A5004822979- Semiconductor materials and devices
- Diamond and Carbon-based Materials Research
- Semiconductor materials and interfaces
- GaN-based semiconductor devices and materials
- Metal and Thin Film Mechanics
- Thin-Film Transistor Technologies
- Silicon Nanostructures and Photoluminescence
- Surface and Thin Film Phenomena
- Ga2O3 and related materials
- Electronic and Structural Properties of Oxides
- Ion-surface interactions and analysis
- Silicon and Solar Cell Technologies
- Silicon Carbide Semiconductor Technologies
- Electron and X-Ray Spectroscopy Techniques
- Force Microscopy Techniques and Applications
- Advanced Materials Characterization Techniques
- Semiconductor Quantum Structures and Devices
- ZnO doping and properties
- Graphene research and applications
- Carbon Nanotubes in Composites
- Plasma Diagnostics and Applications
- Intermetallics and Advanced Alloy Properties
- Acoustic Wave Resonator Technologies
- Copper Interconnects and Reliability
- Advancements in Semiconductor Devices and Circuit Design
Arizona State University
2016-2025
Fox Corporation (United States)
2016-2019
Xerox (France)
2016-2019
Teledyne Technologies (United States)
2017-2018
Technical University of Denmark
2017-2018
University of Michigan
1999-2018
North Carolina State University
2004-2017
University of California, Davis
2017
Lawrence Livermore National Laboratory
2017
Nanjing University of Science and Technology
2017
First- and second-order Raman scattering from graphite has been studied. The spectra of single crystals highly oriented pyrolytic are continuous exhibit several well-defined bands which can be attributed to features in the density vibrational states as determined current lattice-dynamics models. deduced model Nicklow, Wakabayashi, Smith provides best replication spectrum, but is nevertheless somewhat deficient this regard, need improvement. dependence first- on crystallite size also studied...
Abstract Ultrawide‐bandgap (UWBG) semiconductors, with bandgaps significantly wider than the 3.4 eV of GaN, represent an exciting and challenging new area research in semiconductor materials, physics, devices, applications. Because many figures‐of‐merit for device performance scale nonlinearly bandgap, these semiconductors have long been known to compelling potential advantages over their narrower‐bandgap cousins high‐power RF electronics, as well deep‐UV optoelectronics, quantum...
The ir and Raman spectra of $a$-Si: H alloys produced by plasma decomposition Si${\mathrm{H}}_{4}$ are studied for a wide range deposition conditions. vibrational display modes which can be characterized as predominantly hydrogen motions. Analysis these shows four types local Si-H bonding environments identified SiH, Si${\mathrm{H}}_{2}$, Si${\mathrm{H}}_{3}$, coupled Si${\mathrm{H}}_{2}$ or ${(\mathrm{Si}{\mathrm{H}}_{2})}_{n}$ units. On the basis identifications, it is found that samples...
The atomic bonding configurations of carbon in diamond and diamondlike thin films are explored using Raman scattering. general aspects scattering from composites presented. Effects discussed due to crystalline or amorphous structures, large versus microcrystalline domains, strong optical absorption transparent regions. shows several features which attributed graphitelike structures all originate the same region sample. In contrast, spectra show different components a composite film....
The optimization of diamond films as valuable engineering materials for a wide variety applications has required the development robust methods their characterization. Of many used, Raman microscopy is perhaps most because it provides readily distinguishable signatures each different forms carbon (e.g. diamond, graphite, buckyballs). In addition non-destructive, requires little or no specimen preparation, performed in air and can produce spatially resolved maps within specimen. This article...
Raman scattering and x-ray diffraction measurements are used to correlate finite-size effects on the spectra of nonpolar vibrational modes in BN. The BN microcrystalline samples exhibited domain sizes varying from 4.4 78.5 nm plane 1.5 47.5 perpendicular planes. indicated that high-frequency ${E}_{2g}$ mode shifted higher frequency broadened as crystallite size decreased. A formulation cross section for microcrystals is presented. development includes evaluation susceptibility correlation...
Diamond and diamondlike thin films produced by various chemical-vapor-deposition processes have been examined using Raman spectroscopy. These exhibit features in the spectra, suggesting that they are composites of crystalline amorphous diamond graphitic structures. The components this composite structure contribute to scattering discussed terms ${\mathrm{sp}}^{2}$- ${\mathrm{sp}}^{3}$-bonded use spectroscopy as a technique for estimating ${\mathrm{sp}}^{2}$-to-${\mathrm{sp}}^{3}$ bonding...
It is demonstrated that hydrogenation induces microdefects and electronic deep levels in single-crystal silicon, which are unrelated to either plasma or radiation damage. After of n-type p-type transmission electron microscopy reveals defects can be described as hydrogen-stabilized platelets microcracks appear within 0.1 \ensuremath{\mu}m the exposed surface predominantly oriented along {111} crystallographic planes. These correlate with high concentrations hydrogen deuterium measured by...
A negative electron affinity (NEA) was found both experimentally by photoemission spectroscopy and theoretically ab initio calculations for the 2\ifmmode\times\else\texttimes\fi{}1 reconstructed diamond (100) surface. This surface is dominant growth thin films can be obtained chemical-vapor deposition. Various surface-preparation methods which result in a NEA are described. Theoretical results indicate that observed associated with monohydride-terminated surface, while hydrogen-free exhibits...
