Faceting induced by ultrathin metal films: structure, electronic properties and reactivity

Madey, Theodore E.; Nien, C.-H.; Pelhos, K.; Kołodziej, Jacek; Abdelrehim, Ihab M.; Tao, H.-S.

doi:10.1016/s0039-6028(99)00570-1

Cited by 105 publications

(80 citation statements)

References 33 publications

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“…Madey, et al pointed out that a proper coverage (∼ 1 physical monolayer, PML) of a noble metal film on the W(111) surface is one of the prerequisites in inducing the faceting transition [6][7][8][9][10][11]. However, it is very difficult to control the coverage to exactly 1 PML due to the rather high deposition rate.…”

Section: A Atomic Structure Of Single-atom Tipsmentioning

confidence: 99%

“…The thermodynamic driving force for the formation of this single-atom tip is the faceting process for Pd on W(111). It has been known that ultrathin Pd, Pt, Au, Ir, or Rh films grown on the W(111) surface can form three-sided pyramids with {211} facets upon annealing in UHV [6][7][8][9][10][11]. The success of the Pd-covered W single-atom tip implies that other noble metals (such as Pt, Ir, Rh, and Au) covered W (111) tips may also form single-atom tips through a similar procedure.…”

Section: Introductionmentioning

confidence: 99%

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Preparation of Single-Atom Tips and Their Field Emission Behaviors

Kuo

Hwang

et al. 2006

e-J. Surf. Sci. Nanotechnol.

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We have developed a simple and reliable method for preparing single-atom tips. Electrochemical techniques are applied to deposit a noble metal film on the W < 111 > tip. With the protection of the metal film, the tip can be stored and transferred in the ambient condition. After a gentle annealing of the plated tip in vacuum, a thermally and chemically stable nano-pyramid with single atom sharpness can be generated at the tip apex. The atomic structure of the tip is imaged by a field ion microscope (FIM) layer by layer through field evaporation. The corresponding field emission patterns can also be determined by the field emission microscopy (FEM). Most importantly, the single atom sharpness as well as the pyramidal structure can be regenerated for tens of times in vacuum simply by annealing if the apex is accidentally damaged. Field emission measurements indicate that the single-atom tips can emit stable electron beams of high brightness with a small extension angle. These desirable features make the single-atom tips very promising for future applications.

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Section: A Atomic Structure Of Single-atom Tipsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Preparation of Single-Atom Tips and Their Field Emission Behaviors

Kuo

Hwang

et al. 2006

e-J. Surf. Sci. Nanotechnol.

View full text Add to dashboard Cite

show abstract

“…In the 1990s, Madey and coworkers have found that an ultrathin Pd, Pt, Au, Ir or Rh film grown on a flat W(111) surface can undergo massive reconstruction upon annealing to form three-sided pyramids with {211} facets (21)(22)(23)(24). The driving force of the facet formation was attributed to an increase in surface energy anisotropy as the metal films were adsorbed on the W(111) surface, which was later confirmed by theoretical calculations (25,26).…”

Section: Noble-metal Covered W(111) Single-atom Tips 1 Adsorbatmentioning

confidence: 99%

Noble-Metal Covered W(111) Single-Atom Electron Sources

et al. 2009

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Single-atom tips can be used as ideal point sources of electron beams. It has been shown that noble-metal covered W(111) singleatom tips can be reliably prepared and their lifetimes are long enough for real applications. These tips are both thermally and chemically stable, and can be regenerated in vacuum when accidentally damaged or contaminated. The atomic stacking remains the same each time it is regenerated. The small opening angle, smallest emitting area, high brightness, high spatial coherence, and high stability of these single-atom electron sources make them highly desirable for many applications. Both the brightness and spatial coherency of these electron sources are orders of magnitude better than those of the state-of-the-art electron sources used in electron microscopes. Application of these sources may significantly improve the performance and expand the capabilities of current electron microscopes, and open up many new possibilities in electron-beam based techniques.

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“…The single-atom electron sources are prepared by heating noble-metal-covered W<111> tips in ultra high vacuum (UHV). Since the surface energy of the {211} faces are extremely decreased by monolayer coverage of noble metals, the anisotropy of surface energy generates spontaneously the faceting structure at elevated temperatures; the areas of the stable {211} faces extend on the W surface, and nano-pyramids with three {211} faceting faces grew on the (111) faces [6][7][8].…”

Section: Introductionmentioning

confidence: 99%