scholarly journals Metallic line defect in wide-bandgap transparent perovskite BaSnO3

2021 ◽  
Vol 7 (3) ◽  
pp. eabd4449
Author(s):  
Hwanhui Yun ◽  
Mehmet Topsakal ◽  
Abhinav Prakash ◽  
Bharat Jalan ◽  
Jong Seok Jeong ◽  
...  
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Wide Bandgap ◽  
Line Defect ◽  
Defect Core ◽  
Transmission Electron ◽  
Ab Initio Theory ◽  
Metallic Line ◽  
Scanning Transmission ◽  
Line Defects ◽  
Electron Energy Loss

A line defect with metallic characteristics has been found in optically transparent BaSnO3 perovskite thin films. The distinct atomic structure of the defect core, composed of Sn and O atoms, was visualized by atomic-resolution scanning transmission electron microscopy (STEM). When doped with La, dopants that replace Ba atoms preferentially segregate to specific crystallographic sites adjacent to the line defect. The electronic structure of the line defect probed in STEM with electron energy-loss spectroscopy was supported by ab initio theory, which indicates the presence of Fermi level–crossing electronic bands that originate from defect core atoms. These metallic line defects also act as electron sinks attracting additional negative charges in these wide-bandgap BaSnO3 films.

scholarly journals Synthesis of nanosized vanadium(v) oxide clusters below 10 nm

2019 ◽  
Vol 21 (37) ◽  
pp. 21104-21108 ◽  
Author(s):  
Maximilian Lasserus ◽  
Daniel Knez ◽  
Florian Lackner ◽  
Martin Schnedlitz ◽  
Roman Messner ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy Loss Spectroscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Helium Droplets ◽  
Transmission Electron ◽  
Mean Diameter ◽  
Scanning Transmission ◽  
Electron Energy Loss

Vanadium oxide clusters with a mean diameter below 10 nm are created in helium droplets, and after deposition, studied by Scanning Transmission Electron Microscopy (STEM), Electron Energy Loss Spectroscopy (EELS) and UV-vis absorption spectroscopy.

Analysis of AlxGa1-xN nanowires through simulated methods of scanning transmission electron microscopy and electron energy-loss spectroscopy

2013 ◽  
Vol 6 (1) ◽  
Author(s):  
R. Kumar ◽  
P.J. Phillips ◽  
R.F. Klie
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Electron Energy Loss

AlxGa1-xN nanowires have promising applications in ultraviolet light emitting diodes (LEDs). However, these nanowires are not typical p-n junction semiconductors, but rather rely on varying concentrations of Al versus Ga to produce electron hole pairs. More information on the atomic structure is needed to better understand the properties of these nanowires. In this study, AlxGa1-xN nanowires were imaged using scanning transmission electron microscopy (STEM) and compared to computer simulated STEM images to obtain physical information on the nanowires. Electron energy-loss spectroscopy (EELS) and FEFF9 computer simulations were also performed to better understand the structural and chemical properties of the nanowires. Results from these simulations showed that changes in the chemical ordering of the nanowires were responsible for changes in intensity and resolution in the images. These intensity and resolution trends were not a result of interface effects. This will help to further characterize nanowires in the future.

scholarly journals Direct imaging of light-element impurities in graphene reveals triple-coordinated oxygen

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Christoph Hofer ◽  
Viera Skákalová ◽  
Tobias Görlich ◽  
Mukesh Tripathi ◽  
Andreas Mittelberger ◽  
...  
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Light Element ◽  
Single Atom ◽  
Nitrogen Forms ◽  
Rich Variety ◽  
Transmission Electron ◽  
Graphene Lattice ◽  
Scanning Transmission ◽  
Electron Energy Loss ◽  
Aberration Corrected

Abstract Along with hydrogen, carbon, nitrogen and oxygen are the arguably most important elements for organic chemistry. Due to their rich variety of possible bonding configurations, they can form a staggering number of compounds. Here, we present a detailed analysis of nitrogen and oxygen bonding configurations in a defective carbon (graphene) lattice. Using aberration-corrected scanning transmission electron microscopy and single-atom electron energy loss spectroscopy, we directly imaged oxygen atoms in graphene oxide, as well as nitrogen atoms implanted into graphene. The collected data allows us to compare nitrogen and oxygen bonding configurations, showing clear differences between the two elements. As expected, nitrogen forms either two or three bonds with neighboring carbon atoms, with three bonds being the preferred configuration. Oxygen, by contrast, tends to bind with only two carbon atoms. Remarkably, however, triple-coordinated oxygen with three carbon neighbors is also observed, a configuration that is exceedingly rare in organic compounds.