Reverse bias current–voltage measurements of ∼100-μm-diameter gold Schottky contacts deposited on as-received, n-type ZnO(0001̄) wafers and those exposed for 30 min to a remote 20% O2/80% He plasma at 525±20 °C cooled either in vacuum from 425 or the unignited gas have been determined. Plasma cleaning resulted highly ordered, stoichiometric, smooth surfaces. Contacts as-received material showed μA leakage currents ideality factors >2. plasma-cleaned ∼36±1 nA current −4 V, barrier...
GaN and AlGaN have shown great potential in next-generation high-power electronic devices; however, they are plagued by a high density of interface states that affect device reliability performance, resulting large leakage current collapse. In this review, the authors summarize understanding gate collapse mechanisms, where awareness surface defects is key to controlling improving performance. With mind, present research on AlGaN-based heterostructures. Since GaNand polar materials, both...
Successful ex situ and in cleaning procedures for AlN GaN surfaces have been investigated achieved. Exposure to HF HCl solutions produced the lowest coverages of oxygen on surfaces, respectively. However, significant amounts residual F Cl were detected. These halogens tie up dangling bonds at nitride hindering reoxidation. The desorption required temperatures >850 °C. Remote H plasma exposure was effective removing hydrocarbons from both nitrides 450 °C, but not efficient oxide...
An atomic force microscope (AFM) is used to measure the magnitude of effective longitudinal piezoelectric constant (d33) thin films. Measurements are performed with a conducting diamond AFM tip in contact top electrode. The interaction between and electric field present potentially large source error that eliminated through use this configuration tips. yielded reasonable constants X-cut single-crystal quartz, film ZnO, nonpiezoelectric SiO2
Stress-induced changes in the imprint and switching behavior of (111)-oriented Pb(Zr,Ti)O3 (PZT)-based capacitors have been studied using piezoresponse force microscopy. Visualization polarization distribution d33-loop measurements individual 1×1.5-μm2 before after stress application, generated by substrate bending, provided direct experimental evidence stress-induced switching. Mechanical caused elastic with direction resulting determined sign applied stress. In addition, application turned...
The structure of evaporated ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$, ${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$, and Ge${\mathrm{Se}}_{2}$ films, the influence annealing at glasstransition temperature, are studied by extended x-ray-absorption fine (EXAFS) Raman spectroscopy. In addition, topology each film is analyzed calculating x-ray diffraction for several models. films were prepared evaporation onto substrates held near room temperature. All as-deposited exhibited significant homopolar bonding...
The formation mechanisms and properties of TiSi2 on Si are investigated. particular emphasis is in relating the nucleation, morphology, phase stability films. films were prepared by deposition Ti atomically clean silicon substrates ultrahigh vacuum. silicide was initiated either situ annealing or onto heated substrates. island surface interface morphologies examined scanning electron microscopy transmission microscopy. process monitored with Auger spectroscopy low-energy diffraction to...
An experimental approach for direct studies of the polarization reversal mechanism in thin film ferroelectric capacitors based on piezoresponse force microscopy (PFM) conjunction with pulse switching capabilities is presented. Instant domain configurations developing a 3×3μm2 capacitor at different stages process have been registered using step-by-step and subsequent PFM imaging. The developed allows comparison experimentally measured microscopic behavior parameters used by phenomenological...
This study demonstrates the presence of a negative electron affinity (NEA) surface on AlN was grown α(6H)-SiC. Heteroepitaxial α(6H)-SiC(0001) substrates by molecular beam epitaxy techniques. The electronic states were characterized ultraviolet photoemission obtained at normal. observation sharp spectral feature lowest energy emitted electrons is an indication with affinity. In addition, trend NEA examined as function annealing. Fermi level found to be near middle gap, and possible band...
The kinetics of sidewise domain growth in an inhomogeneous electric field has been investigated stoichiometric LiNbO3 single crystals by measuring the lateral size as a function voltage pulse magnitude and duration using piezoresponse force microscopy. increases linearly with suggesting that is kinetically limited wide range magnitudes durations. In spite that, written domains exhibit strong retention behavior. It suggested switching behavior can be described universal scaling curve. Domain...
Polarized low-frequency Raman and Brillouin spectra of the chalcogenide glasses ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$, Ge${\mathrm{S}}_{2}$, Ge${\mathrm{Se}}_{2}$, ${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$ glass alloy system ${({\mathrm{As}}_{2}{\mathrm{S}}_{3})}_{1\ensuremath{-}x}{(\mathrm{Ge}{\mathrm{S}}_{2})}_{x}$ have been measured using near infrared 7525 or 7993 \AA{} lines a krypton laser. The low-temperature $T\ensuremath{\sim}10$ K four binary indicate that coupling constant exhibits...
Abstract Infra-red and Raman spectra have been obtained from thin films of silicon-hydrogen silicon-hydrogen-deuterium alloys deposited low pressure, r.f. excited plasmas in mixtures SiH4/Ar SiH4/D2/Ar respectively. The are analysed using a valence-force-field model based on effective force constants determined SiH4. For onto substrates held at 25°C it is concluded that the structure best described as pseudobinary alloy form (Si)x(Si2H4)1_ x . In contrast, for material to substrate...