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Full-Text Articles in Engineering

Ruco To Extend The Scalability Of Ultra-Thin Direct Plate Liners, Daniel Verne Greenslit Jan 2013

Ruco To Extend The Scalability Of Ultra-Thin Direct Plate Liners, Daniel Verne Greenslit

Legacy Theses & Dissertations (2009 - 2024)

In traditional semiconductor technology a sputtered copper seed layer is used to improve the adhesion, microstucture, and electromigration characteristics of electrochemically deposited (ECD) copper. The seed layer is deposited on top of a Ta/TaN stack. The Ta layer acts as an adhesion and nucleation layer for the copper seed and the TaN serves as a diffusion barrier for the Cu. As the line widths continue to shrink, scaling each of these layers becomes more difficult. It would be advantageous for the interconnect to be composed of as much copper as possible, transitioning from the traditional liner seed stack to a …


A Novel Fabrication Technique For Three-Dimensional Nanostructures, Ravi Kiran Bonam Jan 2012

A Novel Fabrication Technique For Three-Dimensional Nanostructures, Ravi Kiran Bonam

Legacy Theses & Dissertations (2009 - 2024)

Three dimensional micro- and nano-structures are commonly used in the field of Photonics, Optoelectronics, Sensors and Biological applications. Although numerous physical models are developed, a major challenge has been in their fabrication which is commonly limited to conventional layer-by-layer techniques. In this dissertation, a novel method for fabricating three dimensional structures using Electron Beam Lithography (EBL) will be presented.


Detailed Modeling Of Soot Size Distribution Evolution And Pollutant Formation Inside Aircraft And Diesel Engines, Chowdhury Golam Moniruzzaman Jan 2012

Detailed Modeling Of Soot Size Distribution Evolution And Pollutant Formation Inside Aircraft And Diesel Engines, Chowdhury Golam Moniruzzaman

Legacy Theses & Dissertations (2009 - 2024)

Combustion emission of soot and pollutant gas species contributes to poor regional air quality near emission sources and to climate change. It is important to understand the formation mechanism and time evolution of these pollutants inside the combustion engine, through detailed modeling of combustion chemistry and microphysics as well as comparison with observation. In this thesis, two multi-zone gas parcel combustion engine models, one for aircraft engines and another for diesel engines, have been developed to study soot size distribution evolution and pollutant formation inside the engines as well as emissions. The models take into account size-resolved (sectional) soot aerosol …


The Influence Of Copper Substrate Orientation On Graphene Growth, Zachary Robert Robinson Jan 2012

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 …


(In, Al) Co-Doped Zinc Oxide As A Novel Material System For Quantum-Well Multilayer Thermoelectrics, Sean C. Teehan Jan 2012

(In, Al) Co-Doped Zinc Oxide As A Novel Material System For Quantum-Well Multilayer Thermoelectrics, Sean C. Teehan

Legacy Theses & Dissertations (2009 - 2024)

Waste heat recovery from low efficiency industrial processes requires high performance thermoelectric materials to meet challenging requirements. The efficiency such a device is quantified by the dimensionless figure of merit ZT=S2σT/қ, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature and қ is the thermal conductivity. For practical applications these devices are only cost-effective if the ZT is higher than 2.


Experimental And Theoretical Analysis Of Strain Engineered Aluminium Nitride On Silicon For High Quality Aluminium(X)Indium(Y)Gallium(1-X-Y)Nitride Epitaxy, Mihir Hemant Tungare Jan 2012

Experimental And Theoretical Analysis Of Strain Engineered Aluminium Nitride On Silicon For High Quality Aluminium(X)Indium(Y)Gallium(1-X-Y)Nitride Epitaxy, Mihir Hemant Tungare

Legacy Theses & Dissertations (2009 - 2024)

III-Nitrides on Si are of great technological importance due to the availability of large area, epi ready Si substrates and the ability to heterointegrate with mature silicon micro and nanoelectronics. The major roadblock with realizing this is the large difference in thermal expansion coefficients and lattice constants between the two material systems. A novel technique developed in our research lab shows the potential of simultaneous and substantial reduction in dislocation and crack density in GaN on Si (111). Research undertaken in the current doctoral dissertation, validates the superior GaN quality on Si obtained using our technique and determines the factors …


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 …


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 …


Nucleation, Wetting And Agglomeration Of Copper And Copper-Alloy Thin Films On Metal Liner Surfaces, Stephanie Florence Labarbera Jan 2011

Nucleation, Wetting And Agglomeration Of Copper And Copper-Alloy Thin Films On Metal Liner Surfaces, Stephanie Florence Labarbera

Legacy Theses & Dissertations (2009 - 2024)

One of the key challenges in fabricating narrower and higher aspect ratio interconnects using damascene technology has been achieving an ultra-thin (~2 nm) and continuous Cu seed coverage on trench sidewalls. The thin seed is prone to agglomeration because of poor Cu wetting on the Ta liner. Using in-situ conductance measurements, the effect of lowering the substrate temperature during Cu seed deposition has been studied on tantalum (Ta) and ruthenium (Ru) liner surfaces. On a Ta surface, it was found that lowering the deposition temperature to -65°C increases the nucleation rate of the Cu thin film, and reduces the minimum …


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.


