Criteria and considerations for preparing atom-probe tomography specimens of nanomaterials utilizing an encapsulation methodology

Zhiyuan Sun, Ori Hazut, Roie Yerushalmi, Lincoln James Lauhon*, David N Seidman

*Corresponding author for this work

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Atom-probe tomography (APT) is a powerful method for characterization of nanomaterials due to its atomic-ppm level detection limit and Angstrom spatial resolution. Sample preparation for nanomaterials is, however, challenging because of their small dimensions and complicated geometries. Nanowires, with their high geometrical aspect ratio and nanowire length, 10 to 100 times their typical diameters, are highly suitable specimens for APT analyses, which can be transferred to silicon microposts using a nanomanipulator for direct APT measurements. This method is, however, prone to poor alignment and a limited field-of-view (FOV). Most importantly, direct implementation of APT with high aspect ratio nanowires may yield a low success rate of ∼30%, due to the high electric fields (10–40 V nm−1) associated with APT. While this is acceptable for samples analyzed solely by APT, a low sample yield makes it challenging to perform correlative experiments on the same nanowire specimen, utilizing other sophisticated characterization instruments. Herein, we introduce a general strategy for preparing high-yield APT specimens by encapsulating the nanowires utilizing a conformal atomic-layer deposition (ALD) coating followed by site-specific lift-out using a dual-beam focused-ion beam microscope. The ALD deposited coating forms strong chemical bonds with the Si nanowires yielding a high-quality and robust interface. The evaporation electric fields of the ALD coating and the nanowires are tuned by changing laser energy to obtain a uniform evaporation rate. The strong adhesion of the ALD-coating/nanowire interface and uniform evaporation rate produce a >90% specimen yield, with small concentration of reconstruction artifacts in 3-D. Simultaneously, the field-of-view is enhanced and the surface of the nanowire becomes visible, which makes the study of surface adsorption, segregation and oxidation possible. We utilized ALD-ZnO coated silicon nanowires as an example for investigating the criteria for choosing coating materials, laser pulse energy, laser direction, sample geometry, and substrate materials. The same criteria and considerations are applicable for preparing specimens of nanoparticles and 2-D material.

Original languageEnglish (US)
Pages (from-to)225-233
Number of pages9
JournalUltramicroscopy
Volume184
DOIs
StatePublished - Jan 1 2018

Fingerprint

Encapsulation
Nanostructured materials
Nanowires
Tomography
nanowires
tomography
methodology
Atoms
Atomic layer deposition
probes
atomic layer epitaxy
atoms
coatings
Coatings
Evaporation
evaporation rate
Silicon
field of view
Aspect ratio
Electric fields

Keywords

  • Atom-probe tomography
  • Atomic layer deposition
  • Encapsulation method
  • Nanowires
  • Sample preparation
  • Silicon

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Instrumentation

Cite this

@article{6392b3c1a7714bb7b40a1d8d861a4623,
title = "Criteria and considerations for preparing atom-probe tomography specimens of nanomaterials utilizing an encapsulation methodology",
abstract = "Atom-probe tomography (APT) is a powerful method for characterization of nanomaterials due to its atomic-ppm level detection limit and Angstrom spatial resolution. Sample preparation for nanomaterials is, however, challenging because of their small dimensions and complicated geometries. Nanowires, with their high geometrical aspect ratio and nanowire length, 10 to 100 times their typical diameters, are highly suitable specimens for APT analyses, which can be transferred to silicon microposts using a nanomanipulator for direct APT measurements. This method is, however, prone to poor alignment and a limited field-of-view (FOV). Most importantly, direct implementation of APT with high aspect ratio nanowires may yield a low success rate of ∼30{\%}, due to the high electric fields (10–40 V nm−1) associated with APT. While this is acceptable for samples analyzed solely by APT, a low sample yield makes it challenging to perform correlative experiments on the same nanowire specimen, utilizing other sophisticated characterization instruments. Herein, we introduce a general strategy for preparing high-yield APT specimens by encapsulating the nanowires utilizing a conformal atomic-layer deposition (ALD) coating followed by site-specific lift-out using a dual-beam focused-ion beam microscope. The ALD deposited coating forms strong chemical bonds with the Si nanowires yielding a high-quality and robust interface. The evaporation electric fields of the ALD coating and the nanowires are tuned by changing laser energy to obtain a uniform evaporation rate. The strong adhesion of the ALD-coating/nanowire interface and uniform evaporation rate produce a >90{\%} specimen yield, with small concentration of reconstruction artifacts in 3-D. Simultaneously, the field-of-view is enhanced and the surface of the nanowire becomes visible, which makes the study of surface adsorption, segregation and oxidation possible. We utilized ALD-ZnO coated silicon nanowires as an example for investigating the criteria for choosing coating materials, laser pulse energy, laser direction, sample geometry, and substrate materials. The same criteria and considerations are applicable for preparing specimens of nanoparticles and 2-D material.",
keywords = "Atom-probe tomography, Atomic layer deposition, Encapsulation method, Nanowires, Sample preparation, Silicon",
author = "Zhiyuan Sun and Ori Hazut and Roie Yerushalmi and Lauhon, {Lincoln James} and Seidman, {David N}",
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Criteria and considerations for preparing atom-probe tomography specimens of nanomaterials utilizing an encapsulation methodology. / Sun, Zhiyuan; Hazut, Ori; Yerushalmi, Roie; Lauhon, Lincoln James; Seidman, David N.

