Engineering Commons^™

Effects Of Forming Gas Anneal On Ultrathin Ingaas Nanowire Metal-Oxide-Semiconductor Field-Effect Transistors, Mengwei Si, Jiangjiang Gu, Xinwei Wang, Jiayi Shao, Xuefei Li, Michael J. Manfra, Roy G. Gordon, Peide D. Ye

Birck and NCN Publications

InGaAs gate-all-around metal-oxide-semiconductor field-effect transistors (MOSFETs) with 6 nm nanowire thickness have been experimentally demonstrated at sub-80 nm channel length. The effects of forming gas anneal (FGA) on the performance of these devices have been systematically studied. The 30min 400 degrees C FGA (4% H-2/96% N-2) is found to improve the quality of the Al2O3/InGaAs interface, resulting in a subthreshold slope reduction over 20mV/dec (from 117mV/dec in average to 93mV/dec). Moreover, the improvement of interface quality also has positive impact on the on-state device performance. A scaling metrics study has been carried out for FGA treated devices with channel lengths …

Laser Direct Writing Of Silicon Field Effect Transistor Sensors, Woongsik Nam, James I. Mitchell, Chookiat Tansarawiput, Minghao Qi, Xianfan Xu

Birck and NCN Publications

We demonstrate a single step technique to fabricate silicon wires for field effect transistor sensors. Boron-doped silicon wires are fabricated using laser direct writing in combination with chemical vapor deposition, which has the advantages of precise control of position, orientation, and length, and in situ doping. The silicon wires can be fabricated to have very rough surfaces by controlling laser operation parameters, and thus, have large surface areas, enabling high sensitivity for sensing. Highly sensitive pH sensing is demonstrated. We expect our method can be expanded to the fabrication of various sensing devices beyond chemical sensors. (C) 2013 American Institute …

Deuterium Uptake In Magnetic-Fusion Devices With Lithium-Conditioned Carbon Walls, P. S. Krstic, Jean Paul Allain, C. N. Taylor, J. Dadras, S. Maeda, K. Morokuma, J. Jakowski, A. Allouche, C. H. Skinner

Birck and NCN Publications

Lithium wall conditioning has lowered hydrogenic recycling and dramatically improved plasma performance in many magnetic-fusion devices. In this Letter, we report quantum-classical atomistic simulations and laboratory experiments that elucidate the roles of lithium and oxygen in the uptake of hydrogen in amorphous carbon. Surprisingly, we show that lithium creates a high oxygen concentration on a carbon surface when bombarded by deuterium. Furthermore, surface oxygen, rather than lithium, plays the key role in trapping hydrogen. DOI: 10.1103/PhysRevLett.110.105001

Thermal Transport In Sige Superlattice Thin Films And Nanowires: Effects Of Specimen And Periodic Lengths, Keng-Hua Lin, Alejandro Strachan

Birck and NCN Publications

We compute the thermal conductivity of superlattice (SL) thin films and nanowires for various SL periods and total specimen lengths using nonequilibrium molecular dynamics. Both types of materials exhibit similar behaviors with respect to SL period but the thermal conductivity of the thin films exhibits a significantly higher sensitivity to the specimen length. Notably, the thermal conductivity of SL thin films is smaller than those of the corresponding nanowires for specimen lengths below approximately 35 nm. These results arise from the complex dependence of the conductivities of the interfaces and the SL components on the specimen size and period. These …

A Computational Study Of The Thermoelectric Performance Of Ultrathin Bi2te3 Films, Jesse Maassen, Mark S. Lundstrom

Birck and NCN Publications

The ballistic thermoelectric performance of ultrathin films of Bi2Te3, ranging in thickness from 1 to 6 quintuple layers, is analyzed using density functional theory combined with the Landauer approach. Our results show that the thinnest film, corresponding to a single quintuple layer, has an intrinsic advantage originating from the particular shape of its valence band, leading to a large power factor and figure-of-merit exceeding bulk Bi2Te3. The interaction between the top and bottom topological surface states is key. The thinnest film yields a six-fold increase in power factor compared to bulk. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4794534]

Limitations Of The High-Low C-V Technique For Mos Interfaces With Large Time Constant Dispersion, Ashish Verma Penumatcha, Steven Swandono, James A. Cooper

Birck and NCN Publications

We discuss the limitations of the high-low CV technique in evaluating the interface trap density (D-TT) in MOS samples with a large time constant dispersion, as occurs in silicon carbide (SiC). We show that the high-low technique can seriously underestimate D-IT for samples with large time constant dispersion, even if elevated temperatures are used to extend the range of validity.

