The kinetics of formation and structure of an underlayer alloy: the Cu(100)-c(2×2)–Pd system

Barnes, Colin; AlShamaileh, Ehab; Pitkänen, Teemu; Kaukasoina, P.; Lindroos, M.

doi:10.1016/s0039-6028(01)01332-2

Cited by 25 publications

(23 citation statements)

References 38 publications

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“…4 along with that for CO-Cu(100) (top panel), which is shown for comparison. The spectrum for the CO-Cu(100) surface shows good agreement with results described in previous reports by Pope et al 35,36) and Barnes et al 37,38) Peaks around 185 K for the Cu(100) surface can thereby be ascribed to CO desorption from surface Cu atoms. With increasing Cr thickness, the desorption signal for CO-Cu shifts to higher temperature, accompanied by emergence of a signal at the high temperature side.…”

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confidence: 89%

Infrared Reflection Absorption Study for Carbon Monoxide Adsorption on Chromium Deposited Cu(100) Surfaces

et al. 2009

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This study investigates carbon monoxide (CO) adsorption and desorption behaviors on 0.1-0.6-nm-thick Cr-deposited Cu(100) surfaces using infrared reflection absorption (IRRAS) and temperature-programmed desorption (TPD) spectroscopic methods. The low-energy electron diffraction (LEED) pattern for the 0.1-nm-thick Cr-deposited Cu(100) surface indicates that distorted bcc-Cr(110) grows on fcc-Cu(100). The CO exposure to a clean Cu(100) at 90 K produces a single and sharp IR absorption band at 2090 cm À1 that is attributable to adsorbed CO on the on-top site of the Cu atoms' on the surface. Two absorption bands are located at 2085 and 2105 cm À1 on the IRRAS spectrum for the COsaturated 0.1-nm-thick Cr/Cu(110) surface. The former might originate from linearly bonded CO on the uncovered Cu substrate surface. With increasing Cr thickness, the latter high-frequency band becomes prominent. For the 0.3-nm-thick Cr surface, the band at 2117 cm À1 dominates all spectra through CO exposure. The TPD spectra of the Cr-deposited Cu surfaces show two remarkable features at 220-250 and 320-390 K, which are ascribable respectively to Cu-CO and Cr-CO bonds. Lower desorption peaks shift to higher temperatures with increasing Cr thickness. Based on TPD and IRRAS results, adsorption-desorption behaviors of CO on the Cr-deposited Cu(100) surfaces are discussed herein.

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confidence: 89%

Infrared Reflection Absorption Study for Carbon Monoxide Adsorption on Chromium Deposited Cu(100) Surfaces

et al. 2009

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“…We find the best agreement between the measured and computed IV curves when the Pd in each layer is located primarily in one 2 2 sublattice, in agreement with previous LEED analysis [7]. One significant difference between conventional LEED and LEEM is that the electron energy in LEEM is typically much lower.…”

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confidence: 87%

Origins of Nanoscale Heterogeneity in Ultrathin Films

et al. 2006

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A key challenge in thin-film growth is controlling structure and composition at the atomic scale. We have used spatially resolved electron scattering to measure how the three-dimensional composition profile of an alloy film evolves with time at the nanometer length scale. We show that heterogeneity during the growth of Pd on Cu(001) arises naturally from a generic step-overgrowth mechanism relevant in many growth systems.

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“…1 (a), the alloy consists of a c(2 × 2)-ordered Pd-Cu underlayer covered by a relatively pure layer of Cu. 13 Near step edges, some Pd is also present in the third atomic layer, as shown in Fig. 1 (b).…”

Section: Experiments a Methods And Materialsmentioning

confidence: 88%

“…We prepare the Cu(001)-c(2 × 2)-Pd buried surface alloy by depositing Pd (5 ML/hour) from an e-beam heated wire source onto the sample held at 210 • C. The structure, and growth, of the c(2 × 2)-Pd alloy are well understood. [10][11][12][13][14][15]20 The buried alloy forms when submonolayer coverages of Pd are deposited on Cu(001) at T> 150 • C. On terraces, Fig. 1 (a), the alloy consists of a c(2 × 2)-ordered Pd-Cu underlayer covered by a relatively pure layer of Cu.…”

Section: Experiments a Methods And Materialsmentioning

confidence: 99%

“…9 In the Cu(001)-c(2×2)-Pd buried surface alloy system, the Pd alloy is covered by a nearly pure layer of copper. [10][11][12][13][14][15] It is not evident that the buried Pd will have a significant influence on surface mass transport. In this work, we use Cu-adatom island-ripening measurements to show that Cu(001) surface diffusion is slowed by the presence of buried Pd atoms near the surface.…”

Section: Introductionmentioning

confidence: 99%

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Buried Pd slows self-diffusion on Cu(001)

et al. 2011

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Using low-energy electron microscopy, we determine that self-diffusion of the Cu(001) surface is slowed by the presence of a c(2 × 2)-Pd buried surface alloy. We probe surface diffusion using Cu-adatom island-ripening measurements. On alloyed surfaces, the island decay rate decreases monotonically as the Pd concentration is increased up to ∼ 0.5 ML, where the 2 × 2 buried alloy is Pd saturated. We propose that the Pd slows island ripening by inhibiting the diffusion of surface vacancies across terraces. For dilute alloys ( < ∼ 0.2 ML Pd), this conclusion is supported by densityfunctional theory calculations which show that surface vacancies migrate more slowly owing to an attraction to isolated buried Pd atoms. The results illustrate a fundamental mechanism by which even a dilute alloy thin-film coating may act to inhibit surface-diffusion-mediated processes, such as electromigration.

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The kinetics of formation and structure of an underlayer alloy: the Cu(100)-c(2×2)–Pd system

Cited by 25 publications

References 38 publications

Infrared Reflection Absorption Study for Carbon Monoxide Adsorption on Chromium Deposited Cu(100) Surfaces

Infrared Reflection Absorption Study for Carbon Monoxide Adsorption on Chromium Deposited Cu(100) Surfaces

Origins of Nanoscale Heterogeneity in Ultrathin Films

Buried Pd slows self-diffusion on Cu(001)

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