Nanoscience and Nanotechnology Commons^™

Optical Properties Of Nanostructured Dielectric Coatings, Brandon Giatti

Dissertations and Theses

Solar cells have extrinsic losses from a variety of sources which can be minimized by optimization of the design and fabrication processes. Reflection from the front surface is one such loss mechanism and has been managed in the past with the usage of planar antireflection coatings. While effective, these coatings are each limited to a single wavelength of light and do not account for varying incident angles of the incoming light source. Three-dimensional nanostructures have shown the ability to inhibit reflection for differing wavelengths and angles of incidence. Nanocones were modeled and show a broadband, multi-angled reflectance decrease due to …

Transport Properties Of Nano-Silica Contained Self-Consolidating Concrete, Borhan Moradi

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this research study, transport properties of various self-consolidating concretes (SCCs) containing nano-particles (SiO2) were investigated. Nano-silica replaced a portion of the cementitious materials at different replacement levels ranging from 1.5 to 7.5% by weight. For the purpose of this investigation, flow, bulk, and transport properties of SCCs were studied. The investigated transport properties were absorption, water penetration, rapid chloride permeability, capillary absorption, rapid migration, and chloride diffusion. Transport properties of nano-silica SCCs were also compared to those of equivalent silica fume (micro silica) contained concretes, as well as those of control mixture (concrete without nano or micro silica).

Test …

Fundamental Studies Of Supported Graphene Interfaces : Defect Density Of States In Graphene Field Effect Transistors (Fets) And Ideal Graphene - Silicon Schottky Diodes, Dhiraj Sinha

Legacy Theses & Dissertations (2009 - 2024)

The physics of transport in atomically thin 2D materials is an active area of research, important for understanding fundamental properties of reduced dimensional materials and for applications. New phenomena based on graphene may include properties of topologically protected insulators. Applications of these materials are envisioned in electronics, optoelectronics and spintronics.

Investigating Quantum Oscillations In The Thermal Coefficient Of Resistivity Of Ultra-Thin Ag Capping Layers On Cu For Ic Interconnect Applications, Elroy Tatem

Legacy Theses & Dissertations (2009 - 2024)

As the semiconductor industry continues to scale feature sizes, scattering from phonons, surfaces, and grain boundaries result in an increase of metal interconnect resistivity in state-of-the-art integrated circuits (ICs). The interconnect chapter of the 2011 International Technology Roadmap for Semiconductors (ITRS) stated that there are currently no manufacturable solutions in the near term for suitable Cu replacements. Previous studies of thin Ag films deposited on Cu demonstrated oscillations in the electron-phonon interactions within the bilayer system. This thesis investigates oscillations in the resistive properties of the Ag/Cu bilayer system and discusses the applicability of these oscillations to the resistivity challenges …

Nanostructured Tiox As A Catalyst Support Material For Proton Exchange Membrane Fuel Cells, Richard Phillips

Legacy Theses & Dissertations (2009 - 2024)

Recent interest in the development of new catalyst support materials for proton exchange membrane fuel cells (PEMFCs) has stimulated research into the viability of TiO₂-based support structures. Specifically, substoichiometric TiO₂ (TiO_x) has been reported to exhibit a combination of high conductivity, stability, and corrosion resistance. These properties make TiO_x-based support materials a promising prospect when considering the inferior corrosion resistance of traditional carbon-based supports. This document presents an investigation into the formation of conductive and stable TiO_x thin films employing atomic layer deposition (ALD) and a post deposition oxygen reducing anneal (PDORA). …

Metrology Of Epitaxial Thin Films And Periodic Nanostructures Using High Resolution X-Ray Diffraction Techniques, Manasa Medikonda

Legacy Theses & Dissertations (2009 - 2024)

The continued scaling of device size to achieve higher performance and/or lower power operation at lower cost is driving research and development into new, 3D transistor structures such as the FinFET. This research and development effort is highlighting the need for new, advanced measurement capability that is highly accurate, reliable, rapid, and nondestructive. Periodic arrays of fin structures enable process monitoring at each level of fabrication and the maintenance of overall device yield. High resolution x-ray diffraction (HR XRD) has been shown to provide unique capability of characterizing blanket thin films and structural parameters of periodic arrays of fins fabricated …

First-Principles Study Of The Electric Field Effect On The Water-Adsorbed Rutile Titanium Dioxide Surface, Abraham L. Hmiel

Legacy Theses & Dissertations (2009 - 2024)

