Physics Commons^™

The Energetic And Wave Function Properties Of Atomic, Molecular, And Solid State Systems : H⁻ Ion And The Li, Ne, And P Atoms, Bf3·Nh3 Molecular Complex And Methyl Derivatives, V2+, Cr+, Mn2+, Mn0 Transition Metal Impurities In Silicon, Roger H. Pink

Legacy Theses & Dissertations (2009 - 2024)

The variational Hartree-Fock-Roothaan (HF) method with correlation corrections introduced through Many Body Perturbation Theory (MBPT) and the variational Density Functional Theory (DFT) have been investigated for atomic systems to provide insights into the strengths and weaknesses of each variational approach to solving the multicenter many-electron Hamiltonian. The HF+MBPT method, having been found to be more reliable and physically relevant from the atomic investigations, is used to investigate the electronic structures and associated properties of the BF3*NH3 molecular complex, and through cluster methods, the most likely locations of the transitional metal impurities V2+, Cr+, Mn2+ and Mn0 in Silicon.

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 …

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 Traditional thin layer SiO2 or SiOxNy films have been replaced by higher dielectric constant film stacks Here we study one example, the HfO2/La2O3/SiO2 stack.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 …

First Principles Investigation Of Electronic Structures And Associated Energy And Wave-Function Dependent Properties Of Biological Systems : Deoxyribonucleic Acid (Dna), Oxy-Haemoglobin, Shyam Raj Badu

Legacy Theses & Dissertations (2009 - 2024)

The Hartree-Fock procedure combined with many body perturbation theory has been used to investigate the electronic structures and associated properties of DNA systems and their corresponding muonium (Mu) adducts, as well as oxyhaemoglobin (HbO2).

Application Of X-Ray Diffraction To Material Analysis And Medical Imaging, Wei Zhou

Legacy Theses & Dissertations (2009 - 2024)

Powder diffraction is commonly used to determine the structures of both inorganic and organic materials. The angle and intensity of the diffraction (also called coherent scatter) peak depends on the nanostructure of the material. When no x-ray optic is used, the peak width broadens, and hence the resolution worsens, as the sample area is increased. However, a small sample area gives low diffracted signal intensity, particularly for thin films and for organic materials, which have low diffraction cross sections. X-ray optics can be used in x-ray powder diffraction to increase the diffraction intensity, thus decreasing exposure times. For a small …

Effects Of Deformation Ratio On The Mechanical Properties And Microstructures Changes In An Al-Mg-Si Alloy, Hichem Farh, Rebai Guemini, Serradj Fares, Karim Djemmal

Turkish Journal of Physics

An investigation has been done to study the effect of deformation ratio and two-step ageing treatment on the microstructure and the mechanical properties in an Al-Mg-Si aluminum alloy. Transmission electron microscopy is used in order to follow the distribution and the morphology of the hardening precipitates. The hardness of the alloy increases with the increasing deformation ratio. The maximum of hardness increases and is shifted to low time with an increase of the deformation ratio. The density of precipitates is more increased and the precipitates become more inhomogeneously distributed when the deformation combines with two-step ageing treatments.

Search For A Resonance Decaying Into Wz Boson Pairs In Pp Collisions, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration

Kenneth Bloom Publications

We present the first search for an electrically charged resonance W’ decaying to a WZ boson pair using 4.1 fb^-1 of integrated luminosity collected with the D0 detector at the Fermilab Tevatron pp collider. The WZ pairs are reconstructed through their decays into three charged leptons (ℓ = e, μ). A total of 9 data events is observed in good agreement with the background prediction. We set 95% C.L. limits on the W’WZ coupling and on the W’ production cross section multiplied by the branching fractions. We also exclude W’ masses between 188 and 520 …

Suppression Of Octahedral Tilts And Associated Changes In Electronic Properties At Epitaxial Oxide Heterostructure Interfaces, A. Y. Borisevich, H. Y. Chang, Mark Huijben, M. P. Oxley, S. Okamoto, Manish K. Niranjan, John D. Burton, Evgeny Y. Tsymbal, Y. H. Chu, P. Yu, R. Ramesh, Sergei V. Kalinin, S. J. Pennycook

Materials Research Science and Engineering Center: Faculty Publications

Epitaxial oxide interfaces with broken translational symmetry have emerged as a central paradigm behind the novel behaviors of oxide superlattices. Here, we use scanning transmission electron microscopy to demonstrate a direct, quantitative unit-cell-by-unit-cell mapping of lattice parameters and oxygen octahedral rotations across the BiFeO₃ -La_0:7 Sr_0:3MnO₃ interface to elucidate how the change of crystal symmetry is accommodated. Combined with low-loss electron energy loss spectroscopy imaging, we demonstrate a mesoscopic antiferrodistortive phase transition near the interface in BiFeO₃ and elucidate associated changes in electronic properties in a thin layer directly adjacent to the interface.

