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

Haiyan Tan, Ye Zhu, Christian Dwyer, Huolin L. Xin

Research output: Contribution to journalArticle

2 Citations (Scopus)

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 counterintuitive 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 counterintuitive "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. Implications for the interpretation of atomic-scale elemental maps are discussed.

Original languageEnglish (US)
Article number214305
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume90
Issue number21
DOIs
StatePublished - Dec 31 2014
Externally publishedYes

Fingerprint

Electron energy loss spectroscopy
Energy dissipation
Inelastic scattering
energy dissipation
electron energy
inelastic scattering
spectroscopy
Elastic scattering
elastic scattering
Electron scattering
thresholds
Electrons
Silicon
mean free path
quantitative analysis
electron scattering
electrons
Electron microscopes
electron microscopes
Single crystals

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

Energy-loss- and thickness-dependent contrast in atomic-scale electron energy-loss spectroscopy. / Tan, Haiyan; Zhu, Ye; Dwyer, Christian; Xin, Huolin L.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 90, No. 21, 214305, 31.12.2014.

Research output: Contribution to journalArticle

@article{22ee684bd4824e51bb9c7b4b9c303f05,
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 counterintuitive 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 counterintuitive {"}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. Implications for the interpretation of atomic-scale elemental maps are discussed.",
author = "Haiyan Tan and Ye Zhu and Christian Dwyer and Xin, {Huolin L.}",
year = "2014",
month = "12",
day = "31",
doi = "10.1103/PhysRevB.90.214305",
language = "English (US)",
volume = "90",
journal = "Physical Review B-Condensed Matter",
issn = "0163-1829",
publisher = "American Institute of Physics Publising LLC",
number = "21",

}

TY - JOUR

T1 - Energy-loss- and thickness-dependent contrast in atomic-scale electron energy-loss spectroscopy

AU - Tan, Haiyan

AU - Zhu, Ye

AU - Dwyer, Christian

AU - Xin, Huolin L.

PY - 2014/12/31

Y1 - 2014/12/31

N2 - 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 counterintuitive 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 counterintuitive "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. Implications for the interpretation of atomic-scale elemental maps are discussed.

AB - 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 counterintuitive 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 counterintuitive "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. Implications for the interpretation of atomic-scale elemental maps are discussed.

UR - http://www.scopus.com/inward/record.url?scp=84951102339&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84951102339&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.90.214305

DO - 10.1103/PhysRevB.90.214305

M3 - Article

VL - 90

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 0163-1829

IS - 21

M1 - 214305

ER -