Nucleation and growth of thin metal films on clean and modified metal substrates studied by scanning tunneling microscopy

Hwang, R. Q.; Günther, C.; Schröder, J.; Günther, Sebastian; Kopatzki, E.; Behm, R. J.

doi:10.1116/1.578012

Cited by 102 publications

(47 citation statements)

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“…In a simple picture, these coadsorbates should increase the diffusion barrier by geometric blocking of neighboring sites, as often observed in studies under UHV conditions. [20] Third, in hopping between neighboring adsorption sites on the bare Cu(100) surface, the adsorbate only has to traverse bridge sites of the Cu substrate. In contrast, jumps between c(22) lattice sites require that the adsorbate crosses over an energetically unfavorable top site or performs two successive jumps across bridge sites.…”

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confidence: 99%

In Situ Video‐STM Studies of Adsorbate Dynamics at Electrochemical Interfaces

2010

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The dynamic behavior of individual adsorbates at electrochemical interfaces was studied directly by in situ high-speed scanning tunneling microscopy, using sulfur adsorbed on Cu(100) electrodes in 0.01 M HCl solution as an example. By dosing from diluted Na(2)S solutions S(ad) coverages of a few percent can be prepared, with the sulfur adsorbates occupying positions within the c(2x2) lattice of coadsorbed chloride. S(ad) tracer diffusion occurs via hopping between neighboring c(2x2) lattice sites at considerably higher rates than those of sulfur on Cu(100) under UHV conditions, indicating a pronounced influence of the electrochemical environment on the adsorbate surface dynamics. The diffusion barrier linearly increases by 0.5 eV per V with potential and is strongly affected by neighboring S(ad) and surface defects. The S(ad)-S(ad) interactions extend over approximately 7 A. They are repulsive between nearest-neighbor and attractive between next-nearest-neighbor sites, respectively, and result in significantly reduced diffusion barriers. S(ad) on the upper terrace side of steps are transiently trapped and exhibit lower diffusion rates, leading to the formation of small metastable p(2x2) domains. Attractive interactions between S(ad) and domain boundaries in the c(2x2) adlayer result in boundary pinning as well as transient trapping and enhanced diffusion of S(ad) along the boundary.

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confidence: 99%

In Situ Video‐STM Studies of Adsorbate Dynamics at Electrochemical Interfaces

2010

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“…Surface adsorbates, or "additives," can profoundly change both the dynamics of mass transport and the equilibrium morphology. These effects of adsorbates have been revealed by studies of surface faceting and step bunching, [1][2][3][4] film growth, [5][6][7][8][9][10][11][12][13] island shapes, 11 reconstruction, [14][15][16] coarsening, 17,18 step fluctuations, 19 and other phenomena.…”

Section: Introductionmentioning

confidence: 99%

Adsorbate-enhanced transport of metals on metal surfaces: Oxygen and sulfur on coinage metals