Performance Measures For Local Agency Traffic Signals, Jay Grossman, Darcy M. Bullock

Indiana Local Technical Assistance Program (LTAP) Technical Reports

The project focused on accelerating implementation of research recommendations emerging from traffic signal research projects conducted by the National Cooperative Research Program and Indiana Department of Transportation. This project developed specification language that was subsequently used in procurements in Elkhart County, IN; Lafayette, IN; and Morgantown, WV. The performance measures specified in Appendix A and subsequently deployed in Elkhart County, IN, and Lafayette, IN, were the first commercial deployment of real-time traffic signal performance measures recommended by NCHRP 3-79a. The deployment in Lafayette, IN, received an ACEC award in March 2012. In addition to accelerating implementation, this research project examined …

2013 Directory Of Indiana State, County, City And Town Officials Responsible For Road And Street Work, Indiana Ltap

Indiana Local Technical Assistance Program (LTAP) Directory

Contact information for local agency officials and employees responsible for Indiana’s local road infrastructure.

2012 Statewide Bridge Sufficiency Rating Report, Indiana Ltap, Indiana Department Of Transportation, Indiana Department Of Local Government Finance

Indiana Local Technical Assistance Program (LTAP) Publications

The main purpose of this report is to provide bridge sufficiency rating information for the bridges in each county to county officials as a convenient starting point for formulating a long-range plan to cope with their county bridge deficiencies. This information results from the data generated by the national Bridge Inspection Standards (NBIS) program authorized by the 1968 Federal-Aid Highway Act.

High-Resolution Dynamic Atomic Force Microscopy In Liquids With Different Feedback Architectures, John Melcher, David Martinez-Martin, Miriam Jaafar, Julio Gomez-Herrero, Arvind Raman

Birck and NCN Publications

The recent achievement of atomic resolution with dynamic atomic force microscopy (dAFM) [Fukuma et al., Appl. Phys. Lett. 2005, 87, 034101], where quality factors of the oscillating probe are inherently low, challenges some accepted beliefs concerning sensitivity and resolution in dAFM imaging modes. Through analysis and experiment we study the performance metrics for high-resolution imaging with dAFM in liquid media with amplitude modulation (AM), frequency modulation (FM) and drive-amplitude modulation (DAM) imaging modes. We find that while the quality factors of dAFM probes may deviate by several orders of magnitude between vacuum and liquid media, their sensitivity to tip-sample forces …

Investigations Of Attitudes Towards Offshore Wind Farm Development In Ireland: Their Implication Towards Future Development Of The Industry., Aidan Melia

Purdue Polytechnic Masters Theses

This current research investigates what the attitudes of Irish people are towards the development of offshore wind farms in Ireland. Using a qualitative approach, a questionnaire is carefully designed and distributed among a sample population from three coastal communities. One is located on the west coast and two on the east coast. The two locations on the east coast have an involvement in offshore wind farms. One of the locations plays host to Ireland’s only offshore wind farm, while there are plans in place for an offshore wind farm at the other location. The results from the questionnaires are analyzed …

Cross-Plane Thermal Properties Of Transition Metal Dichalcogenides, C. Muratore, V. Varshney, J. J. Gengler, J. J. Hu, J. E. Bultman, T. M. Smith, P. J. Shamberger, Bo Qiu, Xiulin Ruan, A. K. Roy, A. A. Voevodin

Birck and NCN Publications

In this work, we explore the thermal properties of hexagonal transition metal dichalcogenide compounds with different average atomic masses but equivalent microstructures. Thermal conductivity values of sputtered thin films were compared to bulk crystals. The comparison revealed a > 10 fold reduction in thin film thermal conductivity. Structural analysis of the films revealed a turbostratic structure with domain sizes on the order of 5-10 nm. Estimates of phonon scattering lengths at domain boundaries based on computationally derived group velocities were consistent with the observed film microstructure, and accounted for the reduction in thermal conductivity compared to values for bulk crystals. (C) …