Collinear Phase Matching For Second Harmonic Generation Using Conoscopic Interferometry, A Puri, A De

Physics Faculty Publications

The problem of finding phase-matching directions in noncentrosymmetric biaxial crystals is simplified here by the use of Conoscopic interferometry. Based on vector relations for wave propagation in birefringent media and solutions to phase-matching equations, we show that phase matching directions can be located on the conoscopic interferograms and that fringe numbers for dark-isochromes can be used as a guide to find phase-matching directions for a biaxial crystal. This technique can be generalized and extended to any anisotropic crystal. We have demonstrated this method for the particular case of a biaxial KTiOPO₄ crystal, where it is found to be particularly …

Fabrication And Magnetic Properties Of Fe Nanostructures In Anodic Alumina Membrane, J H. Lim, W S. Chae, H O. Lee, L Malkinski, S G. Min, J B. Wiley, J H. Jun, S H. Lee, J S. Jung

Physics Faculty Publications

Several Fe nanostructures with different lengths, diameters, and separations of the constituting magnetic components have been synthesized using anodized alumina membranes (AAMs) to understand the influence of these parameters on their magnetic properties. Fe nanostructures with high crystallinity and (110) orientation were synthesized by electrodeposition at room temperature in regular AAMs and mild-hard AAM (Mi-Ha AAM). Fe nanostructures with different aspect ratios (1:1, 1:10, and 1:75) in the form of nanodots, nanorods, or nanowires were synthesized in regular AAMs with the 100 nm interpore distance. Mi-Ha AAMs with two different pore sizes (70 and 120 nm) and 250 nm interpore …

Lorentz Violation With An Antisymmetric Tensor, Brett David Altschul, Quentin G. Bailey, Alan Kostelecky

Faculty Publications

Field theories with spontaneous Lorentz violation involving an antisymmetric 2-tensor are studied. A general action including nonminimal gravitational couplings is constructed, and features of the Nambu-Goldstone and massive modes are discussed. Minimal models in Minkowski spacetime exhibit dualities with Lorentz-violating vector and scalar theories. The post-Newtonian expansion for nonminimal models in Riemann spacetime involves qualitatively new features, including the absence of an isotropic limit. Certain interactions producing stable Lorentz-violating theories in Minkowski spacetime solve the renormalization-group equations in the tadpole approximation.

Reflectivity Of A Cholesteric Liquid Crystal, Justin Lawson

Physics

In this paper we investigate the light properties of a chiral liquid crystal or a crystal for which the director angle relative to some fixed axis changes as a function of the crystal depth. Sometimes a dopant can introduce a chirality or "twist" in a nematic liquid crystal. For such cases of non-linear depth dependence (where chirality is determined by a diffusion equation) we may use this research to work backwards from a crystal's light properties to intensity and duration of dopant exposure.

A Study Of Structure-Property Correlation In V2o5 And Tio2 Based Thin Films As Functional Materials, Chandra Thapa

Wayne State University Dissertations

ABSTRACT

A STUDY OF STRUCTURE-PROPERTY CORRELATION IN V2O5 AND TiO2 BASED THIN FILMS AS FUNCTIONAL MATERIALS

by

CHANDRA THAPA

June 2010

Advisor: Dr. Ratna Naik

Co-Advisor: Dr. K. R. Padmanabhan

Major: Physics (Condensed Matter)

Degree: Doctor of Philosophy

The focus of this thesis is to study the structure-property correlation in thin films of V2O5 and TiO2 based transition metal oxides as functional materials. V2O5 is investigated as a cathode material for lithium ion battery and TiO2 as a high-K dielectric material.

