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Direct Observations of Defect Structures in Optoelectronic Materials by Z-Contrast STEM

Description: Optoelectronic semiconductor materials have wide and important technological applications. For example, wide gap nitride semiconductors have attracted significant attention recently due to their promising performance as short-wavelength light emitting diodes (LEDs) and blue lasers, while HgCdTe II-VI semiconductors are the most promising candidates for applications as infrared detectors, or large array x-ray or r-ray detectors. In this paper, two examples are given to show that high-resolution … more
Date: August 31, 1998
Creator: Beaumont, B.; Browning, N. D.; Chen, Y. P.; Faurie, J. P.; Gibart, P.; Nellist, P. D. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The Use Of Scanning Probe Microscopy To Investigate Crystal-Fluid Interfaces

Description: Over the past decade there has been a natural drive to extend the investigation of dynamic surfaces in fluid environments to higher resolution characterization tools. Various aspects of solution crystal growth have been directly visualized for the first time. These include island nucleation and growth using transmission electron microscopy and scanning tunneling microscopy; elemental step motion using scanning probe microscopy; and the time evolution of interfacial atomic structure using variou… more
Date: April 16, 2007
Creator: Orme, C. A. & Giocondi, J. L.
Item Type: Refine your search to only Book
Partner: UNT Libraries Government Documents Department
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Studying Nanoscale Magnetism and its Dynamics with Soft X-ray Microscopy

Description: Magnetic soft X-ray microscopy allows for imaging magnetic structures at a spatial resolution down to 15nm and a time resolution in the sub-100ps regime. Inherent elemental specificity can be used to image the magnetic response of individual components such as layers in multilayered systems. This review highlights current achievements and discusses the future potential of magnetic soft X-ray microscopy at fsec X-ray sources where snapshot images of ultrafast spin dynamics with a spatial resolut… more
Date: May 1, 2008
Creator: Mccall, Monnikue M & Fischer, Peter
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Partner: UNT Libraries Government Documents Department
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Local indium segregation and band structure in high efficiencygreen light emitting InGaN/GaN diodes

Description: GaN/InGaN light emitting diodes (LEDs) are commercialized for lighting applications because of the cost efficient way that they produce light of high brightness. Nevertheless, there is significant room for improving their external emission efficiency from typical values below 10 percent to more than 50 percent, which are obtainable by use of other materials systems that, however, do not cover the visible spectrum. In particular, green-light emitting diodes fall short in this respect, which is t… more
Date: November 23, 2004
Creator: Jinschek, Joerg R.; Erni, Rolf; Gardner, Nathan F.; Kim, AndrewY. & Kisielowski, Christian
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Partner: UNT Libraries Government Documents Department
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Microstructural and Microchemical Characterization of Dual Step Aged Alloy X-750 and its Relationship to Environmentally Assisted Cracking

Description: When exposed to deaerated high purity water, Alloy X-750 is susceptible to both high temperature (> 249 C) intergranular stress corrosion cracking (IGSCC) and intergranular low temperature (< 149 C) fracture (LTF). However, the microstructural and microchemical factors that govern environmentally assisted cracking (EAC) susceptibility are poorly understood. The present study seeks to characterize the grain boundary microstructure and microchemistry in order to gain a better mechanistic un… more
Date: May 8, 2001
Creator: Young, G.A.; Lewis, N.; Hanson, M.; Matuszyk, W.; Wiersma, B. & Gonzalez, S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Magnetic soft x-ray microscopy-imaging fast spin dynamics inmagnetic nanostructures

Description: Magnetic soft X-ray microscopy combines 15nm spatial resolution with 70ps time resolution and elemental sensitivity. Fresnel zone plates are used as X-ray optics and X-ray magnetic circular dichroism serves as magnetic contrast mechanism. Thus scientifically interesting and technologically relevant low dimensional nanomagnetic systems can be imaged at fundamental length and ultrafast time scales in a unique way. Studies include magnetization reversal in magnetic multilayers, nanopatterned syste… more
Date: June 1, 2007
Creator: Fischer, Peter; Kim, Dong-Hyun; Mesler, Brooke L.; Chao, Weilun; Sakdinawat, Anne E. & Anderson, Erik H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Z-contrast imaging and grain boundaries in semiconductors