Instrumentation And Axial Load Testing Of Displacement Piles, Adriano V.D. Bica, Monica Prezzi, Hoyoung Seo, Rodrigo Salgado, Daehyeon Kim

Lyles School of Civil Engineering Faculty Publications

Despite the fact that results of many instrumented pile load tests have been reported in the literature, it is difficult to find well-documented instrumentation procedures that can be used when planning a load testing programme. A load test programme designed to investigate various aspects of the design and behaviour of driven steel piles is discussed in the present paper. Although the literature contains information on load testing of instrumented piles driven in either sand or clay, limited information is available regarding their axial load response in transitional soils (soils composed of various amounts of clay, silt and sand). Results are …

Interfacial Thermal Conductance Limit And Thermal Rectification Across Vertical Carbon Nanotube/Graphene Nanoribbon-Silicon Interfaces, Ajit K. Vallabhaneni, Bo Qiu, Jiuning Hu, Yong P. Chen, Ajit K. Roy, Xiulin Ruan

Birck and NCN Publications

Various models were previously used to predict interfacial thermal conductance of vertical carbon nanotube (CNT)-silicon interfaces, but the predicted values were several orders of magnitude off the experimental data. In this work, we show that the CNT filling fraction (the ratio of contact area to the surface area of the substrate) is the key to remedy this discrepancy. Using molecular dynamics, we have identified an upper limit of thermal interface conductance for C-Si interface which is around 1.25GW/m(2)K, corresponding to a 100% filling fraction of carbon nanotube or graphene nanoribbon on substrate. By extrapolating to low filling fraction (similar to …

Unidirectional Spaser In Symmetry-Broken Plasmonic Core-Shell Nanocavity, Xiangeng Meng, Urcan Guler, Alexander V. Kildishev, Koji Fujita, Katsuhisa Tanaka, Vladimir M. Shalaev

Birck and NCN Publications

The spaser, a quantum amplifier of surface plasmons by stimulated emission of radiation, is recognized as a coherent light source capable of confining optical fields at subwavelength scale. The control over the directionality of spasing has not been addressed so far, especially for a single-particle spasing nanocavity where optical feedback is solely provided by a plasmon resonance. In this work we numerically examine an asymmetric spaser - a resonant system comprising a dielectric core capped by a metal semishell. The proposed spaser emits unidirectionally along the axis of the semishell; this directionality depends neither on the incident polarization nor on …

Strong Heavy-To-Light Hole Intersubband Absorption In The Valence Band Of Carbon-Doped Gaas/Alas Superlattices, M. I. Hossain, Z. Ikonic, J. Watson, J. Shao, P. Harrison, Michael J. Manfra, O. Malis

Birck and NCN Publications

We report strong mid-infrared absorption of in-plane polarized light due to heavy-to-light hole intersubband transitions in the valence band of C-doped GaAs quantum wells with AlAs barriers. The transition energies are well reproduced by theoretical calculations including layer inter-diffusion. The inter-diffusion length was estimated to be 8 +/- 2 angstrom, a value that is consistent with electron microscopy measurements. These results highlight the importance of modeling the nanoscale structure of the semiconductors for accurately reproducing intra-band transition energies of heavy carriers such as the holes. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4790305]

Optoelectronic Measurement Of X-Ray Synchrotron Pulses: A Proof Of Concept Demonstration, Stephen M. Durbin, Aamer Mahmood, Marc W. Caffee, Sergei Savikhin, Eric M. Dufresne, Haidan Wen, Yuelin Li

Birck and NCN Publications

Optoelectronic detection using photoconductive coplanar stripline devices has been applied to measuring the time profile of x-ray synchrotron pulses, a proof of concept demonstration that may lead to improved time-resolved x-ray studies. Laser sampling of current vs time delay between 12 keV x-ray and 800 nm laser pulses reveal the similar to 50 ps x-ray pulse width convoluted with the similar to 200 ps lifetime of the conduction band carriers. For GaAs implanted with 8 MeV protons, a time profile closer to the x-ray pulse width is observed. The protons create defects over the entire depth sampled by the x-rays, …

A Computational Approach To Optimize Microring Resonators For Biosensing Applications, Justin C. Wirth, B. R. Wenner, M. S. Allen, J. W. Allen, M. Qi

