Formation of patchy surface overlayers: Alkali adsorption and alkali carbon monoxide and oxygen coadsorption on Ru(0001) and Ru(10�10)

Surnev, S.; Кискинова, М.

doi:10.1007/bf01141599

Cited by 2 publications

(5 citation statements)

References 21 publications

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“…Before the discussion of the relationship between the oxygen coverage and the work function, or the electron affinity (EA), a detailed examination of the SE edge is necessary. In fact, its shape can give hints on surface work function inhomogeneity. , The raw SE edge intensity is plotted against the KE in Figure (a), for various values of N O ( N O = 0, 0.25, 0.5). We observe that the SE cutoff KE decreases with increasing N O : the work function of the water-covered surface is lower by 0.38 eV than that of the clean one.…”

Section: Resultsmentioning

confidence: 99%

“…Finally we measured the variations of the work function and electron affinity as a function of coverage, a method typically used to follow adsorption and deposition processes with high surface sensitivity. Work function changes are sensitive to the growth mode (uniform versus island growth) and to conformational changes of the adsorbate . Finally, we provide the electron affinity of the modified Si(001) surface at water saturation.…”

Section: Introductionmentioning

confidence: 99%

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Real-Time X-ray Photoemission Spectroscopy Study of Si(001)-2×1 Exposed to Water Vapor: Adsorption Kinetics, Fermi Level Positioning, and Electron Affinity Variations

et al. 2016

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The great advantage of X-ray photoemission spectroscopy, when performed in real time, e.g., during the reaction of a gas with a surface, is the possibility of monitoring in a single experiment both the chemical aspects (adsorption kinetics, bond formation) and the physical ones (Fermi level positioning, variations in the electron affinity). In the present study we examine the reaction of water with Si(001)-2×1 at room temperature in real time not only because water, ubiquitous in (ultra) high-vacuum systems, is the main source of surface defects controlling the surface Fermi level, but also because water-saturated silicon may become an interesting starting surface in the atomic layer deposition of dielectrics on silicon. The question of water adsorption on silicon Si(001)-2×1 is renewed under the following four perspectives: (1) We propose an original kinetic analysis of the water uptake using an integrated form of the precursor model differential equations, underlying a dependence on pressure. (2) We perform a thorough analysis of the Fermi positioning within the band gap due to water-related surface defects as a function of water coverage and for four different doping types and levels. (3) We follow the changes in the surface dipole as a function of coverage, with considerations of the dissociation channels. (4) Using seven different n and p doping levels, we extract the electron affinity at saturation, a useful parameter to know if heterostructures are built upon the water-covered surface. In addition to an applicative view, the present data can be a benchmark for theoretical calculations such as molecular dynamics, surface defect energy, and work function calculations.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Real-Time X-ray Photoemission Spectroscopy Study of Si(001)-2×1 Exposed to Water Vapor: Adsorption Kinetics, Fermi Level Positioning, and Electron Affinity Variations

et al. 2016

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“…A good test of surface uniformity is the time evolution of the secondary electron energy spectrum: If the energy spectrum just shifts along energy axis without changing the shape, the surface probably keeps uniformity during the adsorption/ deposition experiment. 28 Since this is usually not the case, the interpretation of the onset shift should depend on the measurement regime.…”

Section: A Measurement Of the Dipole Moment And The Polarizabilitymentioning

confidence: 99%

“…Introducing more complicated models to describe the experimental results did not yield in satisfactory results as well. The problem in some systems can be due to the surface non-uniformity, as in the case of potassium adsorption on Ru(1010): 28 As we already discussed, if the dipoles do not form 2D islands but are still not uniformly distributed, only l could be correctly determined.…”

Section: A Measurement Of the Dipole Moment And The Polarizabilitymentioning

confidence: 99%

“…Although known for a long time and studied in the case of the work function measurements using the diode method 28 and recently in the field emission experiments, 29 to the best of our knowledge, the effect of a patch field on the onset method has not yet been considered. Apparently, the problem is trivial: Since the electrons are detected far from the surface, the onset position should correspond to the surface averaged work function hUi (cf.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the patch field on work function measurements based on the secondary electron emission

Bundaleski

Trigueiro

Silva

et al. 2013

Journal of Applied Physics

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A work function study based on the onset shift (i.e., following low energy cutoff) of secondary electron spectra has been used for the last four decades to monitor the deposition and adsorption in real time, measure the dipole momentum and polarizability of the surface layer, and determine the lateral distribution of the work function. In this work, we show that the onset shift depends on both the coverage of adsorbed species that change the work function and the size of low work function patches. Additionally, the extraction field, which is always applied in these measurements, may also influence the onset shift. Numerical calculations of the potential distributions above different non-uniform surfaces were performed in order to quantitatively determine each of these influences. Depending on the patch size, we define three measurement regimes in which the onset position is related to either the surface average of the work function (small patches), the minimum local work function (large patches), or a value in-between (intermediate size patches). Experimental data have corroborated these findings and demonstrated that manipulating the extraction field intensity enables transition between the measurement regimes. Typical misinterpretations due to neglecting the patch size contribution and the surface non-uniformity to the onset shift are analyzed. Additionally, possible application of work function study for determination of the growth mode in the case of submonolayer deposition was discussed. V

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Formation of patchy surface overlayers: Alkali adsorption and alkali carbon monoxide and oxygen coadsorption on Ru(0001) and Ru(10�10)

Cited by 2 publications

References 21 publications

Real-Time X-ray Photoemission Spectroscopy Study of Si(001)-2×1 Exposed to Water Vapor: Adsorption Kinetics, Fermi Level Positioning, and Electron Affinity Variations

Real-Time X-ray Photoemission Spectroscopy Study of Si(001)-2×1 Exposed to Water Vapor: Adsorption Kinetics, Fermi Level Positioning, and Electron Affinity Variations

Influence of the patch field on work function measurements based on the secondary electron emission

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