-Induced-Deposition At Cryogenic Temperatures, Matthew Bresin Jan 2011

An Exploration Of Focused Electron Beam-Induced-Deposition At Cryogenic Temperatures, Matthew Bresin

Legacy Theses & Dissertations (2009 - 2024)

A modified version of electron beam-induced-deposition (EBID) has been studied, where cryogenic substrates were employed to alter the growth environment. Cryogenic substrates enabled multi-layer condensed phase films, which, upon electron exposure and reheating to room temperature, exhibited several unique surface morphologies not present in traditional EBID deposits. By analyzing the composition and structure of the cryogenic deposits, along with simulation of energy deposition from exposure, a diffusion based growth mechanism has been proposed. To test the validity of the proposed model, several process variables were investigated including electron flux, electron fluence, condensate thickness and precursor type. Using the knowledge garnered …

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The Formation And Distribution Of Hippocampal Synapses On Patterned Neuronal Networks, Natalie Michelle Dowell-Mesfin Jan 2011

The Formation And Distribution Of Hippocampal Synapses On Patterned Neuronal Networks, Natalie Michelle Dowell-Mesfin

Legacy Theses & Dissertations (2009 - 2024)

ABSTRACT

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Development Of High Band Gap Absorber And Buffer Materials For Thin Film Solar Cell Applications, Daniel Dwyer Jan 2011

Development Of High Band Gap Absorber And Buffer Materials For Thin Film Solar Cell Applications, Daniel Dwyer

Legacy Theses & Dissertations (2009 - 2024)

CuInGaSe2 (CIGS) device efficiencies are the highest of the thin film absorber materials (vs. CdTe, α-Si, CuInSe2). However, the band gap of the highest efficiency CIGS cells deviates from the expected ideal value predicted by models. Widening the band gap to the theoretically ideal value is one way to increase cell efficiencies. Widening the band gap can be accomplished in two ways; by finding a solution to the Ga-related defects which limit the open circuit voltage at high Ga ratios, or by utilizing different elemental combinations to form an alternative high band gap photoactive Cu-chalcopyrite (which includes …

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Effects Of Radiation-Induced Carbon Contamination On The Printing Performance Of Extreme Ultraviolet Masks, Yu-Jen Fan Jan 2011

Effects Of Radiation-Induced Carbon Contamination On The Printing Performance Of Extreme Ultraviolet Masks, Yu-Jen Fan

Legacy Theses & Dissertations (2009 - 2024)

This dissertation investigates one of the remaining issues for extreme ultraviolet (EUV) lithography, the effects of radiation induced carbon contamination on the printing performance of patterned EUV masks. The impact of carbon contamination on EUV masks is significant due to the throughput loss and potential effects on imaging performance, and occurs when multilayer surfaces are exposed to EUV radiation with residual carbonaceous species present. Current carbon contamination research is primarily focused on the lifetime of the multilayer surfaces, determined by reflectivity loss and reduced throughput in EUV exposure tools. However, contamination on patterned EUV masks can cause additional effects on …

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Role Of Interface Band Structure On Hot Electron Transport, John J. Garramone Jan 2011

Role Of Interface Band Structure On Hot Electron Transport, John J. Garramone

Legacy Theses & Dissertations (2009 - 2024)

Knowledge of electron transport through materials and interfaces is fundamentally and technologically important. For example, metal interconnects within integrated circuits suffer increasingly from electromigration and signal delay due to an increase in resistance from grain boundary and sidewall scattering since their dimensions are becoming shorter than the electron mean free path. Additionally, all semiconductor based devices require the transport of electrons through materials and interfaces where scattering and parallel momentum conservation are important. In this thesis, the inelastic and elastic scattering of hot electrons are studied in nanometer thick copper, silver and gold films deposited on silicon substrates. Hot electrons …

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Extreme Ultraviolet Photoresists : Film Quantum Yields And Ler Of Thin Film Resists, Craig D. Higgins Jan 2011

Extreme Ultraviolet Photoresists : Film Quantum Yields And Ler Of Thin Film Resists, Craig D. Higgins

Legacy Theses & Dissertations (2009 - 2024)

