Nanoscience and Nanotechnology Commons^™

Interface Trap Density Metrology From Sub-Threshold Transport In Highly Scaled Undoped Si N-Finfets, Abhijeet Paul, Giuseppe C. Tettamanz, Sunhee Lee, Saumitra R. Mehrotra, Nadine Collaert, Serge Biesemans, Sven Rogge, Gerhard Klimeck

Birck and NCN Publications

Channel conductance measurements can be used as a tool to study thermally activated electron transport in the sub-threshold region of state-of-art FinFETs. Together with theoretical Tight- Binding (TB) calculations, this technique can be used to understand the evolution of source-to- channel barrier height (Eb) and of active channel area (S) with gate bias (Vgs). The quantitative difference between experimental and theoretical values that we observe can be attributed to the interface traps present in these FinFETs. Therefore, based on the difference between measured and calculated values of (i) S and (ii) |∂Eb/∂Vgs| (channel to gate coupling), two new methods of …

Molecular Dynamics Characterization Of The Contact Between Clean Metallic Surfaces With Nanoscale Asperities, Hojin Kim, Alejandro Strachan

Birck and NCN Publications

We use molecular dynamics (MD) simulations to characterize the tensile strength of contacts formed between various clean platinum surfaces with nanoscale asperities. Both commensurate contacts between (001) and (111) surfaces and incommensurate (001) ones are considered over a wide range of asperity sizes. In cyclic closing and opening, fresh asperities that form contacts for the first time show significant plastic deformation; this leads to a reduction in the effective contact area during the first few cycles, after which steady state is achieved both in terms of contact size and the pull-out force necessary to open the contacts. As is the …

Lattice Thermal Conductivity Reduction In Bi2te3 Quantum Wires With Smooth And Rough Surfaces: A Molecular Dynamics Study, Bo Qiu, Lin Sun, Xiulin Ruan

Birck and NCN Publications

Using molecular dynamics simulations, we have predicted the thermal conductivity of Bi2Te3 nanowires with diameters ranging from 3 to 30 nm with both smooth and rough surfaces. It is found that when the nanowire diameter decreases to the molecular scale (below 10 nm, or the so-called "quantum wire"), the thermal conductivity shows significant reduction as compared to bulk value. On the other hand, the thermal conductivity for the 30-nm-diam nanowire only shows less than 20% reduction, in agreement with recent experimental data. Also, the thermal conductivity of nanowires shows a weaker temperature dependence than the typical T-1 trend, consistent with …

Phonon-Limited And Effective Low-Field Mobility In N- And P-Type [100]-, [110]-, And [111]-Oriented Si Nanowire Transistors, Mathieu Luisier

Birck and NCN Publications

Ultrascaled n- and p-type Si nanowire field-effect transistors (NW FETs) with [100], [110], and [111] as channel orientations are simulated in the presence of electron-phonon scattering using an atomistic quantum transport solver based on the sp(3)d(5)s* tight-binding model for electrons and holes, a modified Keating model for phonons, and the nonequilibrium Green's function formalism. The channel resistances of devices with different gate lengths and carrier concentrations are computed at room temperature and used to extract phonon-limited, ballistic, and effective low-field mobilities. It is found that a [110] channel represents the best choice for high n- and p-type NW FET performances. …

Effect Of Strain On Stripe Phases In The Quantum Hall Regime, Sunanda P. Koduvayur, Yuli Lyanda-Geller, Sergei Khlebnikov, Gabor Csathy, Michael J. Manfra, Loren N. Pfeiffer, Kenneth W. West, Leonid P. Rokhinson

Birck and NCN Publications

Preferential orientation of the stripe phases in the quantum Hall (QH) regime has remained a puzzle since its discovery. We show experimentally and theoretically that the direction of high and low resistance of the two-dimensional (2D) hole gas in the QH regime can be controlled by an external strain. Depending on the sign of the in-plane shear strain, the Hartree-Fock energy of holes or electrons is minimized when the charge density wave (CDW) is oriented along the [110] or [1 (1) over bar0] directions. We suggest that shear strains due to internal electric fields in the growth direction are responsible …

Modeling Diverse Physics Of Nanoparticle Self-Assembly In Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner

Mathematics Faculty Publications

Presents physics behind dewetting of thin liquid films and mathematical/computational modeling tools (Educational/Research presentation for senior physics majors).

