STM study of room temperature adsorption of Au on the Si(111)(7×7) surface: evidence for the reaction of Au atoms with Si rest atoms

Chizhov, I.; Lee, G.; Willis, R.F.

doi:10.1007/s003390051284

Cited by 9 publications

(8 citation statements)

References 14 publications

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“…However, from previous experimental studies the adsorption sites and the nature of the bonds between these metallic atoms and Si111-7 7 surface remain elusive [5][6][7][8][9]. Scanning tunneling microscopy (STM) is a powerful tool in surface study.…”

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confidence: 99%

“…While it is often used to observe the adsorption of metallic atoms, the identification of adsorption sites remains nontrivial since STM only measures the local density of states near the Fermi level rather than the metallic atoms themselves [10]. Previous STM studies showed that at low coverage both Ag and Au form similar triangular patterns on Si111-7 7 at room temperature [6][7][8][9]. While the triangular STM image for Ag was identified as due to a single Ag atom by correlating to the quantitative Ag dosage [6,7], the triangular STM image for Au was speculated as due to a cluster of three Au atoms, each adsorbing at a rest Si atom site within the half unit cell [9].…”

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confidence: 99%

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Experimental and Theoretical Investigation of Single Cu, Ag, and Au Atoms Adsorbed onSi(111)−(7×7)

et al. 2005

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Using scanning tunneling microscopy and first principles calculations, the adsorption sites of single Cu, Ag, and Au atoms on the Si111-7 7 surface have been systematically investigated and identified. Despite their monovalence, these atoms were found to adsorb at high coordination sites, seeking to saturate the maximum number of dangling bonds. The stable adsorption sites were further observed to be distinctly different in the faulted and unfaulted half unit cells, showing an asymmetry that has never been observed for many other adsorbates.

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confidence: 99%

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confidence: 99%

Experimental and Theoretical Investigation of Single Cu, Ag, and Au Atoms Adsorbed onSi(111)−(7×7)

et al. 2005

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“…Quite unexpectedly, when there is just one single Au, Ag, or Cu atom occupying the faulted half unit cell, the STM images show up as six bright (brighter than Si adatoms) spots that form a triangle. Previously, these triangular patterns were often assigned as clusters formed by three or six atoms [21,22]; our STM images taken at low temperature (LT) [ Fig. 2(d)] clearly show that only a single bright spot remains in the faulted half unit cell after cooling to 77 K. This change in STM images between RT and LT is found reversible, indicating that the six bright spots at RT is a result of frequent hopping of an atom among different adsorption sites.…”

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confidence: 99%

Time-Dependent Tunneling Spectroscopy for Studying Surface Diffusion Confined in Nanostructures

et al. 2005

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By confining a diffusion atom in a nanometer region using surface potential heterogeneity, we have successfully employed a time-dependent tunneling spectroscopy to quantitatively study its random motion. A hopping rate in the range of 1-10 4 Hz, 3 orders of magnitude faster than those accessible by the existing diffusion methods based on scanning tunneling microscopy, was demonstrated for single Cu atoms diffusing in the faulted half unit cell of Si111-7 7. Our technique is potentially useful to detect fast diffusion processes such as H quantum diffusion at atomic scale. DOI: 10.1103/PhysRevLett.94.036103 PACS numbers: 68.35.Fx, 68.35.Md, 68.37.Ef, 68.47.Fg Surface diffusion is an important subject of study in physics, chemistry, biology, and materials science. It plays a vital role in chemical and surface catalytic reactions, selfassembly, crystal growth, and thin film epitaxy [1][2][3][4][5]. Observation and understanding of surface diffusion phenomenon in the past largely depend on the development of techniques [1,4]. Among the techniques, scanning tunneling microscopy (STM) [6] is advantageous in directly providing the atomistic mechanisms of diffusion [3][4][5][7][8][9][10] but is severely limited to slow diffusion rates from 10 ÿ19 to 10 ÿ14 cm 2 =s, as compared to the wide range from 10 ÿ19 to 10 ÿ5 cm 2 =s covered by the collection of different techniques [4]. Thus, processes in quantum diffusion of light atoms and in many other systems of practical interest with fast diffusion rates remain inaccessible by the STM technique.Limited by the electronic feedback loop response, the diffusion rate that can be probed by the widely used frameby-frame imaging [11] and atom-tracking [12] methods is in the slow regime. In atom tracking for which no full frame imaging is required, the fastest measurable hopping rate is about 10 Hz. With a state-of-art design [7,9,10], STM imaging can now be performed at a rate of 10 frame=s, again leading to observation of a maximum hopping rate of only 10 Hz (equivalent to 10 ÿ14 cm 2 =s for nearest neighbor site hopping). Using a new concept of measuring diffusion by the bypass of the feedback loop, we demonstrate in this Letter a new STM-based method that can expand the range by at least 3 orders of magnitude faster, to a hopping rate on the order of 10 4 Hz (equivalent to 10 ÿ11 cm 2 =s). Further expansion of our method will become possible if faster preamplifier and data acquisition systems are used. This leads to significant overlaps in measurable diffusion rates with other techniques while retaining the atomic resolution. The extension will not only enable STM study of diffusion in the fast regime to facilitate direct comparison with results obtained by other techniques, but also enable the study of processes such as H quantum diffusion for which cooling never slows it down [1]. As shown by Gomer and his co-workers with field emission microscopy, the H quantum diffusion measured for a large number of systems [13][14][15][16] falls in the range of 10 ÿ13 to 10 ÿ10 cm 2 =s...

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“…24 However, from previous experimental studies the adsorption sites and the nature of the bonds between these metallic atoms and the Si(111)-7 × 7 surface remain elusive. [25][26][27][28] Our results indicate that the dangling bonds at Si rest atom and the Si adatom, either at the corner or at the centre, are not the perfect adsorption sites for Au 1 and Ag because their adsorption energies are higher than those on the high coordination sites. The above results can be directly compared to a recent first principles study by Cho and Kaxiras 21 22 for K, Mg, Ga, Si and Ge, using a (4 × 4) supercell rather than a full (7 × 7) cell.…”

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confidence: 94%

Initial Stages of Ag Adsorption on Si(111)-7 × 7 Surface

Lin¹,

Zhou²,

Li³

et al. 2010

Jnl of Comp & Theo Nano

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Initial stages of Ag atoms adsorption on Si(111)-7 × 7 surface were studied by first-principles calculations. The results showed that the most stable adsorption position for a single Ag atom is at S sites, which are almost in the middle between H 3 and B 2 high coordination sites. When two single Ag atoms are adsorbed on a Si half unit cell, they prefer to adsorb on the two closest S sites and form weak Ag-Ag bond.

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STM study of room temperature adsorption of Au on the Si(111)(7×7) surface: evidence for the reaction of Au atoms with Si rest atoms

Cited by 9 publications

References 14 publications

Experimental and Theoretical Investigation of Single Cu, Ag, and Au Atoms Adsorbed onSi(111)−(7×7)

Experimental and Theoretical Investigation of Single Cu, Ag, and Au Atoms Adsorbed onSi(111)−(7×7)

Time-Dependent Tunneling Spectroscopy for Studying Surface Diffusion Confined in Nanostructures

Initial Stages of Ag Adsorption on Si(111)-7 × 7 Surface

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