Synchrotron-Induced Photoelectron Spectroscopy of Semiconductor/Electrolyte Model Interfaces:  Coadsorption of Br2 and H2O on WSe2(0001)

Mayer, Tobias; Pettenkofer, C.; Jaegermann, Wolfram

doi:10.1021/jp961116d

Cited by 10 publications

(2 citation statements)

References 54 publications

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“…Interestingly, the SSPV is removed with coadsorbed H 2 O and full band bending appears in the spectra. From a large number of experiments on differently doped samples we are able to relate substrate binding energies to the exact position of the surface Fermi level . The position of the substrate surface Fermi level in the course of Na adsorption and H 2 O coadsorption is displayed as SSPV in Figure .…”

Section: Resultsmentioning

confidence: 99%

“…From a large number of experiments on differently doped samples we are able to relate substrate binding energies to the exact position of the surface Fermi level. 21 The position of the substrate surface Fermi level in the course of Na adsorption and H 2 O coadsorption is displayed as SSPV in Figure 5. A correction of the SSPV by inspection of the measured Fermi level of the adsorbed Na clusters gives the surface Fermi level in thermodynamic equilibrium as also shown in Figure 5.…”

Section: Coadsorption Of H 2 O Onto Na Preadsorbed P-wse 2 (0001)mentioning

confidence: 99%

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A Photoemission Study of Solute−Solvent Interaction: Coadsorption of Na and H₂O on WSe₂(0001)

Mayer

Jaegermann

2000

J. Phys. Chem. B

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Semiconductor/electrolyte model interfaces are prepared in UHV by adsorbing and coadsorbing the electrolyte species Na and H2O onto chemically inert van der Waals (0001) surfaces of WSe2 at low temperatures (100K). The state of the adsorbed species is monitored by soft X-ray photoelectron spectroscopy (SXPS) and the surface potentials, i.e., band bending eV bb, surface photovoltage SPV, electron affinity χ, and work function Φ by SXPS and ultraviolet photoelectron spectroscopy (UPS). H2O coadsorbed to metallic Na clusters is dissociated and electron emission lines due to Na+ and OH- ions are observed. Coadsorption of Na to condensed ice layers preserves the H2O molecules. The 3s electrons of the adsorbed Na atoms are transferred to the p-WSe2 substrate as indicated by a depletion space charge layer on p-WSe2. With increasing exposition to SX radiation, the 2p emission of the Na+ ions is stepwise shifted to lower binding energy. We relate this successive shift to an increasing number of reorganized H2O molecules from the adsorbate layer in its ice configuration to the hydration shell of Na+.

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Section: Resultsmentioning

confidence: 99%

Section: Coadsorption Of H 2 O Onto Na Preadsorbed P-wse 2 (0001)mentioning

confidence: 99%

A Photoemission Study of Solute−Solvent Interaction: Coadsorption of Na and H₂O on WSe₂(0001)

Mayer

Jaegermann

2000

J. Phys. Chem. B

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UHV Model experiments of the semiconductor/electrolyte interface: Adsorption of I₂on n‐ and p‐doped WSe₂(0001)

Henrion¹,

Jaegermann

1998

Ber Bunsenges Phys Chem

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The WSQ (aoOl)/r, semiconductodelectrolyte interface was simulated in Ultra-high-Vacuum 0 by adsorbing 12 onto the van der Waals plane of the layered substrate at 100 K. The interface was characterized by photoelectron spectxuscopy and surface photovoltage measurements. The interaction proved to be non-reactive and 1, adsorbs as molecular species. The electric potential distributions measured by UPS und X P S are in reasonable agreement to semiconductodelectrolyte interfaces. Iodine behaves as electron acceptor inducing strong band bending only for ndoped and not for pdoped samples. After correcting for source-induced surface photovoltage effects the 2au level (LUMO) of adsorbed 12 is identified of being responsible for establishing electronic equilibrium.