Extreme ultraviolet (EUV) is the leading candidate for a commercially viable solution for next generation lithography. The development of EUV chemically amplified photoresists and processes are critical to the future lithographic requirements of the microelectronics industry. To meet the necessary requirements for both integrated circuit (IC) specifications and cost, the resolution, line-edge roughness (LER) and sensitivity all need to be reduced. Unfortunately, a fundamental trade-off has been observed between these three crucial elements. We have predicted that the best way to obtain the required resolution, line-edge roughness and sensitivity (RLS) is to create more acid molecules per photon absorbed. This …

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Electron-Phonon Interactions And Quantum Confinement Effects On Optical Transitions In Nanoscale Silicon Films, Vimal Kumar Kamineni Jan 2011

Electron-Phonon Interactions And Quantum Confinement Effects On Optical Transitions In Nanoscale Silicon Films, Vimal Kumar Kamineni

Legacy Theses & Dissertations (2009 - 2024)

Theoretical studies have attributed the temperature dependence of the linear optical response (dielectric function) of bulk semiconductors to electron-phonon interactions and thermal expansion of the lattice. However, the role of phonons in the optical properties of nanoscale structures is often overlooked. This thesis systematically investigates the impact of both carrier confinement and electron-phonon interactions using nanoscale films of silicon in crystalline silicon quantum wells (c-Si QW). Spectroscopic ellipsometry (SE) is a linear optical technique used to of extract the dielectric function and thickness of very thin films. X-ray reflectivity (XRR) was used as the complementary thickness metrology method. The dielectric …

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High-K Gate Stack On Compound Semiconductor Channel Materials For Low Power, High Performance Digital Logic Applications, Rama Kambhampati Jan 2011

High-K Gate Stack On Compound Semiconductor Channel Materials For Low Power, High Performance Digital Logic Applications, Rama Kambhampati

Legacy Theses & Dissertations (2009 - 2024)

Group III-V compound semiconductors such as InGaAs and InGaSb are actively being considered as channel materials for low power, high performance digital logic applications due to superior carrier transport properties such as mobility and saturation velocity. The high density of interface states at high-k dielectric and III-V interface that results in pinning of Fermi level is one of the major challenges that need to be addressed before III-V CMOS becomes a mainstream technology.

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Fluorinated Acid Amplifiers For Extreme Ultraviolet Lithography, Seth Aaron Kruger Jan 2011

Fluorinated Acid Amplifiers For Extreme Ultraviolet Lithography, Seth Aaron Kruger

Legacy Theses & Dissertations (2009 - 2024)

Extreme ultraviolet lithography (EUV) is a promising candidate for next generation lithography. Although EUV has great potential there are still many challenges that must be solved before the technology can be implemented in the high volume manufacturing of semiconductor devices. The lithographic performance of EUV photoresists is one aspect that requires improvement. Particularly, EUV resists need simultaneous improvements in three properties: resolution, line-edge-roughness and sensitivity. The incorporation of acid amplifiers (AAs) in resists is one method to improve all three properties.

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Applying X-Ray Microscopy And Finite Element Modeling (Fem) To Identify The Mechanism Of Stress-Assisted Void Growth In Through Silicon Via (Tsv), Lay Wai Kong Jan 2011

Applying X-Ray Microscopy And Finite Element Modeling (Fem) To Identify The Mechanism Of Stress-Assisted Void Growth In Through Silicon Via (Tsv), Lay Wai Kong

Legacy Theses & Dissertations (2009 - 2024)

Fabricating through-silicon vias (TSVs) is challenging, especially for conformally filled TSVs, often hampered by the seam line and void inside the TSVs. Stress-assisted void growth in TSVs has been studied by finite element stress modeling and X-ray computed tomography (XCT). Because X-ray imaging does not require TSVs to be physically cross-sectioned, the same TSV can be imaged before and after annealing. Using 8 keV laboratory-based XCT, voids formed during copper electroplating are observed in as-deposited samples and void growth is observed at the void location after annealing. We hypothesize that the mechanism generating voids is hydrostatic stress-assisted void growth. Stresses …