Birck and NCN Publications

Microcavity structures have recently found utility in chemical/biological sensing applications. The appeal of these structures over other refractive index-based sensing schemes, such as those based on surface plasmon resonance, lies in their potential for producing a highly sensitive response to binding events. High-Q devices, characterized by sharp line widths, are extremely attractive for sensing applications because the bound analyte provides an increased optical pathlength, thus shifting the resonant frequency of the device. In this work, we design and simulate resonant microrings using full-wave finite element models. In addition to structure design, integration of the biological recognition element on the resonator …

Red-Green-Blue Light Sensitivity Of Oxide Nanowire Transistors For Transparent Display Applications, Sumi Lee, Seongmin Kim, David B. Janes, M. Meyyappan, Sanghyun Ju

Birck and NCN Publications

In this study, the sensitivity of oxide nanowire transistors under red (R, 470 nm), green (G, 530 nm), and blue (B, 625 nm) light illumination was investigated. As the wavelength of light illuminating the nanowire channel region became shorter, a negative shift of threshold voltage, degradation of subthreshold slope, and increase of on-current were observed. This phenomenon can be explained in terms of photoinduced holes, creating interfacial traps between the gate dielectric and nanowire channel or reacting with oxygen ions on the surface of the nanowires. Thus, the attempt to minimize characteristic changes due to all RGB light sources was …

Implementation Of Quantum Logic Gates Using Polar Molecules In Pendular States, Jing Zhu, Sabre Kais, Qi Wei, Dudley Herschbach, Bretislav Friedrich

Birck and NCN Publications

No abstract provided.

Quantum Algorithm And Circuit Design Solving The Poisson Equation, Yudong Cao, Anargyros Papageorgiou, Iasonas Petras, Joseph Traub, Sabre Kais

Birck and NCN Publications

The Poisson equation occurs in many areas of science and engineering. Here we focus on its numerical solution for an equation in d dimensions. In particular we present a quantum algorithm and a scalable quantum circuit design which approximates the solution of the Poisson equation on a grid with error epsilon. We assume we are given a superposition of function evaluations of the right-hand side of the Poisson equation. The algorithm produces a quantum state encoding the solution. The number of quantum operations and the number of qubits used by the circuit is almost linear in d and polylog in …

Modeling Tools For Conformal Orthotic Devices, Steven David Riddle

Open Access Theses

The purpose of this thesis is to advance the design of conformal orthotic devices through the development of two modeling tools to address knowledge gaps in the field.

The field of human orthotics has been continually troubled by identifying successful methods of harnessing devices to the body. Past orthotics have utilized a rigid framework with minimal degrees of freedom (DOFs) driven by hard actuators attached to the body at select anchor points. Many devices design the structure and anchor points such that they reduce the degrees of freedom of a targeted joint, limiting the user's mobility and often causing the …

Characterization Of Heat And Mass Transport In Magnesium Hydride Hydrogen Storage Systems, Jennifer Anne Dadson

Open Access Theses

Hydrogen systems can provide viable alternatives for satisfying the world's energy requirements that both reduce dependency on and are more environmentally friendly than fossil fuels. For vehicular systems for example, hydrogen storage systems must have adequate gravimetric and volumetric storage capacities in addition to rapid uptake and release. Magnesium hydride shows good potential as a solid state hydrogen storage media due to its high gravimetric storage capacity of 7.6 wt% H₂; the highest of all reversible metal hydrides. Drawbacks, however, are its large reaction enthalpy of 78 kJ/mol for the desorption reaction and its low thermal conductivity of …

Design And Use Of An Adjustable Clearance Flailing Knife Biomass Shredder To Mechanically Increase Particle Surface Area, Shawn Gregory Ehlers

Open Access Theses

A flailing knife shredder was designed and tested as an alternative to a hammermill for processing biomass. The machine was comprised of two cylinders with four rungs, each with five free-swinging blades. Each of the two cylinders had adjustable clearance hoods and variable speed drives. Energy usage, output characteristics and device capacities were compared with corn stover processed at moisture contents (MC) of 10%, 35% and 50% wet basis (WB). The hammermill produced a more uniform particle size distribution in comparison to the shredder. Accessibility, indicated by conductivity index, to plant constituents, revealed that the method of treatment was not-significant …