Stability Of A Strongly Anisotropic Thin Epitaxial Film In A Wetting Interaction With Elastic Substrate, Mikhail Khenner, Wondimu T. Tekalign, Margo S. Levine

Mathematics Faculty Publications

The linear dispersion relation for longwave surface perturbations, as derived by Levine et al. Phys. Rev. B 75, 205312 (2007) is extended to include a smooth surface energy anisotropy function with a variable anisotropy strength (from weak to strong, such that sharp corners and slightly curved facets occur on the corresponding Wulff shape). Through detailed parametric studies it is shown that a combination of a wetting interaction and strong anisotropy, and even a wetting interaction alone results in complicated linear stability characteristics of strained and unstrained films.

Stability Of A Strongly Anisotropic Thin Epitaxial Film In A Wetting Interaction With Elastic Substrate, Mikhail Khenner, Wondimu Tekalign, Margo Levine

Mathematics Faculty Publications

The linear dispersion relation for longwave surface perturbations, as derived by Levine et al. Phys. Rev. B 75, 205312 (2007) is extended to include a smooth surface energy anisotropy function with a variable anisotropy strength (from weak to strong, such that sharp corners and slightly curved facets occur on the corresponding Wulff shape). Through detailed parametric studies it is shown that a combination of a wetting interaction and strong anisotropy, and even a wetting interaction alone results in complicated linear stability characteristics of strained and unstrained films.

Artificial And Natural Nucleic Acid Self Assembling Systems, Marcus Wood

Wayne State University Dissertations

Nucleic acids are good candidates for nanomachine construction. They participate in all the processes of life, and so can function as structural building blocks and dynamic catalysts. However, to use nucleic acids as nanomachines, a better understanding of their material properties, how to design structures using them, and their dynamics is needed. We have tried to address these issues, in a small way, with nucleic acid force field development, an attempt at nanostructural design and synthesis using DNA, and a study of the RNA/protein regulatory dynamics of the tryptophan regulatory attenuation protein.

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. …

Crystallite Phase And Orientation Determinations Of (Mn, Ga) As/Gaas-Crystallites Using Analyzed (Precession) Electron Diffraction Patterns, Ines Häusler, Stavros Nicolopoulos, Edgar F. Rauch, K. Volz, Peter Moeck

Physics Faculty Publications and Presentations

Outline of the presentation:

1. Material system: (Mn,Ga)As/GaAs-crystallites

2. Structure analysis using Nano-beam Diffraction (NBD) Precession Electron Diffraction Technique (PED) --> Structure type I + II

3. Phase and orientation mapping using ASTAR

4. Conclusion

Influence Of Cross-Section Geometry And Wire Orientation On The Phonon Shifts In Ultra-Scaled Si Nanowires, Abhijeet Paul, Mathieu Luisier, Gerhard Klimeck

Birck and NCN Publications

Engineering of the cross-section shape and size of ultra-scaled Si nanowires (SiNWs) provides an attractive way for tuning their structural properties. The acoustic and optical phonon shifts of the free-standing circular, hexagonal, square and triangular SiNWs are calculated using a Modified Valence Force Field (MVFF) model. The acoustic phonon blue shift (acoustic hardening) and the optical phonon red shift (optical softening) show a strong dependence on the cross-section shape and size of the SiNWs. The triangular SiNWs have the least structural symmetry as revealed by the splitting of the degenerate flexural phonon modes and The show the minimum acoustic hardening …