TiO₂ is a semiconducting material that has been used extensively in many industrial applications, and recently has become a candidate for photocatalytic water splitting, fuel cell anode support materials, sensors, and other novel nanodevices. The interface of TiO2 with water, historically well-studied but still poorly understood, presents a ubiquitous environmental challenge towards the ultimate practical usefulness of these technologies. Ground-state density functional theory (DFT) calculations studying the characteristics of molecular adsorption on model surfaces have been studied for decades, showing constant improvement in the description of the energetics and electronic structure at interfaces. These simulations are invaluable in the …

Growth And Characterization Of Graphene On Cuni Substrates, Parul Tyagi

Legacy Theses & Dissertations (2009 - 2024)

Graphene is a single layer of sp2 bonded carbon atoms that crystallizes in the honeycomb structure. Because of its true two-dimensional structure, it has very unique electrical properties, including a very high carrier mobility that is symmetric for holes and electrons. To realize these unique properties, it is important to develop a method for growing graphene films with uniform thickness and low defect density. One of the most popular methods of growth is by chemical vapor deposition on Cu substrates, because it is self-limited. However many applications require the growth of graphene films that are more than one atomic layer …

Radiation Effects In Gate-All-Around Silicon Nanowire Mosfets And Carbon Nanotube P-N Diodes, Everett Steven Comfort

Legacy Theses & Dissertations (2009 - 2024)

The scaling of MOSFETs has resulted in short channel effects that increase their power consumption above acceptable levels. In order to lower the power dissipation, new device designs and materials are being considered. For example, multiple-gate MOSFETs, including the gate-all-around silicon nanowire (GAA SiNW) MOSFET, are known to reduce short channel effects. Furthermore, new high-mobility channel materials such as single-walled carbon nanotubes (SWNTs) can be integrated to allow for further scaling of the supply voltage, again aiding in lowering power dissipation.

Exposure Assessment And Risk Management Of Engineered Nanoparticles : Investigation In Semiconductor Wafer Processing, Michele Shepard

Legacy Theses & Dissertations (2009 - 2024)

Engineered nanomaterials (ENMs) are currently used in hundreds of commercial products and industrial processes, with more applications being investigated. Nanomaterials have unique properties that differ from bulk materials. While these properties may enable technological advancements, the potential risks of ENMs to people and the environment are not yet fully understood. Certain low solubility nanoparticles are more toxic than their bulk material, such that existing occupational exposure limits may not be sufficiently protective for workers. Risk assessments are currently challenging due to gaps in data on the numerous emerging materials and applications as well as method uncertainties and limitations.

Biomacromolecule Conjugated Nanofiber Scaffold For Salivary Gland Tissue Engineering, Kavitha Jayarathanam

Legacy Theses & Dissertations (2009 - 2024)

ABSTRACT :

Assessing Different Zeolitic Adsorbents For Their Potential Use In Kr And Xe Separation, Breetha Alagappan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Separation of Kr from Xe is an important problem in spent nuclear fuel fission gas management. The energy intensive and expensive cryogenic distillation method is currently used to separate these gases. In this thesis, we have carried out the research into appropriate sorbents for the separation of Kr and Xe using pressure swing adsorption. We have examined zeolites using gas adsorption studies as they have the potential to be more cost effective than other sorbents. Zeolites are microporous aluminosilicates and have ordered pore structures. The pores in zeolites have extra-framework cations are substantially free to move. The mobility of cations …

Understanding Defect Interactions In Si Ultra-Shallow P-N Junctions Formed By Very Low Energy Boron Implantation, Lakshmanan H. Vanamurthy

Legacy Theses & Dissertations (2009 - 2024)

One of the biggest challenges in the scaling of CMOS devices is the formation of a highly activated, abrupt, defect free Source drain extension (SDE) region. This is especially difficult with p-FET's because of the (1) Boron diffusion co-efficient enhancement from Transient enhanced diffusion (TED) and (2) low solid solubility of

Modified Statistical Dynamical Diffraction Theory : A Novel Metrological Analysis Method For Partially Relaxed And Defective C Doped Si And Sige Heterostructures, Paul Kenneth Shreeman

Legacy Theses & Dissertations (2009 - 2024)

The statistical dynamical diffraction theory, which has been initially developed by late Kato remained in obscurity for many years due to intense and difficult mathematical treatment that proved to be quite challenging to implement and apply. With assistance of many authors in past (including Bushuev, Pavlov, Pungeov, and among the others), it became possible to implement this unique x-ray diffraction theory that combines the kinematical (ideally imperfect) and dynamical (the characteristically perfect diffraction) into a single system of equations controlled by two factors determined by long range order and correlation function within the structure. The first stage is completed by …

Graphene-Based Post-Cmos Architecture, Sansiri Tanachutiwat

Legacy Theses & Dissertations (2009 - 2024)

The semiconductor industry relies on CMOS technology which is nearing its scaling limitations. In order to continue the historical growth rate of the device density of digital logic chips, novel nanomaterials and nanodevices will need to be developed.