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4.2 Electron work function of metals and semiconductors

Jakobi¹

2002

Landolt-Börnstein - Group III Condensed Matter

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If an electron beam is directed towards a surface, it gets reflected if its potential is equal to -(E P /e + ∆Φ), the negative value of the primary energy divided by e and corrected for ∆Φ between the surface and the electron emitter (in the widest sense: cathode, electron gun, etc.). Since the surface serves here as the anode in a diode configuration, the name diode method has been chosen. This method was introduced early by P.A. Anderson [35A]. Many details of different experimental set-ups are discussed in [73K2, 79H3]. It was pointed out [85K8] that for carefully chosen conditions and for a patchy surface, i.e., a surface consisting of a composite of smaller areas of different work function, the diode method measures the same arithmetical average of Φ as the Kelvin method (see below). How to use a HREEL spectrometer for the diode method is reported in Ref.[85S3]. Vibrating capacitor method (Kelvin)The vibrating capacitor method is based on the work of Lord Kelvin [1898K] and of Zisman [32Z]. A condensor is formed of the surface to be studied and a reference electrode in front of it which are connected by a ammeter and a variable voltage source. If the capacitance between the plates (sample and reference electrode) is changed, e.g., by changing their distance, a current will flow. By compensating the Ref. p. 4.2-118] 4.2 Electron work function of metals and semiconductors Lando lt-Börnstein New Series III/42A2 4.2-7contact potential difference through the voltage source, the current can be brought to zero. Since Φ of the surface is part of the contact potential, its changes relative to the reference electrode can be measured. A more extended description can be found in Ref. [79H3]. A very versatile instrument of this kind was developed by Besocke [76B]. Data collectionData have been collected for metal as well as semiconductor substrates. In the case of metals only elemental, single-crystalline samples were considered. There are a few exceptions to this general rule. Some metallic alloys are listed in case of single-crystalline samples of well defined (stoichiometric) composition. Some data are also incorporated for evaporated, mostly polycrystalline films of materials for which no single-crystal data are available. For semiconductor substrates, adsorbate-induced workfunction changes consist of two contributions: band-bending and electron-affinity changes. Systems were discarded for which the overall change in work function was small (<0.2 eV) or for which the authors did not report a separation of the two contributions. With respect to the adsorbates, only single-component adsorption layers were considered, i.e., co-adsorbates were omitted. Furthermore, it should be noted that completeness -although intended -could not be achieved. It was learned that work-function data are very often not in the center of a publication. Work-function data even seemed to many authors too marginal to give explicitly reference to them in the title, abstract or key words. Therefore, also computer based research could not guarant...

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Synchrotron-Induced Photoelectron Spectroscopy of Semiconductor/Electrolyte Model Interfaces: Coadsorption of Br₂ and H₂O on WSe₂(0001)

Cited by 10 publications

References 54 publications

A Photoemission Study of Solute−Solvent Interaction: Coadsorption of Na and H₂O on WSe₂(0001)

A Photoemission Study of Solute−Solvent Interaction: Coadsorption of Na and H₂O on WSe₂(0001)

UHV Model experiments of the semiconductor/electrolyte interface: Adsorption of I₂on n‐ and p‐doped WSe₂(0001)

4.2 Electron work function of metals and semiconductors

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Synchrotron-Induced Photoelectron Spectroscopy of Semiconductor/Electrolyte Model Interfaces: Coadsorption of Br2 and H2O on WSe2(0001)

Cited by 10 publications

References 54 publications

A Photoemission Study of Solute−Solvent Interaction: Coadsorption of Na and H2O on WSe2(0001)

A Photoemission Study of Solute−Solvent Interaction: Coadsorption of Na and H2O on WSe2(0001)

UHV Model experiments of the semiconductor/electrolyte interface: Adsorption of I2on n‐ and p‐doped WSe2(0001)

4.2 Electron work function of metals and semiconductors

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Synchrotron-Induced Photoelectron Spectroscopy of Semiconductor/Electrolyte Model Interfaces: Coadsorption of Br₂ and H₂O on WSe₂(0001)

A Photoemission Study of Solute−Solvent Interaction: Coadsorption of Na and H₂O on WSe₂(0001)

A Photoemission Study of Solute−Solvent Interaction: Coadsorption of Na and H₂O on WSe₂(0001)

UHV Model experiments of the semiconductor/electrolyte interface: Adsorption of I₂on n‐ and p‐doped WSe₂(0001)