Description: Interest in grain boundaries in semiconductors is linked to the application of polycrystalline semiconductors as photovoltaic and interconnect materials. In real devices such as solar cells and MOS structures as well as future devices such as flat-panel displays, the intergranular regions of the polycrystalline solid have a significant effect on the flow of electronic current. These grain boundary barriers exist because the chemical potential of the boundary atoms are shifted from the bulk valu… more
Date: March 1, 1996
Creator: Chisholm, M.F. & Pennycook, S.J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Structure of low-density nanoporous dielectrics revealed by low-vacuum electron microscopy and small-angle x-ray scattering

Description: We use low-vacuum scanning electron microscopy to image directly the ligament and pore size and shape distributions of representative aerogels over a wide range of length scales ({approx} 10{sup 0}-10{sup 5} nm). The images are used for unambiguous, real-space interpretation of small-angle scattering data for these complex nanoporous systems.
Date: June 5, 2006
Creator: Kucheyev, S O; Toth, M; Baumann, T F; Hamza, A V; Ilavsky, J; Knowles, W R et al.
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Partner: UNT Libraries Government Documents Department
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Lithographic measurement of EUV flare in the 0.3-NA Micro ExposureTool optic at the Advanced Light Source

Description: The level of flare present in a 0.3-NA EUV optic (the MET optic) at the Advanced Light Source at Lawrence Berkeley National Laboratory is measured using a lithographic method. Photoresist behavior at high exposure doses makes analysis difficult. Flare measurement analysis under scanning electron microscopy (SEM) and optical microscopy is compared, and optical microscopy is found to be a more reliable technique. In addition, the measured results are compared with predictions based on surface rou… more
Date: January 1, 2005
Creator: Cain, Jason P.; Naulleau, Patrick & Spanos, Costas J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Deformation of Microstructures Due to Low-Velocity Particulate Erosion of Ductile Metals by Spherical Particles

Description: A simple cumulative damage model has been developed for the low-velocity, normal-incidence, erosion of ductile metals by spherical particles. The model correlates the computed plastic-strain distribution for different impact velocities and materials with the experimentally measured erosion rates. This paper describes the surface and sub-surface changes which occur in Cu and Cu-6 wt % Al specimens during erosion testing. Scanning and transmission electron microscopy have been used to study these… more
Date: January 1, 1983
Creator: Follansbee, P.S.; Banerjee, D. & Williams, J.C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A CCD Camera with Electron Decelerator for Intermediate Voltage Electron Microscopy

Description: Electron microscopists are increasingly turning to Intermediate Voltage Electron Microscopes (IVEMs) operating at 300 - 400 kV for a wide range of studies. They are also increasingly taking advantage of slow-scan charge coupled device (CCD) cameras, which have become widely used on electron microscopes. Under some conditions CCDs provide an improvement in data quality over photographic film, as well as the many advantages of direct digital readout. However, CCD performance is seriously degraded… more
Date: March 17, 2008
Creator: Downing, Kenneth H; Downing, Kenneth H. & Mooney, Paul E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Scanning Transmission X-ray Microscopy: Applications in Atmospheric Aerosol Research

Description: Scanning transmission x-ray microscopy (STXM) combines x-ray microscopy and near edge x-ray absorption fine structure spectroscopy (NEXAFS). This combination provides spatially resolved bonding and oxidation state information. While there are reviews relevant to STXM/NEXAFS applications in other environmental fields (and magnetic materials) this chapter focuses on atmospheric aerosols. It provides an introduction to this technique in a manner approachable to non-experts. It begins with relevant… more
Date: January 20, 2011
Creator: Moffet, Ryan C.; Tivanski, Alexei V. & Gilles, Mary K.
Item Type: Refine your search to only Book
Partner: UNT Libraries Government Documents Department
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Investigation of defects and surface polarity in GaN using hot wet etching together with microscopy and diffraction techniques