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Optimization And Development Of Silicon-Based Semiconductor Devices Using Tcad, Changwoo Lee Jan 2011

Optimization And Development Of Silicon-Based Semiconductor Devices Using Tcad, Changwoo Lee

Legacy Theses & Dissertations (2009 - 2024)

Computer simulation of the electrical and optical properties of semiconductor devices has been became as an essential tool for developing new device as well as for improving existing device. This presentation describes applications of physical device simulation: (1) design optimization of power MOSFET, which is single crystalline based silicon semiconductor device, for cryogenic temperature application and (2) two-dimensional device simulation of amorphous silicon based solar cell to develop novel photovoltaic device with high efficiency.

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Synthesis, Processing And Characterization Of Silicon-Based Templated Nanowires, Jae Ho Lee Jan 2011

Synthesis, Processing And Characterization Of Silicon-Based Templated Nanowires, Jae Ho Lee

Legacy Theses & Dissertations (2009 - 2024)

Semiconductor and metallic nanowires have attracted substantial attention due to their wide variety of applications, ranging from nanoelectronics to energy storage devices. In particular, self-assembled silicon nanowires (SiNWs) may be an attractive alternative to conventionally processed planar silicon since SiNWs can potentially function as both the switch (i.e. transistor) and local interconnect (e.g. metal silicide nanowire) to form an inherently integrated nanoelectronic system. Also, hierarchical (branched) nanowire systems hold potential for catalysts or porous electrode applications for energy applications

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Investigation Of Novel Alumina Nanoabrasive And The Interactions With Basic Chemical Components In Copper Chemical Mechanical Planarization (Cmp) Slurries, Shravanthi Lakshmi Manikonda Jan 2011

Investigation Of Novel Alumina Nanoabrasive And The Interactions With Basic Chemical Components In Copper Chemical Mechanical Planarization (Cmp) Slurries, Shravanthi Lakshmi Manikonda

Legacy Theses & Dissertations (2009 - 2024)

Chemical mechanical planarization (CMP) is an enabling process technology for IC fabrication to maintain global planarity across the wafer to satisfy lithographic depth of focus constraints. It also enables integration of materials that cannot be anisotropically etched, such as Cu. CMP utilizes nanoparticle abrasives in aqueous slurry to aid in planarization.

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Applications Of Raman Spectroscopy For Silicon Stress Characterization In Integrated Circuits, Colin Mcdonough Jan 2011

Applications Of Raman Spectroscopy For Silicon Stress Characterization In Integrated Circuits, Colin Mcdonough

Legacy Theses & Dissertations (2009 - 2024)

The introduction of mechanical stress in Si-based integrated circuits (ICs), whether desired or undesired, is intrinsic to IC fabrication. The origins are diverse and result from the numerous materials, geometries, and processes involved in fabrication. These stresses can lead to such effects as delamination, void formation and migration, and fracture, and can significantly affect device performance. As a result, stress development is a major concern for reliability, process control, and device design. It is necessary to investigate and characterize the origins and levels of the induced stresses. A more complete fundamental understanding of the evolution of stress in ICs and …

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Effects Of Low Energy E-Beam Irradiation On Graphene And Graphene Field Effect Transistors And Raman Metrology Of Graphene On Split Gate Test Structures, Gayathri Rao Jan 2011

Effects Of Low Energy E-Beam Irradiation On Graphene And Graphene Field Effect Transistors And Raman Metrology Of Graphene On Split Gate Test Structures, Gayathri Rao

Legacy Theses & Dissertations (2009 - 2024)

Apart from its compelling performance in conventional nanoelectronic device geometries, graphene is an appropriate candidate to study certain interesting phenomenon (e.g. the Veselago lens effect) predicted on the basis of its linear electron dispersion relation. A key requirement for the observation of such phenomenon in graphene and for its use in conventional field-effect transistor (FET) devices is the need to minimize defects such as consisting of - or resulting from - adsorbates and lattice non-uniformities, and reduce deleterious substrate effects. Consequently the investigation of the origin and interaction of defects in the graphene lattice is essential to improve and tailor …

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