A5019577418- Optical Coatings and Gratings
- Electron and X-Ray Spectroscopy Techniques
- Thin-Film Transistor Technologies
- Nuclear Materials and Properties
- Semiconductor materials and devices
- Silicon Nanostructures and Photoluminescence
- Nuclear Physics and Applications
- Diamond and Carbon-based Materials Research
- Carbon Nanotubes in Composites
- Photocathodes and Microchannel Plates
- Advanced X-ray Imaging Techniques
- Semiconductor materials and interfaces
- Calibration and Measurement Techniques
- Advancements in Photolithography Techniques
- Chalcogenide Semiconductor Thin Films
- Ion-surface interactions and analysis
- Advanced Semiconductor Detectors and Materials
- Silicon and Solar Cell Technologies
- Nuclear reactor physics and engineering
- Surface Roughness and Optical Measurements
- High-pressure geophysics and materials
- X-ray Spectroscopy and Fluorescence Analysis
- Adaptive optics and wavefront sensing
- Optical Systems and Laser Technology
- Metal and Thin Film Mechanics
Brigham Young University
2016-2025
Provo College
2009
Indiana University
2004
Pennsylvania State University
1996
Moxtek (United States)
1994
Center for Research and Advanced Studies of the National Polytechnic Institute
1994
Siemens (Germany)
1989
University of Arizona
1978-1981
Oak Ridge National Laboratory
1977-1978
Lawrence Berkeley National Laboratory
1972
Transition to a superconducting zero-resistance state at 155 K is observed for the first time in bulk material. A new five-element compound has been synthesized with nominal composition ${\mathrm{Y}}_{1}$${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{F}}_{2}$${\mathrm{O}}_{\mathrm{y}}$@B. Fluorine plays critical role achieving this effect. X-ray diffraction and electron microprobe analysis indicate that samples are multiphasic. Evidence presented contain phases onset temperatures...
Detecting and understanding the complex signatures of species for attribution highly enriched uranium, HEU, is challenging even though these compounds have been intensively studied 65 years. Attempts to obtain, example, chemical speciation on uranium oxides are frustrated by presence extremely diverse phases, structures, their tendency form solid solutions with coexistence many nonstoichiometric oxides. More importantly, spectroscopic oxides, using common techniques such as X-ray diffraction...
Depth profiles for hydrogen in amorphous silicon have been determined by the use of resonant nuclear reactions [1H(15N,αγ)12C and 1H(19F,αγ)16O] secondary ion mass spectroscopy (SIMS). Independent calibration procedures were used two techniques. Measurements made on same film to provide a direct comparison analysis The concentration bulk was be about 9 at.% H. SIMS results agree with reaction within 10%, which demonstrates that quantitative depth can obtained materials such as silicon.
We present an undergraduate optics instructional laboratory designed to teach skills relevant a broad range of modern scientific and technical careers. In this project, students image custom aperture using coherent diffraction imaging, while learning principles related digital processing computational including multidimensional Fourier analysis, iterative phase retrieval, noise reduction, finite dynamic range, sampling considerations. After briefly reviewing these imaging principles, we...
We have studied at cryogenic temperatures photoluminescence features which lie more than 0.15 eV below the band edge in ${\mathrm{Zn}}_{\mathit{x}}$${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$Te (0\ensuremath{\le}x\ensuremath{\le}0.09) crystals. The same features, namely a defect lies about 0.13--0.20 band-gap energy and peak 1.1 eV, that are observed pure CdTe samples these alloy materials. In annealed we observe 1.1-eV feature, has been attributed to tellurium vacancies, increases...
The crystalline quality of ZnxCd1−xTe single crystals prepared by a modified Bridgman method with 0≤x≤0.05 has been analyzed using photoluminescence. spectrum typical sample is dominated lines originating from the recombination free and bound excitons. Lines due to excitons in their ground first excited states are observed both pure CdTe mixed crystals. Excitons Cd vacancies crystal but not crystal. Weaker broader features appearing at energies below exciton emission range were associated...
In the first-order Raman spectrum of amorphous carbon (a-C) there is a low-frequency feature in 200--900-${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ region. This characteristic highly disordered amorphous-carbon materials. We note that intensity this very sensitive to thermal history samples, thus suggesting it an important measure degree disorder a-C also discuss relationship between and phonon density states graphite.
We use laser high-order harmonics and a polarization-ratio-reflectance technique to determine the optical constants of copper oxidized in wavelength range 10-35 nm. This measurement resolves previously conflicting data sets, where disagreement on extreme ultraviolet most likely arises from inadvertent oxidation samples before measurement.
This paper examines the effect of iron catalyst thickness on straightness growth carbon nanotubes (CNTs) for microelectromechanical systems fabricated using CNT-templated-microfabrication (CNT-M) process. SEM images samples grown various thicknesses show that both straight sidewalls and good edge definition are achieved an between 7 8 nm. Below this thickness, individual CNTs well aligned, but CNT forests formed into posts long walls not always straight. Above forest relatively straight, is...
A unique approach to detect chemical speciation and distribution on nanometer-scale nuclear materials has been achieved by the combination of neutron reflectometry shell-isolated surface-enhanced Raman spectroscopy. Both surface underlying layers uranium oxide were determined with angstrom-level resolution. Our results reveal that UO(x) film is composed three sublayers: an ∼38 Å thick layer U(3)O(8) formed along UO(x)/substrate interface; adjacent sublayer consists ∼900 single phase α-UO(3),...
Large grain polycrystalline and single crystals of ZnxCd1−xTe grown by a modified Bridgman method were studied using the photoluminescence photoconductivity techniques. The temperature dependence band gap, as determined photoluminescence, follows Varshni equation for measuring in range 15–290 K. One fitted parameters, Debye temperature, monotonically decreases with increase atomic zinc concentrations. A close correlation between measurements is also found. Samples which spectra exhibit...
Abstract A constrained non‐linear deconvolution method was used to analyse the Raman spectrum of amorphous carbon. The tested by applying it a model spectrum. Before observed smoothed least‐squares convoluting procedure. proper width spread function in determined examining reversibility process. result for carbon has form very similar phonon density states graphite. This is taken be additional evidence Shuker and Gamon's spectra materials. Potentially, can also other aspects analysis...
Hollow cathodes are a common type of vacuum ultraviolet (VUV) light source with wide range design and application. We determined the VUV (58.4 nm) intensity distribution hollow cathode as function current pressure. Our model describes McPherson 629-like helium plasma within 0.50–1.00 A Torr ring center peak. found that for all pressures currents considered, emits more than also peak has minimum emission near 0.9 Torr.
We have fabricated arrays of silicon field emitters using semiconductor lithography techniques. The density the tips was 105/cm2. maximum current that can be extracted from each emitter is limited by resistive heating. investigated how electron emitted changes under constant applied voltage. found very sensitive to vacuum conditions. attribute this sputtering due ionized residual gas molecules. poorer vacuum, higher instability in current. studied phenomenon at 10−6 and 10−8 Torr. model two...