Measurement Of Electron Spin Transport In Graphene On 6h-Silicon Carbide(0001), Joseph Abel

Legacy Theses & Dissertations (2009 - 2024)

The focus of this thesis is to demonstrate the potential of wafer scale graphene spintronics. Graphene is a single atomic layer of sp2-bonded carbon atoms that has high carrier mobilities, making it a desirable material for future nanoscale electronic devices. The vision of spintronics is to utilize the spin of the electron to produce novel high-speed low power consuming devices. Materials with long spin relaxation times and spin diffusion lengths are needed to realize these goals. Graphene is an ideal material as it meets these requirements and is amenable to planar device geometries.

The Influence Of Copper Substrate Orientation On Graphene Growth, Zachary Robert Robinson

Legacy Theses & Dissertations (2009 - 2024)

This dissertation is focused on determining the influence of the copper substrate on graphene grown by \ac{CVD}. Graphene, which can be grown in single atomic layers on copper substrates, has potential applications in future electronic devices. One of the key issues for the use of graphene grown by chemical vapor deposition for device applications is the influence of defects on the transport properties of the graphene. For instance, growth on metal foil substrates results in multi-domain graphene growth because the foil substrates themselves have a variety of different surface terminations. Therefore, they don't serve as a very good template for …

Ionic Current Rectification Phenomena In Asymmetrical Polymer Nanopores Under Salt Gradients, Murat Bakirci

Mechanical & Aerospace Engineering Theses & Dissertations

The magnitude of current through a conical nanopore filled with an electrolyte solution depends on the polarity of the applied bias, indicating an asymmetric diode-like current-voltage (I-V) curve. This kind of phenomenon refers to ionic current rectification (ICR), which is of interest because many ion-channel proteins in cellular membranes are rectifying. In addition, ICR in nanopores can be used to control ion concentrations in nano- and microfluidic systems. In this study, the ICR phenomenon through a conical nanopore simultaneously subjected to an electric field and salt concentration gradient is experimentally and numerically investigated.

The experiments were conducted in an Izon's …

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 …

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.

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 …

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 …

A Study Of Reticle Non-Flatness Induced Image Placement Error In Extreme Ultraviolet Lithography, Sudharshanan Raghunathan

Legacy Theses & Dissertations (2009 - 2024)

As the semiconductor industry continues scaling devices to smaller sizes, the need for next generation lithography technology for fabricating these small structures has always been at the forefront. Over the past few years, conventional optical lithography technology which has adopted a series of resolution enhancement techniques to support the scaling needs is expected to run out of steam in the near future. Extreme Ultra Violet lithography (EUVL) is being actively pursued by the semiconductor industry as one of the most promising next generation lithographic technologies. Most of the issues unique to EUVL arise from the use of 13.5 nm light …

Fabrication And Characterization Of Nanomaterials Grown By Electron Beam Induced Deposition Process, Juntao Li

Legacy Theses & Dissertations (2009 - 2024)

Platinum&ndash and tungsten&ndashcontaining materials were grown on bulk substrates from a variety of precursors including (CH₃)₃CH₃C₅H₄Pt, W(CO)₆, WF₆, and Pt(PF₃)₄ in either a high vacuum dual beam focused ion beam/scanning electron microscope (FIB&ndashSEM) or an environmental scanning electron microscope (ESEM). The effects of deposition conditions on the growth kinetics, microstructure and composition of the grown materials, structural and chemical homogeneity of impurities inside the deposits as well as the resistivity were investigated.