Control Of Impacting Dynamical Systems, Akhil Salunke

Open Access Theses

Impacting systems are encountered frequently in nature, and often in mechanical systems. Impacts can be undesirable in some applications, and desirable and deliberate in others. A subset of impacting systems are vibro&ndashimpact systems, wherein the impacts arise during vibrations or oscillatory behavior. Considering their potential prominence in a number of day&ndashto&ndashday applications, such vibro&ndashimpact systems have become the subject of extensive research in the past few decades. A significant number of these studies have been specifically aimed at controlling vibro&ndashimpact systems. To date, a wide variety of control algorithms have been proposed, a subset of which account for the effects …

Turbulence Modeling For Subsonic Separated Flows Over 2-D Airfoils And 3-D Wings, Aaron Michael Rosen

Open Access Theses

Accurate predictions of turbulent boundary layers and flow separation through computational fluid dynamics (CFD) are becoming more and more essential for the prediction of loads in the design of aerodynamic flight components. Standard eddy viscosity models used in many commercial codes today do not capture the nonequilibrium effects seen in a separated flow and thus do not generally make accurate separation predictions. Part of the reason for this is that under nonequilibrium conditions such as a strong adverse pressure gradient, the history effects of the flow play an important role in the growth and decay of turbulence. More recent turbulence …

Detection Of Brain Abnormalities In Football Players Through Diffusion Weighted Imaging, Allan Emilio Diaz Gaez

Open Access Theses

Depression and cognitive impairment are commonly found in retired football players. Although they receive high magnitude hits to the head, the majority of the hits are sub-concussive, resulting in no clinical symptoms. Recent work using functional magnetic resonance (fMRI) and neurocognitive testing confirms that blows, causing changes in brain function, might not necessarily result in clinical diagnosis of concussion. Furthermore, cognitive deficiency in football players may be attributed to repetitive sub-concussive blows to the head. Diffusion weighted imaging (DWI) has previously been utilized to detect white matter (WM) abnormalities in mild traumatic brain injury (mTBI) patients, including those who have …

Effect Of Aviation Fuel Type And Fuel Injection Conditions On The Spray Characteristics Of Pressure Swirl And Hybrid Air Blast Fuel Injectors, Rick Thomas Feddema

Open Access Theses

Feddema, Rick T. M.S.M.E., Purdue University, December 2013. Effect of Aviation Fuel Type and Fuel Injection Conditions on the Spray Characteristics of Pressure Swirl and Hybrid Air Blast Fuel Injectors. Major Professor: Dr. Paul E. Sojka, School of Mechanical Engineering

Spray performance of pressure swirl and hybrid air blast fuel injectors are central to combustion stability, combustor heat management, and pollutant formation in aviation gas turbine engines. Next generation aviation gas turbine engines will optimize spray atomization characteristics of the fuel injector in order to achieve engine efficiency and emissions requirements.

Fuel injector spray atomization performance is affected by the …

Microstructural Evolution During Stress Relaxation Of Gold Thin Films, Luthfia Amra Syarbaini

Open Access Theses

Microstructure evolution in metal thin films for use in microelectronic devices was studied due to the formation of defects such as whiskers and hillocks that may cause problems in electrical circuits. Thin film stress relaxation can occur through a variety of processes. Understanding such mechanisms and the conditions under which certain mechanism dominate can potentially lead to the improved control of thin film stability. Studies of the 3D microstructural changes in Au thin films on silicon and other substrates with different thermal expansion coefficients aid us in understanding thin film relaxation phenomena such as hillock/whisker formation. Techniques such as in-situ …

Fundamentals Of Pv Efficiency Interpreted By A Two-Level Model, Muhammad A. Alam, Mohammad Ryyan Khan

Birck and NCN Publications

We consider the physics of photovoltaic (PV) energy conversion in a two-level, atomic PV and explain the conditions for which the Carnot efficiency is reached and how it can be exceeded. The loss mechanisms—thermalization, angle entropy, and below-bandgap transmission—explain the gap between Carnot efficiency and the Shockley-Queisser limit. Techniques developed to reduce these losses (e.g., solar concentrators, tandem cells, etc.) are reinterpreted using a simple two-level model. Remarkably, this simple model captures the essence of PV operation and reproduces the key results and important insights that that have been previously obtained using more complicated derivations.