Investigation Of The Threshold Voltage Shift Effect Of La2o3 On Tin/Hfo2/La2o3/Sio2/Si Stacks, Ming Di Jan 2010

Investigation Of The Threshold Voltage Shift Effect Of La2o3 On Tin/Hfo2/La2o3/Sio2/Si Stacks, Ming Di

Legacy Theses & Dissertations (2009 - 2024)

The semiconductor industry continues to scale (shrink) transistor dimensions to both increase the number of transistors per integrated circuit and their speed. One important aspect of scaling is the need to decrease the equivalent oxide thickness of the transistor gate dielectric while minimizing leakage current. Traditional thin layer SiO2 or SiOxNy films have been replaced by higher dielectric constant film stacks Here we study one example, the HfO2/La2O3/SiO2 stack. This dissertation describes an investigation of the use of La2O3 to reduce the threshold voltage of TiN/HfO2/SiO2/Si stacks (high-k/metal gate stacks). A significant aspect of this study is the determination of …


Design And Development Of Highly Active, Nanoengineered, Platinum Based Core-Shell Electrodes For Proton Exchange Membrane Fuel Cells, Seth Louis Knupp Jan 2010

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.


Quantum Dot Quantum Computation In Iii-V Type Semiconductor, Sanjay K. Prabhakar Jan 2010

Quantum Dot Quantum Computation In Iii-V Type Semiconductor, Sanjay K. Prabhakar

Legacy Theses & Dissertations (2009 - 2024)

Among recent proposals for next-generation, non-charge-based logic is the notion that a single electron can be trapped and spin of the electron can be manipulated through the application of gate potentials. In the thesis, there are two major contributions of the manipulation of electron spin. In regard to the first contribution, we present numerical simulations of such a spin in single electron devices for realistic asymmetric potentials in electrostatically confined quantum dot. Using analytical and numerical techniques we show that breaking in-plane rotational symmetry of the confining potential by applied gate voltage leads to a significant effect on the tuning …


Electron Beam Lithography Throughput And Resolution Enhancement With Innovative Blanker Design, Junru Ruan Jan 2010

Electron Beam Lithography Throughput And Resolution Enhancement With Innovative Blanker Design, Junru Ruan

Legacy Theses & Dissertations (2009 - 2024)

Electron Beam Lithography (EBL) is one of the most important and most widely used methods for nano-fabrication. The primary advantage of electron beam lithography is its high resolution, and its ability to expose nanometer features without a mask. On the other hand, one of the key limitations of electron beam lithography is throughput. Slow blanking speed is one of the major bottlenecks for the system speed. In this dissertation, I will first review the prior literature of high speed blanking. Thorough theoretical and experimental studies are done on the existing designs. Physical models are built and analytical ray tracing is …


Application And Extension Of Glauber Ising-Spin Dynamics In The Context Of A Single Chain Magnet System, Ryan Tucker Kristensen Jan 2009

Application And Extension Of Glauber Ising-Spin Dynamics In The Context Of A Single Chain Magnet System, Ryan Tucker Kristensen

Legacy Theses & Dissertations (2009 - 2024)

The Glauber Ising-spin dynamic with a local equilibrium approximation is applied to infinite and finite one-dimensional (anti-)ferromagnetic Ising chains with classic nearest neighbor interactions. The application of the Glauber dynamic and local equilibrium approximation is then extended to the one-dimensional ferrimagnetic chain with nearest neighbor interactions. Time dependant behavior and equilibrium states of the one-dimensional ferrimagnetic chain are then discussed in terms of the single chain magnet referred to as CoPhOMe, whose behavior empirical data to date suggest is consistent with a one-dimensional Ising ferrimagnet.


Nanocomposite Thin Films Of Au Nanoparticles Embedded In Yttria-Stabilized Zirconia For Plasmonic-Based Harsh Environment Gas Detection, Phillip Henry Rogers Jan 2009

Nanocomposite Thin Films Of Au Nanoparticles Embedded In Yttria-Stabilized Zirconia For Plasmonic-Based Harsh Environment Gas Detection, Phillip Henry Rogers

Legacy Theses & Dissertations (2009 - 2024)

Increased health concerns due to the emission of gases linked to the production of tropospheric ozone by petroleum based fuel burning engines has resulted in the codification of more stringent emissions regulations domestically. Emissions regulations on commercial jetliners are one of the areas to be met with stricter standards. Currently there is not a sensing technology that can detect the emissions gases in the exhaust stream of a jet turbine engine with lower detection limits that meet these standards.