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Title: Energy-loss- and thickness-dependent contrast in atomic-scale electron energy-loss spectroscopy

Abstract

Atomic-scale elemental maps of materials acquired by core-loss inelastic electron scattering often exhibit an undesirable sensitivity to the unavoidable elastic scattering, making the maps counter-intuitive to interpret. Here, we present a systematic study that scrutinizes the energy-loss and sample-thickness dependence of atomic-scale elemental maps acquired using 100 keV incident electrons in a scanning transmission electron microscope. For single-crystal silicon, the balance between elastic and inelastic scattering means that maps generated from the near-threshold Si-L signal (energy loss of 99 eV) show no discernible contrast for a thickness of 0.5λ (λ is the electron mean-free path, here approximately 110 nm). At greater thicknesses we observe a counter-intuitive “negative” contrast. Only at much higher energy losses is an intuitive “positive” contrast gradually restored. Our quantitative analysis shows that the energy-loss at which a positive contrast is restored depends linearly on the sample thickness. This behavior is in very good agreement with our double-channeling inelastic scattering calculations. We test a recently-proposed experimental method to correct the core-loss inelastic scattering and restore an intuitive “positive” chemical contrast. The method is demonstrated to be reliable over a large range of energy losses and sample thicknesses. The corrected contrast for near-threshold maps is demonstrated to bemore » (desirably) inversely proportional to sample thickness. As a result, implications for the interpretation of atomic-scale elemental maps are discussed.« less

Authors:
 [1];  [2];  [3];  [4]
  1. Univ. de Toulouse, Cedex (France); National Institute of Standards and Technology, Gaithersburg, MD (United States)
  2. Monash Univ., Melbourne, VIC (Australia)
  3. Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, and Peter Grunberg Institute, Julich (Germany)
  4. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Energy Materials Center at Cornell (EMC2); Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1182480
Alternate Identifier(s):
OSTI ID: 1180507
Report Number(s):
BNL-107273-2014-JA
Journal ID: ISSN 1098-0121; PRBMDO; R&D Project: 16060; KC0403020
Grant/Contract Number:  
SC00112704; AC02-98CH10886; DESC0001086
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 90; Journal Issue: 21; Journal ID: ISSN 1098-0121
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; EELS; STEM; spectroscopic mapping; preservation of elastic contrast

Citation Formats

Tan, Haiyan, Zhu, Ye, Dwyer, Christian, and Xin, Huolin L. Energy-loss- and thickness-dependent contrast in atomic-scale electron energy-loss spectroscopy. United States: N. p., 2014. Web. doi:10.1103/PhysRevB.90.214305.
Tan, Haiyan, Zhu, Ye, Dwyer, Christian, & Xin, Huolin L. Energy-loss- and thickness-dependent contrast in atomic-scale electron energy-loss spectroscopy. United States. https://doi.org/10.1103/PhysRevB.90.214305
Tan, Haiyan, Zhu, Ye, Dwyer, Christian, and Xin, Huolin L. 2014. "Energy-loss- and thickness-dependent contrast in atomic-scale electron energy-loss spectroscopy". United States. https://doi.org/10.1103/PhysRevB.90.214305. https://www.osti.gov/servlets/purl/1182480.
@article{osti_1182480,
title = {Energy-loss- and thickness-dependent contrast in atomic-scale electron energy-loss spectroscopy},
author = {Tan, Haiyan and Zhu, Ye and Dwyer, Christian and Xin, Huolin L.},
abstractNote = {Atomic-scale elemental maps of materials acquired by core-loss inelastic electron scattering often exhibit an undesirable sensitivity to the unavoidable elastic scattering, making the maps counter-intuitive to interpret. Here, we present a systematic study that scrutinizes the energy-loss and sample-thickness dependence of atomic-scale elemental maps acquired using 100 keV incident electrons in a scanning transmission electron microscope. For single-crystal silicon, the balance between elastic and inelastic scattering means that maps generated from the near-threshold Si-L signal (energy loss of 99 eV) show no discernible contrast for a thickness of 0.5λ (λ is the electron mean-free path, here approximately 110 nm). At greater thicknesses we observe a counter-intuitive “negative” contrast. Only at much higher energy losses is an intuitive “positive” contrast gradually restored. Our quantitative analysis shows that the energy-loss at which a positive contrast is restored depends linearly on the sample thickness. This behavior is in very good agreement with our double-channeling inelastic scattering calculations. We test a recently-proposed experimental method to correct the core-loss inelastic scattering and restore an intuitive “positive” chemical contrast. The method is demonstrated to be reliable over a large range of energy losses and sample thicknesses. The corrected contrast for near-threshold maps is demonstrated to be (desirably) inversely proportional to sample thickness. As a result, implications for the interpretation of atomic-scale elemental maps are discussed.},
doi = {10.1103/PhysRevB.90.214305},
url = {https://www.osti.gov/biblio/1182480}, journal = {Physical Review. B, Condensed Matter and Materials Physics},
issn = {1098-0121},
number = 21,
volume = 90,
place = {United States},
year = {Wed Dec 31 00:00:00 EST 2014},
month = {Wed Dec 31 00:00:00 EST 2014}
}

Journal Article:

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Cited by: 2 works
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