Effects Of Interface Roughness Scattering On Radio Frequency Performance Of Silicon Nanowire Transistors, Sunggeun Kim, Mathieu Luisier, Timothy B. Boykin, Gerhard Klimeck

Birck and NCN Publications

The effects of an atomistic interface roughness in n-type silicon nanowire transistors (SiNWT) on the radio frequency performance are analyzed. Interface roughness scattering (IRS) is statistically investigated through a three dimensional full–band quantum transport simulation based on the sp3d5s∗ tight–binding model. As the diameter of the SiNWT is scaled down below 3 nm, IRS causes a significant reduction of the cut-off frequency. The fluctuations of the conduction band edge due to the rough surface lead to a reflection of electrons through mode-mismatch. This effect reduces the velocity of electrons and hence the transconductance considerably causing a cut-off frequency reduction.

Effects Of Interface Disorder On Valley Splitting In Sige/Si/Sige Quantum Wells, Zhengping Jiang, Neerav Kharche, Timothy Boykin, Gerhard Klimeck

Birck and NCN Publications

A sharp potential barrier at the Si/SiGe interface introduces valley splitting (VS), which lifts the 2-fold valley degeneracy in strained SiGe/Si/SiGe quantum wells (QWs). This work examines in detail the effects of Si/SiGe interface disorder on the VS in an atomistic tight binding approach based on statistical sampling. VS is analyzed as a function of electric field, QW thickness, and simulation domain size. Strong electric fields push the electron wavefunctions into the SiGe buffer and introduce significant VS fluctuations from device to device. A Gedankenexperiment with ordered alloys sheds light on the importance of different bonding configurations on VS. We …

Shape And Orientation Effects On The Ballistic Phonon Thermal Properties Of Ultra-Scaled Si Nanowires, Abhijeet Paul, Mathieu Luisier, Gerhard Klimeck

Birck and NCN Publications

The effect of geometrical confinement, atomic position and orientation of Silicon nanowires (SiNWs) on their thermal properties are investigated using the phonon dispersion obtained using a Modified Valence Force Field (MVFF) model. The spe- cific heat (Cv) and the ballistic thermal conductance (κbal) shows anisotropic variation l with changing cross-section shape and size of the SiNWs. The Cv increases with de- creasing cross-section size for all the wires. The triangular wires show the largest Cv due to their highest surface-to-volume ratio. The square wires with [110] orientation show the maximum κbal since they have the highest number of conducting phonon …

Simulation Of Electrospun Nanofiber Deposition On Stationary And Moving Substrates, Linhua Liu, Yuris A. Dzenis

Department of Mechanical and Materials Engineering: Faculty Publications

Electrospinning produces continuous fibers with diameters from single nanometers to microns by jetting polymer solutions in high electric fields. Electrospun non-woven filamentary materials attract rapidly growing interest for broad range of applications. Properties of these materials depend on their nano- and microstructure that is determined in turn by the electric field and nanofiber collector. Despite critical importance, deposition of electrospun fibers on substrates has not yet been extensively studied theoretically and new methods of nanofiber collection continue to be developed mostly empirically. The objective of this Letter was to develop and demonstrate numerical simulation of electrospun nanofiber deposition on moving …

Modeling Of Solvent Evaporation From Polymer Jets In Electrospinning, Xiang-Fa Wu, Yury Salkovskiy, Yuris A. Dzenis

Department of Mechanical and Materials Engineering: Faculty Publications

Solvent evaporation plays a critical role in nanofiber formation in electrospinning. Here, we present a nonlinear mass diffusion-transfer model describing the drying process in dilute polymer solution jets. The model is used to predict transient solvent concentration profiles in polyacrylonitrile/ N,N-dimethylformamide (PAN/DMF) jets with the initial radii ranging from 50µm down to 100 nm. Numerical simulations demonstrate high transient inhomogeneity of solvent concentration over the jet cross-section in microscopic jets. The degree of inhomogeneity decreases for finer, submicron jets. The simulated jet drying time decreases rapidly with the decreasing initial jet radius, from seconds for microjets to single milliseconds for …