We studied V2O5 thin films prepared by spin coating using three different types of precursors, MOD precursor, sol-gel organic …

A Search For The Sm Higgs Boson In The Process Zhllbb In 4.1/Fb Of Cdf Ii Data, Shalhout Zaki Shalhout

Wayne State University Dissertations

This dissertation presents a search for the standard model (SM) Higgs boson in the associated production process ZH → l⁺l_- bb using 4.1fb^-1 of Tevatron collision data collected with the CDF II detector.

To increase the sensitivity to a ZH signal over previous CDF searches, we implement new electron and expanded b-jet identification algorithms.

We utilize neural network classifiers enhanced with matrix element probabilities, a b-jet identifying neural network, and multivariate jet energy corrections to maximize the separation of signal from SM backgrounds.

We employ three neural network classifiers separately optimized for each of our three …

Vortex Dynamics In Superconducting Channels With Periodic Constrictions, Kang Yu, M.B.S. Hesselberth, P. H. Kes, B.L.T. Plourde

Physics - All Scholarship

Vortices confined to superconducting easy flow channels with periodic constrictions exhibit reversible oscillations in the critical current at which vortices begin moving as the external magnetic field is varied. This commensurability scales with the channel shape and arrangement, although screening effects play an important role. For large magnetic fields, some of the vortices become pinned outside of the channels, leading to magnetic hysteresis in the critical current. Some channel configurations also exhibit a dynamical hysteresis in the flux-flow regime near the matching fields.

Light Scalar Puzzle In Qcd, Amir H. Fariborz, Renata Jora, Joseph Schechter

Physics - All Scholarship

An approach to understanding the light scalar meson spectroscopy is briefly reviewed

Nonperturbative Results For Yang-Mills Theories, Francesco Sannino, Joseph Schechter

Physics - All Scholarship

Some non perturbative aspects of the pure SU(3) Yang-Mills theory are investigated assuming a specific form of the beta function, based on a recent modification by Ryttov and Sannino of the known one for supersymmetric gauge theories. The characteristic feature is a pole at a particular value of the coupling constant, g. First it is noted, using dimensional analysis, that physical quantities behave smoothly as one travels from one side of the pole to the other. Then it is argued that the form of the integrated beta function g(m), where m is the mass scale, determines the mass gap of …

Discreteness And The Transmission Of Light From Distant Sources, Fay Dowker, Joe Henson, Rafael Sorkin

Physics - All Scholarship

We model the classical transmission of a massless scalar field from a source to a detector on a background causal set. The predictions do not differ significantly from those of the continuum. Thus, introducing an intrinsic inexactitude to lengths and durations - or more specifically, replacing the Lorentzian manifold with an underlying discrete structure - need not disrupt the usual dynamics of propagation.

Plasmonic Light-Trapping And Quantum Efficiency Measurements On Nanocrystalline Silicon Solar Cells And Silicon-On-Insulator Devices, Eric A. Schiff, Hui Zhao, Birol Ozturk, Baojie Yan, Jeff Yang

Physics - All Scholarship

Quantum efficiency measurements in nanocrystalline silicon (nc-Si:H)solar cells deposited onto textured substrates indicate that these cells are close to the "stochastic lighttrapping limit" proposed by Yablonovitch in the 1980s. An interesting alternative to texturing is "plasmonic" light-trapping based on non-textured cells and using an overlayer of metallic nanoparticles to produce light-trapping. While this type of light-trapping has not yet been demonstrated for nc-Si:H solar cells, significant photocurrent enhancements have been reported on silicon-on-insulator devices with similar optical properties to nc-Si:H. Here we report our measurements of quantum efficiencies in nc-Si:H solar cells and normalized photoconductance spectra in SOI photodetectors with …

Characterization And Correction Of Dark Current In Compact Consumer Cameras, Justin Charles Dunlap, Erik Bodegom, Ralf Widenhorn

Physics Faculty Publications and Presentations

A study of dark current in digital imagers within consumer grade digital cameras is presented. Dark current is shown to vary with temperature, exposure time, and ISO setting. Further, dark current is shown to increase in successive images during a series of images. Consumer cameras are often designed to be as compact as possible and therefore the digital imagers within the camera frame are prone to heat generated by nearby elements within the camera body. It is the scope of this work to characterize the dark current in such cameras and to show that the dark current, in part due …