In: Ultramicroscopy, Vol. 184, 01.01.2018, p. 225-233.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Criteria and considerations for preparing atom-probe tomography specimens of nanomaterials utilizing an encapsulation methodology

AU - Sun, Zhiyuan

AU - Hazut, Ori

AU - Yerushalmi, Roie

AU - Lauhon, Lincoln James

AU - Seidman, David N

PY - 2018/1/1

Y1 - 2018/1/1

N2 - Atom-probe tomography (APT) is a powerful method for characterization of nanomaterials due to its atomic-ppm level detection limit and Angstrom spatial resolution. Sample preparation for nanomaterials is, however, challenging because of their small dimensions and complicated geometries. Nanowires, with their high geometrical aspect ratio and nanowire length, 10 to 100 times their typical diameters, are highly suitable specimens for APT analyses, which can be transferred to silicon microposts using a nanomanipulator for direct APT measurements. This method is, however, prone to poor alignment and a limited field-of-view (FOV). Most importantly, direct implementation of APT with high aspect ratio nanowires may yield a low success rate of ∼30%, due to the high electric fields (10–40 V nm−1) associated with APT. While this is acceptable for samples analyzed solely by APT, a low sample yield makes it challenging to perform correlative experiments on the same nanowire specimen, utilizing other sophisticated characterization instruments. Herein, we introduce a general strategy for preparing high-yield APT specimens by encapsulating the nanowires utilizing a conformal atomic-layer deposition (ALD) coating followed by site-specific lift-out using a dual-beam focused-ion beam microscope. The ALD deposited coating forms strong chemical bonds with the Si nanowires yielding a high-quality and robust interface. The evaporation electric fields of the ALD coating and the nanowires are tuned by changing laser energy to obtain a uniform evaporation rate. The strong adhesion of the ALD-coating/nanowire interface and uniform evaporation rate produce a >90% specimen yield, with small concentration of reconstruction artifacts in 3-D. Simultaneously, the field-of-view is enhanced and the surface of the nanowire becomes visible, which makes the study of surface adsorption, segregation and oxidation possible. We utilized ALD-ZnO coated silicon nanowires as an example for investigating the criteria for choosing coating materials, laser pulse energy, laser direction, sample geometry, and substrate materials. The same criteria and considerations are applicable for preparing specimens of nanoparticles and 2-D material.

AB - Atom-probe tomography (APT) is a powerful method for characterization of nanomaterials due to its atomic-ppm level detection limit and Angstrom spatial resolution. Sample preparation for nanomaterials is, however, challenging because of their small dimensions and complicated geometries. Nanowires, with their high geometrical aspect ratio and nanowire length, 10 to 100 times their typical diameters, are highly suitable specimens for APT analyses, which can be transferred to silicon microposts using a nanomanipulator for direct APT measurements. This method is, however, prone to poor alignment and a limited field-of-view (FOV). Most importantly, direct implementation of APT with high aspect ratio nanowires may yield a low success rate of ∼30%, due to the high electric fields (10–40 V nm−1) associated with APT. While this is acceptable for samples analyzed solely by APT, a low sample yield makes it challenging to perform correlative experiments on the same nanowire specimen, utilizing other sophisticated characterization instruments. Herein, we introduce a general strategy for preparing high-yield APT specimens by encapsulating the nanowires utilizing a conformal atomic-layer deposition (ALD) coating followed by site-specific lift-out using a dual-beam focused-ion beam microscope. The ALD deposited coating forms strong chemical bonds with the Si nanowires yielding a high-quality and robust interface. The evaporation electric fields of the ALD coating and the nanowires are tuned by changing laser energy to obtain a uniform evaporation rate. The strong adhesion of the ALD-coating/nanowire interface and uniform evaporation rate produce a >90% specimen yield, with small concentration of reconstruction artifacts in 3-D. Simultaneously, the field-of-view is enhanced and the surface of the nanowire becomes visible, which makes the study of surface adsorption, segregation and oxidation possible. We utilized ALD-ZnO coated silicon nanowires as an example for investigating the criteria for choosing coating materials, laser pulse energy, laser direction, sample geometry, and substrate materials. The same criteria and considerations are applicable for preparing specimens of nanoparticles and 2-D material.

KW - Atom-probe tomography

KW - Atomic layer deposition

KW - Encapsulation method

KW - Nanowires

KW - Sample preparation

KW - Silicon

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