Thiel

Shen

Liu

et al. 2010

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Coarsening (i.e., ripening) of single-atom-high, metal homoepitaxial islands provides a useful window on the mechanism and kinetics of mass transport at metal surfaces. This article focuses on this type of coarsening on the surfaces of coinage metals (Cu, Ag, Au), both clean and with an adsorbed chalcogen (O, S) present. For the clean surfaces, three aspects are summarized: (1) the balance between the two major mechanisms-Ostwald ripening (the most commonly anticipated mechanism) and Smoluchowski ripening-and how that balance depends on island size; (2) the nature of the mass transport agents, which are metal adatoms in almost all known cases; and (3) the dependence of the ripening kinetics on surface crystallography. Ripening rates are in the order (110)>(111)>(100), a feature that can be rationalized in terms of the energetics of key processes. This discussion of behavior on the clean surfaces establishes a background for understanding why coarsening can be accelerated by adsorbates. Evidence that O and S accelerate mass transport on Ag, Cu, and Au surfaces is then reviewed. The most detailed information is available for two specific systems, S/Ag (111) and S/Cu(111). Here, metal-chalcogen clusters are clearly responsible for accelerated coarsening. This conclusion rests partly on deductive reasoning, partly on calculations of key energetic quantities for the clusters (compared with quantities for the clean surfaces), and partly on direct experimental observations. In these two systems, it appears that the adsorbate, S, must first decorate-and, in fact, saturate-the edges of metal islands and steps, and then build up at least slightly in coverage on the terraces before acceleration begins. Acceleration can occur at coverages as low as a few thousandths to a few hundredths of a monolayer. Despite the significant recent advances in our understanding of these systems, many open questions remain. Among them is the identification of the agents of mass transport on crystallographically different surfaces e.g., 111, 110, and 100. KeywordsAmes Laboratory, Materials Science and Engineering, Mathematics, Physics and Astronomy Disciplines Biological and Chemical Physics | Materials Science and Engineering | Mathematics | Physical Chemistry CommentsThe following article appeared in Journal of Vacuum Science and Technology A 28, no. 6 (2010) Coarsening ͑i.e., ripening͒ of single-atom-high, metal homoepitaxial islands provides a useful window on the mechanism and kinetics of mass transport at metal surfaces. This article focuses on this type of coarsening on the surfaces of coinage metals ͑Cu, Ag, Au͒, both clean and with an adsorbed chalcogen ͑O, S͒ present. For the clean surfaces, three aspects are summarized: ͑1͒ the balance between the two major mechanisms-Ostwald ripening ͑the most commonly anticipated mechanism͒ and Smoluchowski ripening-and how that balance depends on island size; ͑2͒ the nature of the mass transport agents, which are metal adatoms in almost all known cases; and ͑3͒ the dependence of the ripe...

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“…Such situation takes place during the formation of 2D islands in contrary to the adsorbate distributed uniformly. In reality, deposition of cobalt on Ru(0001) at RT leads to the growth of triangular-shaped 2D islands [2]. Figure 2 shows the results of the substrate (Ru) peak change during adsorption of cobalt as measured with SR-PS.…”

Section: Co 2p Transitionmentioning

confidence: 99%

“…The study of cobalt deposition on ruthenium is motivated by interest in thin magnetic film grown on a ruthenium substrate [1][2][3]. Taking into account that the lattice constant of Co and Ru is equal to 0.2506 and 0.2650 nm, respectively [4], the misfit, m, is calculated as m = −5.4% for the Co/Ru interface.…”

Section: Introductionmentioning

confidence: 99%

Photoemission Study of the Initial Growth of Co on Ru(0001)

et al. 2007

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The growth process of cobalt on Ru(0001) was characterized by photoelectron spectroscopy excited by X-ray and synchrotron radiation. The binding energy position and intensity of the Co 2p 3/2 and Ru 3d 5/2 core levels as well as the shape and structure of the valence band spectra corresponding to the different stages of the deposition were investigated. An observed small positive binding energy shift is a consequence of an increase in the cobalt adatoms coordination number. The core-level shift between bulk and surface Ru atoms is determined as −360 meV. Upon adsorption of cobalt, the interface peak appears with a shift of −(70 ÷ 80) meV relative to the bulk one. On the basis of unchanged energy positions and widths of the Ru-derived features of the valence band spectra, a weak interaction between cobalt and substrate is suggested. The measured valence band could be reproduced by superimposing the spectra of the pure elements.

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Nucleation and growth of thin metal films on clean and modified metal substrates studied by scanning tunneling microscopy

Cited by 102 publications

References 0 publications

In Situ Video‐STM Studies of Adsorbate Dynamics at Electrochemical Interfaces

In Situ Video‐STM Studies of Adsorbate Dynamics at Electrochemical Interfaces

Adsorbate-enhanced transport of metals on metal surfaces: Oxygen and sulfur on coinage metals

Photoemission Study of the Initial Growth of Co on Ru(0001)

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