Low-Energy Electron Diffraction Patterns Using Field-Emitted Electrons from Tungsten Tips

Mizuno, Seigi; Rahman, F.; Iwanaga, Masayuki

doi:10.1143/jjap.45.l178

Cited by 21 publications

(12 citation statements)

References 10 publications

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“…Field emissions (FEs) from atomically sharp tips have high brightness and spatial coherency. These properties make them of interest for use as point FE guns in lens-less applications, such as scanning Auger electron microscopy [1], projection microscopy [2], near-field emission scanning electron microscopy [3] and low-energy electron diffraction on the sub-micron order [4]. For these high-resolution electron-beam instruments, the apex structures of tips are crucial.…”

Section: Introductionmentioning

confidence: 99%

STEM observation of tungsten tips sharpened by field-assisted oxygen etching

2010

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Tungsten tips oriented toward the <111> direction were fabricated by field-assisted O 2 etching, and observed by means of scanning transmission electron microscopy (STEM) and field ion microscopy (FIM). The radii of curvature of the tip apexes were sharpened from 16-20 nm to less than 2 nm. The O 2 etching is considered to start from the O 2 imaging region depending on the field distribution around the tip apex and shank. We estimated the effect of field distribution derived from a shank shape and applied bias voltage. The results showed that the tip with a cylindrical shank before the O 2 etching became sharper than tips having an initial paraboloidal shape, with respective cone angles (defined in Fig. 3) of 58° and 80°. The field emission (FE) patterns of these etched tips became a single spot derived from the W(111) plane, and their opening angles (defined by the full width at half maximum) were 14.4° and 7.8°, respectively.

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Section: Introductionmentioning

confidence: 99%

STEM observation of tungsten tips sharpened by field-assisted oxygen etching

2010

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“…In this report, we present the relations between field emissions (FE) and the geometries of tips prepared by field-assisted N 2 and O 2 etching. Such detailed data are indispensable for the successful application of tips fabricated by this method in fields such as electron microscopy, projection microscopy [11,12], scanning Auger electron microscopy [13], point-reflection electron microscopy [14], and field emission low-energy electron diffraction [15]. We fabricated sharp tips using N 2 and O 2 etching because these fabrications enabled us to control the tip sharpness.…”

Section: Introductionmentioning

confidence: 99%

Field Emission from W Tips Sharpened by Field-Assisted Nitrogen and Oxygen Etching

Onoda

Rahman

Mizuno

2008

e-J. Surf. Sci. Nanotechnol.

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Field emission properties were studied for tips sharpened using field-assisted nitrogen and oxygen etching. Sharp single crystal tungsten <111>-oriented tips were fabricated and evaluated by Fowler-Nordheim plots and field-ion microscopy observations. The results demonstrated emissions at lower bias voltages due to the sharpening of the tip apex using the etching. The field emission properties and tip shapes after nitrogen etching were compared with those obtained after oxygen etching.

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“…11 Such an experiment has already produced diffraction patterns from areas as small as 400 m across, with areas smaller than 50 nm across being possible. Electron beams have in fact been focused to such dimensions in various applications.…”

Section: Introductionmentioning

confidence: 99%

Theory of low-energy electron diffraction for detailed structural determination of nanomaterials: Ordered structures

Gavaza

Tsang

et al. 2007

Phys. Rev. B

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To enable the determination of detailed structures of nanomaterials, we extend the theory of low-energy electron diffraction ͑LEED͒ to become more efficient for complex and disordered systems. Our new cluster approach speeds up the computation to scale as n log n, rather than the current n 3 or n 2 , with n the number of atoms, for example, making nanostructures accessible. Experimental methods to measure LEED data already exist or have been proposed. Potential application to ordered nanoparticles are illustrated here for C 60 molecules adsorbed on a Cu͑111͒ surface, with and without coadsorbed metal atoms, as well as for adsorbed carbon nanotubes. These demonstrate sensitivity to important structural features such as size and deformation of the nanostructures.

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Low-Energy Electron Diffraction Patterns Using Field-Emitted Electrons from Tungsten Tips

Cited by 21 publications

References 10 publications

STEM observation of tungsten tips sharpened by field-assisted oxygen etching

STEM observation of tungsten tips sharpened by field-assisted oxygen etching

Field Emission from W Tips Sharpened by Field-Assisted Nitrogen and Oxygen Etching

Theory of low-energy electron diffraction for detailed structural determination of nanomaterials: Ordered structures

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