A Cell Electrofusion Microfluidic Device Integrated With 3d Thin-Film Microelectrode Arrays, Ning Hu, Jun Yang, Shizhi Qian, Sang W. Joo, Xiaolin Zheng

Mechanical & Aerospace Engineering Faculty Publications

A microfluidic device integrated with 3D thin film microelectrode arrays wrapped around serpentine-shaped microchannel walls has been designed, fabricated and tested for cell electrofusion. Each microelectrode array has 1015 discrete microelectrodes patterned on each side wall, and the adjacent microelectrodes are separated by coplanar dielectric channel wall. The device was tested to electrofuse K562 cells under a relatively low voltage. Under an AC electric field applied between the pair of the microelectrode arrays, cells are paired at the edge of each discrete microelectrode due to the induced positive dielectrophoresis. Subsequently, electric pulse signals are sequentially applied between the microelectrode arrays …

Dissemination Strategy For The Nanosafety Cluster 27.09.2011, Extra Deliverable 4.12 .Nanoimpactnet Report, Gordon Chambers, Iseult Lynch, Darren Hart, Nathalie Boschung, Byrony Ross, Sonja Grossberndt

Reports

So that the widest possible group of European nanosafety stakeholders are able to meet, interact, benefit from the work of NSC project members and work using reproducible methods using the same terms, there must be coordination. The following requirements should be clearly defined in the formulation of all new EC sponsored nanosafety-related projects and should be strongly encouraged in existing NSC projects:

Preparation And Characterization Of Iron Oxide And Hydroxide Based Nanomaterials, Guillermo Carbajal Franco

Open Access Theses & Dissertations

Iron (Fe) oxides and hydroxides are common and abundant materials. They exhibit diverse crystal structures, properties and phenomena by virtue of which they find a wide range of scientific and technological applications. Controlled growth and manipulation of the specific structure and electronic behavior to meet the requirements of a given application is a challenging problem in view of many possible phases and composition of the resulting materials. The preparation method and experimental conditions will, therefore, significantly affect the properties and performance of Fe oxides and hydroxides. The goal of the project is to obtain Fe-based oxide/hydroxide catalytic materials and to …

Intermediate Layers In Tandem Organic Solar Cells, Yongbo Yuan, Jinsong Huang, Gang Li

Department of Mechanical and Materials Engineering: Faculty Publications

Tandem structures can boost the efficiency of organic solar cell to more than 15%, compared to the 10% limit of single layer bulk heterojunction devices. Design and fabricating of intermediate layers plays a very important role to achieve high device performance. This article will review the main experimental progresses of tandem organic solar cells, and focus on the intermediate layers (charge recombination layers) in both thermal evaporated and solution processed organic tandem solar cell devices.

A Model Of Giant Vacuole Dynamics In Human Schlemm’S Canal Endothelial Cells, Ryan M. Pedrigi, David Simon, Ashley Reed, W. Daniel Stamer, Darryl R. Overby

Department of Mechanical and Materials Engineering: Faculty Publications

Aqueous humour transport across the inner wall endothelium of Schlemm’s canal likely involves flow through giant vacuoles and pores, but the mechanics of how these structures form and how they influence the regulation of intraocular pressure (IOP) are not well understood. In this study, we developed an in vitro model of giant vacuole formation in human Schlemm’s canal endothelial cells (HSCECs) perfused in the basal-to-apical direction (i.e., the direction that flow crosses the inner wall in vivo) under controlled pressure drops (2 or 6 mmHg). The system was mounted on a confocal microscope for time-lapse en face imaging, and cells …

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 …

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 …

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 …

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 …

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 …

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

Legacy Theses & Dissertations (2009 - 2024)

ABSTRACT

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

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.