Atomic Resolution Electronic Structure Using Spatially Resolved Electron Energy Loss Spectroscopy

1994 ◽  
Vol 332 ◽  
Author(s):  
P.E. Batson
Keyword(s):  
Electronic Structure ◽  
High Energy ◽  
Dark Field ◽  
Atomic Resolution ◽  
Small Areas ◽  
Spatially Resolved ◽  
Spectral Interpretation ◽  
Core Excitations ◽  
Z Contrast ◽  
Electron Energy Loss

ABSTRACTElectronic structure in small areas is obtainable by inspection of near edge fine structure of core excitations. We can accomplish this today with near atomic resolution, using EELS at high energy. At IBM, we have obtained results using a sub-0.2nm probe at 120KeV with enough current to allow 200meV resolution studies at the Si L2,3 edge. It is especially crucial for Si-based structures that this allows us to obtain Z-contrast dark field images of the Si lattice at an acceleration voltage that is low enough to minimize radiation damage, but with a high enough current to allow good quality spectra to be obtained. A review of instrumental requirements, spectral interpretation, and applications to Si-Ge alloys is presented.

Local Electronic Structure Of Defects In Gan From Spatially Resolved Electron Energy-Loss Spectroscopy

1997 ◽  
Vol 482 ◽  
Author(s):  
M. K. H. Natusch ◽  
G. A. Botton ◽  
R. F. Broom ◽  
P. D. Brown ◽  
D. M. Tricker ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Crystal Defects ◽  
Vacuum Field ◽  
Spatially Resolved ◽  
Local Electronic Structure ◽  
Electron Energy Loss

AbstractThe optical properties and their modification by crystal defects of wurtzite GaN are investigated using spatially resolved electron energy-loss spectroscopy (EELS) in a dedicated ultra-high vacuum field emission gun scanning transmission electron microscope. The calculated density of states of the bulk crystal reproduces well the features of the measured spectra. The profound effect of a prismatic stacking fault on the local electronic structure is shown by the spatial variation of the optical properties derived from low-loss spectra. It is found that a defect state at the fault appears to bind 1.5 electrons per atom.

Experimental Measurement of the Local Electronic Structure of Grain Boundaries in Ni3Al

1993 ◽  
Vol 319 ◽  
Author(s):  
D.A. Muller ◽  
P.E. Batson ◽  
S. Subramanian ◽  
S. L. Sass ◽  
J. Silcox
Keyword(s):  
Electronic Structure ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Bulk Material ◽  
Local Strain ◽  
Dark Field ◽  
Hole Density ◽  
Spatially Resolved ◽  
Boron Segregation ◽  
Annular Dark Field

AbstractWe have examined grain boundaries in both undoped and boron doped Ni0.76Al0.24 using electron energy loss spectroscopy (EELS), x-ray fluorescence (EDX) and annular dark field (ADF) imaging in a UHV STEM. A detailed study of a high angle grain boundary in nickel rich Ni3Al doped with 1000 ppm boron shows nickel enrichment occurring in a 5Å wide region. Boron segregation to the boundary is observed with EELS and is seen to vary along the boundary, coinciding with ADF contrast changes in the surrounding grains that may be due to local strain fields. Spatially resolved EELS of the Ni L2,3 core edge, which is sensitive to changes in the hole density in the nickel d band, shows boron rich regions of the grain boundary to have a bonding similar to that of the bulk material. Boundary regions without boron have an electronic structure similar to that of the undoped grain boundaries where the Fermi level lies deeper in the nickel d band. In addition to studying boron segregation, EELS provides a unique opportunity to examine the changes in bonding that control the local properties of the material.

scholarly journals Effect of Al Addition on the Electronic Structure of Hafnia by Spatially Resolved Electron Energy Loss Spectroscopy

2006 ◽  
Vol 12 (S02) ◽  
pp. 1156-1157
Author(s):  
Q Li ◽  
J Dai ◽  
X Gong
Keyword(s):  
Electronic Structure ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Spatially Resolved ◽  
Al Addition ◽  
Electron Energy Loss

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

scholarly journals Optoelectronic Properties of Atomically Thin MoxW(1-x)S2 Nanoflakes Probed by Spatially-Resolved Monochromated EELS

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3218
Author(s):  
Mario Pelaez-Fernandez ◽  
Yung-Chang Lin ◽  
Kazu Suenaga ◽  
Raul Arenal
Keyword(s):  
Band Gap ◽  
2D Materials ◽  
High Energy ◽  
Two Dimensional ◽  
Low Loss ◽  
Huge Amount ◽  
Band Gap Engineering ◽  
Spatially Resolved ◽  
Excitonic Transition ◽  
Electron Energy Loss

Band gap engineering of atomically thin two-dimensional (2D) materials has attracted a huge amount of interest as a key aspect to the application of these materials in nanooptoelectronics and nanophotonics. Low-loss electron energy loss spectroscopy has been employed to perform a direct measurement of the band gap in atomically thin MoxW(1−x)S2 nanoflakes. The results show a bowing effect with the alloying degree, which fits previous studies focused on excitonic transitions. Additional properties regarding the Van Hove singularities in the density of states of these materials, as well as high energy excitonic transition, have been analysed as well.

Quantitative analysis of spatially resolved valence electron energy-loss spectra for electronic structure studies of grain boundaries and thin intergranular films

1995 ◽  
Vol 53 ◽  
pp. 314-315
Author(s):  
Roger H. French
Keyword(s):  
Electronic Structure ◽  
Quantitative Analysis ◽  
Spectral Line ◽  
Energy Loss ◽  
Grain Boundaries ◽  
Electron Energy ◽  
Valence Electron ◽  
Transition Strength ◽  
Spatially Resolved ◽  
Electron Energy Loss

The spatial variation of the electronic structure at interfaces is critical to both interatomic bonding at atomically abrupt interfaces such as grain boundaries and also to the development of van der Waals (vdW) attraction forces at partially wetted interfaces. This interfacial electronic structure, as represented by the interband transition strength , can be determined by Kramers Kronig (KK) analysis of either vacuum ultraviolet (VUV) optical reflectance spectra or spatially resolved valence electron energy loss (SR-VEEL) spectra. Quantitative analysis of SR-VEELS requires accurate spectral line shapes coupled with single scattering deconvolution, convergence correction, and KK analysis. Both the energy loss functions (Fig. 1) and the interband transitions (Fig. 2) determined for α-Al2O3 using SR-VEELS compare well with the VUV results. In addition the use of the spectral line scan method, whereby typically 200 SR-VEEL spectra are acquired along a scan line of 20 nm, helps overcome many uncertainties in the data acquisition and analysis.

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