Description: The availability of reliable and quick methods to determine defect density and polarity in GaN films is of great interest. We have used photo-electrochemical (PEC) and hot wet etching using H{sub 3}PO{sub 4} and molten KOH to estimate the defect density in GaN films grown by hydride vapor phase epitaxy (HVPE) and molecular beam epitaxy (MBE). Free-standing whiskers and hexagonal etch pits are formed by PEC and wet etching respectively. Using Atomic Force Microscopy (AFM), we found the whisker d… more
Date: April 8, 2002
Creator: Visconti, P.; Huang, D.; Reshchikov, M. A.; Yun, F.; Cingolani, R.; Smith, D. J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Failure Modes in High-Power Lithium-Ion Batteries for Use in Hybrid Electric Vehicles

Description: The Advanced Technology Development (ATD) Program seeks to aid the development of high-power lithium-ion batteries for hybrid electric vehicles. Nine 18650-size ATD baseline cells were tested under a variety of conditions. The cells consisted of a carbon anode, LiNi{sub 0.8}Co{sub 0.2}O{sub 2} cathode and DEC-EC-LiPF{sub 6} electrolyte, and they were engineered for high-power applications. Selected instrumental techniques such as synchrotron IR microscopy, Raman spectroscopy, scanning electron … more
Date: June 22, 2001
Creator: Kostecki, R.; Zhang, X.; Ross, Phillip N., Jr.; Kong, F.; Sloop, S.; Kerr, J. B. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Observation of Localized Corrosion of Ni-Based Alloys Using Coupled Orientation Imaging Microscopy and Atomic Force Microscopy

Description: We present a method for assessing the relative vulnerabilities of distinct classes of grain boundaries to localized corrosion. Orientation imaging microscopy provides a spatial map which identifies and classifies grain boundaries at a metal surface. Once the microstructure of a region of a sample surface has been characterized, a sample can be exposed to repeated cycles of exposure to a corrosive environment alternating with topographic measurement by an atomic force microscope in the same regi… more
Date: November 24, 1999
Creator: Bedrossian, P. J.
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Partner: UNT Libraries Government Documents Department
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Technology development for iron Fischer-Tropsch catalysts

Description: This report covers two aspects of the catalyst characterization studies: scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Two types of catalysts are the subject of this report: SEM studies with as-received, pretreated and used samples of a Ruhrchemie type catalyst and TEM examination of four crystal structures of FeOOH and Fe{sub 3}O{sub 4}.
Date: January 1, 1991
Creator: Davis, B. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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TiO2 Nanoparticles as a Soft X-ray Molecular Probe

Description: With the emergence of soft x-ray techniques for imaging cells, there is a pressing need to develop protein localization probes that can be unambiguously identified within the region of x-ray spectrum used for imaging. TiO2 nanocrystal colloids, which have a strong absorption cross-section within the "water-window" region of x-rays, areideally suited as soft x-ray microscopy probes. To demonstrate their efficacy, TiO2-streptavidin nanoconjugates were prepared and subsequently labeled microtubule… more
Date: June 30, 2007
Creator: Larabell, Carolyn; Ashcroft, Jared M.; Gu, Weiwei; Zhang, Tierui; Hughes, Steven M.; Hartman, Keith B. et al.
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Partner: UNT Libraries Government Documents Department
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TECHNIQUES FOR THE STUDY OF THE STRUCTURAL PROPERTIES.

Description: The evolution of our understanding of the behavior of oxide nanostructures depends heavily on the structural information obtained from a wide range of physical methods traditionally used in solid state physics, surface science and inorganic chemistry. In this chapter, we describe several techniques that are useful for the characterization of the structural properties of oxide nanostructures: X-ray diffraction (XRD) and scattering, X-ray absorption fine structure (XAFS), Raman spectroscopy, tran… more
Date: June 30, 2006
Creator: Fernandez-Garcia, M.; Rodriguez, J. A.; Martinez-Arias, A. & Hanson, J. C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Applications of Scanning Electron Microscopy to the Study of Mineral Matter in Peat

Description: Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) have been used for in situ analysis of minerals in peats by combining methods for producing oriented microtome sections of peat with methods for critical point drying. The combined technique allows SEM analysis of the inorganic components and their associated botanical constituents, along with petrographic identification of the botanical constituents. In peat deposits with abundant fluvial- or marine-derived minerals, o… more
Date: January 1, 1983
Creator: Raymond, R., Jr.; Andrejko, Michael J. & Bardin, Sharon W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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