Buttons and Threads—Tailoring Defect Analysis

2006 ◽  
Author(s):  
Carolyn F. H. Gondran ◽  
Dennis F. Paul ◽  
Sanjit K. Das ◽  
Brendan J. Foran ◽  
Mark H. Clark
Keyword(s):  
Electron Spectroscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Auger Electron ◽  
Defect Analysis ◽  
Transmission Electron ◽  
Analysis Technique ◽  
Small Defect ◽  
Scanning Transmission ◽  
Auger Microscopy ◽  
Electron Energy Loss

Abstract A framework is presented for considering the relative strengths of Auger electron spectroscopy (AES)/scanning Auger microscopy (SAM) and scanning transmission electron microscopy–electron energy loss spectroscopy (STEM-EELS) when selecting a defect analysis technique. The geometry of the analysis volumes for each technique is visualized. The analysis volume for AES/SAM is shaped like a button while the STEM-EELS analysis volume is more like a thread extending throughout the thickness of the prepared sample. The usefulness of this framework is illustrated with the example of small defect particles. In this example the size and shape of the AES/SAM analysis volume is a better fit to the defect, thus it provides better chemical analysis while STEM provides better images of the defects.

Quantitative EELS Analysis of AlGaN Nanowires Grown by Ni Promoted MBE on Sapphire Substrate

2007 ◽  
Vol 1026 ◽  
Author(s):  
Leonardo Lari ◽  
Robert T Murray ◽  
Mhairi H Gass ◽  
Timothy J Bullough ◽  
Paul R Chalker ◽  
...  
Keyword(s):  
Solid Solution ◽  
Scanning Transmission Electron Microscopy ◽  
Molecular Beam ◽  
Equilibrium Phase ◽  
Oxide Shell ◽  
Transmission Electron ◽  
Frequency Plasma ◽  
Scanning Transmission ◽  
Electron Energy Loss ◽  
N Compounds

AbstractQuantitative analysis of the elemental distributions within AlGaN has been investigated using electron energy loss spectroscopy in a scanning transmission electron microscopy. The nanowires were grown on c-sapphire by radio frequency plasma assisted molecular beam epitaxy. Crystallographic and compositional analyses of the nickel seeds used to promote the nanowire type growth yielded values of lattice spacings within the seeds remaining at the growth tip which were attributed to either (002) NiO, (111) Ni3Ga or (111) Ni-Ga solid solution. The seeds structures exhibited a metallic core encompassed by an oxide shell. The relative gallium and nickel concentrations were quantified by EELS analyses and were found to be consistent with the equilibrium phase α' of Ni3Ga or Ni-Ga solid solution. No nitrogen was observed within the seeds, which is predicted thermodynamically due to the instability of Ni-N compounds at the NW growth temperature used in this study. No aluminium was detected at the tip of nanowires. These measurements are compared with previous studies made concerning pure GaN nanowires. The Al distribution along the nanowire length was measured and is discussed in respect of a possible Al incorporation mechanism.

Mapping Chemical Bonds in Semiconductor Devices by Monitoring the Shifts of EELS Edges

2017 ◽  
Vol 23 (5) ◽  
pp. 926-931 ◽  
Author(s):  
Pavel Potapov ◽  
Elena L. Svistunova ◽  
Alexander A. Gulyaev
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Core Loss ◽  
Least Square ◽  
Reference Spectrum ◽  
Low Loss ◽  
Edge Structure ◽  
Simultaneous Acquisition ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Electron Energy Loss

AbstractScanning transmission electron microscopy (STEM) in combination with electron energy-loss spectroscopy (EELS) can deliver information about variations of bonding at the nm scale. This is typically performed by analyzing the electron-loss near edge structure (ELNES) of given EELS edges. The present paper demonstrates an alternative way of a bonding examination through monitoring the EELS onset positions. Two conditions are essential for their accurate measurement. One (hardware) is using the dual EELS instrumentation that provides near simultaneous acquisition of low-loss and core-loss spectra. Another (software) is the least-square fitting of observed spectra to a reference spectrum. The combination of these hardware and software techniques reveals the positions of EELS onsets with the precision sufficient for mapping tiny variations of bonding. The paper shows that the method is capable of helping to solve practical tasks of nanoscale engineering like the analysis of modern CMOS devices.

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