Photoemission study of the bulk and surface electronic structure of single crystals of gold

Hansson, G. V.; Flodström, S. A.

doi:10.1103/physrevb.18.1572

Cited by 183 publications

(83 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Table I lists the calculated work functions. The work functions of the clean Au and Ag surfaces agree with the experimental values [25,26], but that of Pt is ∼ 0.3 eV too low [27]. The latter can be attributed to the GGA functional.…”

supporting

confidence: 78%

Work functions of self-assembled monolayers on metal surfaces by first-principles calculations

2006

View full text Add to dashboard Cite

Using first-principles calculations we show that the work function of noble metals can be decreased or increased by up to 2 eV upon the adsorption of self-assembled monolayers of organic molecules. We identify the contributions to these changes for several (fluorinated) thiolate molecules adsorbed on Ag(111), Au(111) and Pt(111) surfaces. The work function of the clean metal surfaces increases in this order, but adsorption of the monolayers reverses the order completely. Bonds between the thiolate molecules and the metal surfaces generate an interface dipole, whose size is a function of the metal, but it is relatively independent of the molecules. The molecular and bond dipoles can then be added to determine the overall work function. PACS numbers: 73.30.+y, Recent advances in molecular electronics, where organic molecules constitute active materials in electronic devices, have created a large interest in metal organic interfaces [1]. Transport of charge carriers across the interfaces between metal electrodes and the organic material often determines the performance of a device [2]. Organic semiconductors differ from inorganic ones as they are composed of molecules and intermolecular forces are relatively weak. In a bulk material this increases the importance of electron-phonon and electron-electron interactions [3]. At a metal organic interface the energy barrier for charge carrier injection into the organic material is often determined by the formation of an interface dipole localized at the first molecular layer. The interface dipole can be extracted by monitoring the change in the metal surface work function after deposition of an organic layer [1,4].Atoms and molecules that are physisorbed on a metal surface usually decrease the work function, as the Pauli repulsion between the molecular and surface electrons decreases the surface dipole [5,6]. Chemisorption can give an increase or a decrease of the work function, and can even lead to counterintuitive results [7,8]. Selfassembled monolayers (SAMs) are exemplary systems to study the effect of chemisorbed organic molecules upon metal work functions [9]. More specifically, alkyl thiolate (C n H 2n+1 S) SAMs on the gold (111) surface are among the most extensively studied systems [10,11,12,13,14]. The sulphur atoms of the thiolate molecules form stable bonds to the gold surface and their alkyl tails are close packed, which results in a well ordered monolayer. SAMs with similar structures are formed by alkyl thiolates on a range of other (noble) metal surfaces [10,14,15].Often the change in work function upon adsorption of a SAM is interpreted mainly in terms of the dipole moments of the individual thiolate molecules, whereas only a minor role is attributed to the change induced by chemisorption [9,11,12]. This assumption turns out to be reasonable for adsorption of methyl thiolate (CH 3 S) on Au(111) [13], but for CH 3 S on Cu(111) it is not [14]. In this paper we apply first-principles calculations to study the interface dipoles and the work function change ...

show abstract

supporting

confidence: 78%

Work functions of self-assembled monolayers on metal surfaces by first-principles calculations

2006

View full text Add to dashboard Cite

show abstract

“…[42][43][44][45] Differences between crystallographic orientation of individual grains of the nanowire can create abrupt changes in the Fermi energy surface while crossing the grain boundaries, even though the overall variation of work function for gold is modest for different crystallographic orientations. 46 The electron mean free path in thin metal films is strongly constrained by the film thickness and therefore the details of surface scattering will also affect the thermoelectric properties of thin metal films. [47][48][49] We have taken the model developed previously to infer the temperature profile of ∆T along the short nanowire, 30 and we have updated it to account for the specific longer nanowire geometry of the present experiments.…”

Section: Resultsmentioning

confidence: 99%

Substantial local variation of the Seebeck coefficient in gold nanowires

2017

View full text Add to dashboard Cite

Nanoscale structuring holds promise to improve thermoelectric properties of materials for energy conversion and photodetection. We report a study of the spatial distribution of the photothermoelectric voltage in thin-film nanowire devices fabricated from single metal. A focused laser beam is used to locally heat the metal nanostructure via a combination of direct absorption and excitation of a plasmon resonance in Au devices. As seen previously, in nanowires shorter than the spot size of the laser, we observe a thermoelectric voltage distribution that is consistent with the local Seebeck coefficient being spatially dependent on the width of the nanostructure. In longer structures, we observe extreme variability of the net thermoelectric voltage as the laser spot is scanned along the length of the nanowire.The sign and magnitude of the thermoelectric voltage is sensitive to the structural defects, metal grain structure, and surface passivation of the nanowire. This finding opens the possibility of improved local control of the thermoelectric properties at the nanoscale.

show abstract

“…The calculated lattice constants, cohesive energies, surface energies, work functions, and related theoretical [28][29][30][31] and experimental [32][33][34][35]15 reference data from other groups are listed in Table I.…”

Section: Resultsmentioning

confidence: 99%

First-principles studies of Au(100)-hex reconstruction in an electrochemical environment

Feng¹,

Bohnen²,

Chan³

2005

Phys. Rev. B

View full text Add to dashboard Cite

Surface energies of Au͑100͒ p͑1 ϫ 1͒ and Au͑100͒-hex as modeled by a p͑1 ϫ 5͒ unit cell have been calculated as a function of surface charge by the density functional method. When the surface is neutral, the surface energy of Au͑100͒-hex is lower than that of Au͑100͒, consistent with the experimental observation that a Au͑100͒ surface has a hexagonal, instead of a square top layer. Calculations show that the surface energies of both systems increase when the surfaces are positively charged and there is a crossover with increasing charge so that the Au͑100͒-square becomes the ground state. This suggests that the surface-to-hexagonal reconstruction observed in this material can be reversed by an external field or surface charging. The required electric field is quite large, but is achievable at metal/electrolyte interfaces. In this paper, we analyze metal/ electrolyte interfacial energies and metal surface energies, discuss the possible role of specific adsorption, and compare our results to experiments by converting the calculated surface energies from surface-charge-density dependent to electrode-potential dependent, based on the relationship of the work function and potential of zero charge. Experimental results can be explained to some extent.

show abstract

Photoemission study of the bulk and surface electronic structure of single crystals of gold

Cited by 183 publications

References 32 publications

Work functions of self-assembled monolayers on metal surfaces by first-principles calculations

Work functions of self-assembled monolayers on metal surfaces by first-principles calculations

Substantial local variation of the Seebeck coefficient in gold nanowires

First-principles studies of Au(100)-hex reconstruction in an electrochemical environment

Contact Info

Product

Resources

About