Design And Development Of Highly Active, Nanoengineered, Platinum Based Core-Shell Electrodes For Proton Exchange Membrane Fuel Cells, Seth Louis Knupp

Legacy Theses & Dissertations (2009 - 2024)

Highly active nanoengineered core-shell electrocatalyst have a great potential to be used as fuel cell electrodes. They can alleviate problems related with commercial carbon supported platinum by simultaneously lowering cost while enhancing reaction kinetics and overall performance. More recently, use of nanoengineered core-shell electrode structures have showed their ability to enhance the stability and overall lifetime of the catalyst without sacrificing the electrode's performance. We studied the potential of using highly active core-shell nanoparticles supported on carbon nanomaterials as fuel cell electrodes.

Morphological, Structural, And Optical Studies Of Undoped And Doped-Zno Nanostructure., Ramin Yousefi

Student Works (2010-2019)

Research concerning one-dimensional nanomaterials has grown tremendously ever since carbon nanotubes were discovered by Iijima (1991), silicon nanowires were grown by Lieber's group (1998), and ZnO nanowires and nanobelts were found by Wang's group from Georgia Tech (Pan et al., 2001). Such researches on one-dimensional structures have been one of the most important branches of science during recent decades. We can now observe the impact of these studies on the technology of one-dimensional materials and also the advanced prospect of developing new technologies. Based on this motivation, this thesis attempts to investigate some unknown properties of ZnO nanostructures as …

Giant Raman Enhancement On Nanoporous Gold Film By Conjugating With Nanoparticles For Single-Molecule Detection, Lihua Qian, Biswajit Das, Yan Li, Zhilin Yang

Electrical & Computer Engineering Faculty Research

Hot spots have the contradictively geometrical requirements for both the narrowest interstices to provide strong near-field coupling, and sufficient space to allow entrance of the analytes. Herein, a two-step method is employed to create hot spots within hybrid nanostructures, which consist of self-supported nanoporous gold films with the absorbed probes and subsequent nanoparticle conjugates without surface agents or mechanical motion. The molecules confined into 1 nm interstice exhibit 2.9 × 10⁷ times enhancement in Raman scattering compared to pure nanoporous gold. Giant enhancement primarily results from strong near-field coupling between nanopore and nanoparticle, which is theoretically confirmed by finite-difference …

A Systematic Study Of Atomic Layer Deposition Of Platinum Nano-Scale Metallization Films And Their Application To Electrical Contacts In Porous Alumina Templates, Ngoc H. Tran

Electrical & Computer Engineering Theses & Dissertations

ln this thesis a comprehensive analysis is presented on nano-scale thin films of platinum deposited with Angstrom resolution by Atomic Layer Deposition (ALD) technology utilizing the Cambridge Nanotech Savannah 100 ALD system. Physical characterizations of film thickness, film morphology, and surface roughness of the deposited platinum were all performed before and after rapid thermal annealing (RTA) and as a function of forming gas annealing (FGA). Noble metal thin films of platinum were deposited on four inch wafers of p-type boron doped &100& oriented silicon (Si) substrates. The ALD film thickness was measured with a novel method utilizing the linear dependence …

A Study Of Cantilever-Free Instrumentation For Nanoscale Magnetic Measurements, Bruce Adair Altemus

Legacy Theses & Dissertations (2009 - 2024)

The evolution of the Atomic Force Microscope (AFM) into the Magnetic Force Microscope (MFM) and Magnetic Resonance Force Microscope (MRFM) has had a substantial impact on the characterization of nanoscale phenomena. Detection of 10-17 Newtons per root Hertz has occurred with use of an ultra-sensitive cantilever along with optical interferometry methods within these geometries. The sensitivity of these platforms is dependent on the characteristics of the cantilever, where increased length and a low Young's modulus increase the force sensitivity (meters/Newtons). Using IC fabrication techniques, the realization of generating cantilevers with this sensitivity is feasible, but stress compensation layers are required …

A Study Of Cantilever-Free Instrumentation For Nanoscale Magnetic Measurements, Bruce Adair Altemus

Legacy Theses & Dissertations (2009 - 2024)

The evolution of the Atomic Force Microscope (AFM) into the Magnetic Force Microscope (MFM) and Magnetic Resonance Force Microscope (MRFM) has had a substantial impact on the characterization of nanoscale phenomena. Detection of 10-17 Newtons per root Hertz has occurred with use of an ultra-sensitive cantilever along with optical interferometry methods within these geometries. The sensitivity of these platforms is dependent on the characteristics of the cantilever, where increased length and a low Young's modulus increase the force sensitivity (meters/Newtons). Using IC fabrication techniques, the realization of generating cantilevers with this sensitivity is feasible, but stress compensation layers are required …