Field Emission Microscopy Study of Au-Covered Nanopyramids with 211-Facet Sides Grown on Blunt W Tips via Assistive Remolding Treatment

Rokuta, Eiji; Nakagawa, Tatsuhiro; Murata, Hidekazu; Fujita, Shozo; Shimoyama, Hiroshi; Oshima, C.

doi:10.1143/jjap.50.115001

Cited by 3 publications

(12 citation statements)

References 22 publications

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“…This could be due to a strong local enhancement due to the atomic level sharpness of the top of the pyramid. [16][17][18] As can be seen in Fig. 4(e), the simulations did not confirm this hypothesis.…”

confidence: 79%

“…15 Various well-established methods have been used to fabricate nano-tips. 1-4, [16][17][18][19] Typically, a nano-tip is grown on a larger metallic tip by applying strong DC fields, 2-4, [16][17][18] depositing metal. 1,4 Fabrication of a nano-tip in situ for laser-induced electron pulse applications is, however, not a simple task because of the presence of optical elements used in the laser focusing system which must remain very clean.…”

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confidence: 99%

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Laser-induced asymmetric faceting and growth of a nano-protrusion on a tungsten tip

et al. 2016

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Irradiation of a sharp tungsten tip by a femtosecond laser and exposed to a strong DC electric field led to gradual and reproducible surface modifications. By a combination of field emission microscopy and scanning electron microscopy, we observed asymmetric surface faceting with sub-ten nanometer high steps. The presence of well pronounced faceted features mainly on the laser-exposed side implies that the surface modification was driven by a laser-induced transient temperature rise -on a scale of a couple of picoseconds -in the tungsten tip apex. Moreover, we identified the formation of a nano-tip a few nanometers high located at one of the corners of a faceted plateau. The results of simulations emulating the experimental conditions, are consistent with the experimental observations. The presented conditions can be used as a new method to fabricate nano-tips of few nm height, which can be used in coherent electron pulses generation. Besides the direct practical application, the results also provide insight into the microscopic mechanisms of light-matter interaction. The apparent growth mechanism of the features may also help to explain the origin of enhanced electron field emission, which leads to vacuum arcs, in high electric-field devices such as radio-frequency particle accelerators.A metallic nano-tip with sharpness of a few nanometers can provide very bright and spatially coherent electron waves. [1][2][3][4][5] This is highly beneficial in many applications such as electron diffraction, microscopy, and holography. [6][7][8] During irradiation by laser pulses a nanotip is also expected to generate pulsed electron waves with high brightness and coherence. [9][10][11][12][13] Such electron pulses enable experiments with high temporal and spatial resolution for investigations of ultrafast phenomena in solids. 14 A higher-performance pulsed electron source could make a significant contribution to future investigations of the dynamics in ultrafast devices. 15 So far various well-established methods have been used to fabricate nano-tips. [1][2][3][4][16][17][18] Typically, a nano-tip is grown on a larger metallic tip by applying strong DC fields, [2][3][4][16][17][18] heating 3,16-18 or depositing metal. 1,4 Fabrication of a nano-tip in situ for laser-induced elec-

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confidence: 79%

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confidence: 99%

Laser-induced asymmetric faceting and growth of a nano-protrusion on a tungsten tip

et al. 2016

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“…• and stepwise fluctuations in the stability characteristics of the field emission current [8]. These findings were an indirect implication of formation of the nanopyramids.…”

Section: Introductionmentioning

confidence: 87%

“…In order to make the sharp tip blunt, the tip was heated at 2000 K. The remolding treatment was undertaken by elevating the tip temperature and by simultaneously applying negative voltages to the extractor electrode while grounding the tip. In this study, 2000 K and 4.0 kV were used as a combination of the remolding temperature and voltage that appropriately lead to a formation of so-called "{211}-faceted end", which is a protruded end produced by marked faceting of three {211} planes around the centered (111) plane [8]. We grew the nanopyramids on this {211}-faceted end by using typical procedures described elsewhere [3].…”

Section: Methodsmentioning

confidence: 99%

“…1(c)], bright spots attributable to Pd atoms were merely added to the preceding FIM one. Coverage was not unambiguous, but estimated to be approximately monolayer from a change in slopes of the Fowler-Nordheim plots [8]. Then, the Pddeposited tip was annealed at 1000 K, which yielded the nanopyramid growth for the ultrasharp end.…”

Section: A Fabrication Of Nanopyramid On Blunt Tipmentioning

confidence: 99%

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Field Ion Microscopy of Nanometer-Size Pyramid Grown on a Blunt End of Tungsten Tip

Nakagawa

Rokuta

Murata

et al. 2012

e-J. Surf. Sci. Nanotechnol.

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We fabricated nanometer-size pyramids with three {211} -facet sides (nanopyramids) on blunt W tip and observed their atomic structures by field ion microscopy (FIM). The blunt W tip was preliminary subjected to remolding treatment in order to sharpen its end. Owing to the atomic resolution of FIM, we found that the {211} and {110} planes faceted markedly as a result of the remolding treatment and clearly detected the neighboring {211} and {110} planes were separated by a monoatomic chain along the ⟨111⟩ direction. In addition, the (111) plane was raised and narrowed owing to the faceting of the three surrounding {211} planes. Dimension of the narrowed (111) plane was about 3 nm. By using the surface of the remolded-tip end as a substrate, we grew the nanopyramid by depositing Pd atoms and elevating the sample temperature to 1000 K. The FIM observation indicated typical signs for the nanopyramid growth such as markedly-faceted {211} planes, monoatomic linear chains for the pyramid ridge, and extremely narrow top of the pyramid. In this study, the top was the third layer of the ideal nanopyramid counting from the top. Along with previous field emission data [E. Rokuta, T. Nakagawa, H. Murata, S. Fujita, H. Shimoyama, and C. Oshima, Jpn. J. Appl. Phys. 50, 115001 (2011).], the remolding treatment was proven to be useful for the nanopyramid growth on the blunt end of the W tip.

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Fabrication of Pt- and Au-coated W Nano Tip with Electroplated Films as a Noble-metal Source toward Viable Application for Long-life Electron Source

Asai

Tanaka

Murata

et al. 2021

e-J. Surf. Sci. Nanotechnol.

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The surface diffusion method was used to produce tungsten (W) nanopyramids coated with monolayer films of platinum (Pt) and gold (Au). Although the general structures of the nanopyramids were the same, the top of the nanopyramids was different from the Pt and Au cases, i.e., a monomer was observed for Pt, whereas a trimer observed for Au. The effects of simultaneous heating and the electric field on the structural evolution of nanopyramids were also studied. We observed that the broken nanopyramids were rapidly regenerated by heating in an electric field. The opening angles of field-emitted electrons were found to be approximately ±2° and ±2.5° for Pt and Au, respectively. From the obtained results, it was observed that the field-emission properties of all specimens were almost the same.

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Field Emission Microscopy Study of Au-Covered Nanopyramids with 211-Facet Sides Grown on Blunt W Tips via Assistive Remolding Treatment

Cited by 3 publications

References 22 publications

Laser-induced asymmetric faceting and growth of a nano-protrusion on a tungsten tip

Laser-induced asymmetric faceting and growth of a nano-protrusion on a tungsten tip

Field Ion Microscopy of Nanometer-Size Pyramid Grown on a Blunt End of Tungsten Tip

Fabrication of Pt- and Au-coated W Nano Tip with Electroplated Films as a Noble-metal Source toward Viable Application for Long-life Electron Source

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