Simultaneous observation of oxygen uptake curves and electronic states during room-temperature oxidation on Si(0 0 1) surfaces by real-time ultraviolet photoelectron spectroscopy

Ogawa, Shuichi; Takakuwa, Yuji

doi:10.1016/j.susc.2007.04.044

Cited by 20 publications

(13 citation statements)

References 19 publications

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“…The different work functions of the samples were determined by fitting the SECOs according to

I_{SECO} (E) ~ H (E - E_{0}) \times G (E) {normale}^{- aE}

where H ( E − E 0 ) × G ( E ) was the convolution of a Heaviside step function with a Gaussian function, which accounted for the steep rise in intensity for kinetic energies higher than the work function, and e −aE accounted for the background. A similar expression was suggested by Ogawa et al and had proven to work well for determining the work function from SECO spectra. For more complex systems, like the ones investigated in this study, the background is more complicated.…”

Section: Methodsmentioning

confidence: 57%

Reliable Work Function Determination of Multicomponent Surfaces and Interfaces: The Role of Electrostatic Potentials in Ultraviolet Photoelectron Spectroscopy

Schultz

Lenz

Kotadiya

et al. 2017

Adv Materials Inter

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Ultraviolet photoelectron spectroscopy (UPS) is a key technique to determine the work function (Φ) of surfaces by measuring the secondary‐electron cut‐off (SECO). However, the interpretation of SECO spectra as obtained by UPS is not straightforward for multicomponent surfaces, and it is not comprehensively understood to what extent the length scale of inhomogeneity impacts the SECO. Here, this study unravels the physics governing the energy distribution of the SECO by experimentally and theoretically determining the electrostatic landscape above surfaces with defined patterns of Φ. For such samples, the measured SECO spectra exhibit actually two cut‐offs, one representing the high Φ surface component and the other one corresponding to an area‐averaged Φ value. By combining Kelvin probe force microscopy and electrostatic modeling, it is quantitatively demonstrated that the electrostatic potential of the high Φ areas leads to an additional energy barrier for the electrons emitted from the low Φ areas. Theoretical predictions of the induced energy barrier dependence on the Φ‐pattern length scale and sample bias are further experimentally verified. These findings establish a solid base for reliable SECO interpretation of heterogeneous surfaces and improved reliability of interfacial energy‐level diagrams from UPS experiments.

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“…The different work functions of the samples were determined by fitting the SECOs according to

I_{SECO} (E) ~ H (E - E_{0}) \times G (E) {normale}^{- aE}

Section: Methodsmentioning

confidence: 57%

Reliable Work Function Determination of Multicomponent Surfaces and Interfaces: The Role of Electrostatic Potentials in Ultraviolet Photoelectron Spectroscopy

Schultz

Lenz

Kotadiya

et al. 2017

Adv Materials Inter

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show abstract

“…The third possibility is band bending. 27,30,31) In this phenomenon, carriers are excited to the surface state, defect state, and impurity state of nitrogen in diamond by heating, and then the band near the surface is bent by charge accumulation. If the shift in the C 1s spectra is caused by band bending, the amount of the valence band maximum (VBM) shift should be the same as that of the C 1s spectral shift.…”

Section: Temperature Dependence Of C 1s Photoelectron Andmentioning

confidence: 99%

Vacuum Annealing Formation of Graphene on Diamond C(111) Surfaces Studied by Real-Time Photoelectron Spectroscopy

Ogawa

Yamada

Ishizduka

et al. 2012

Jpn. J. Appl. Phys.

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To clarify the graphene formation process on a diamond C(111) surface, changes in the chemical bonding state caused by annealing in vacuum were investigated by photoelectron spectroscopy using synchrotron radiation. It was difficult to study the formation of sp2-bonded carbon atoms on a diamond C(111) surface using photoelectron spectroscopy because the peak of the sp2 component overlaps the peak of the surface sp3 component as a result of the 2×1 reconstruction. Therefore, we focused on the shift in the C 1s photoelectron spectra and energy loss spectra caused by band bending depending on the temperature. As a result, we found that graphitization on the diamond C(111) surface began at approximately 1120 K, which was lower than that for a SiC substrate. The obtained photoelectron spectra indicated that a buffer layer composed of sp2-bonded carbon atoms existed at the interface between graphene and the diamond C(111) surface.

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“…2(a), black open squares), I PE rapidly increases with increasing V B up to ∼10 V and then remains almost at ∼0.2 µA independent of V B . The work function of Si is ∼5 eV [27], so excited photoelectrons can escape from the surface for 172-nm (7.2 eV) UV light irradiation, but their kinetic energies are < ∼2 eV. Such small kinetic energies of emitted photoelectrons account for the rapid increase followed by a plateau observed in the figure.…”

Section: Resultsmentioning

confidence: 93%

Catalyst-Free Growth of Networked Nanographite on Si and SiO2 Substrates by Photoemission-Assisted Plasma-Enhanced Chemical Vapor Deposition

Takami

Ogawa

Sumi

et al. 2009

e-J. Surf. Sci. Nanotechnol.

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We have developed a photoemission-assisted plasma-enhanced chemical vapor deposition (CVD) process, where DC discharge plasma is assisted by photoelectrons emitted from the substrate under ultraviolet (UV) light irradiation. Under Ar gas atmosphere and in vacuum, plasma current was measured as a function of sample bias voltage to clarify the mechanism, by which photoemission-assisted plasma is generated. Owing to the advantages of the photoemission-assisted plasma-enhanced CVD, where the plasma is generated close to the substrate and in a controllable volume, we have succeeded in growing shiny black films of networked nanographite, without any catalyst, on Si(001) and SiO2(350 nm)/Si(001) substrates at a deposition rate of ∼2 µm/min despite of low electric power consumption of plasma, ∼4 W. Cross-sectional transmission electron microscopy (TEM) and diffraction (TED) observations revealed that samples grown at ∼700 • C with Ar-diluted CH4 were composed of multilayer graphene particles (diameter of ∼10 nm) that were closely connected to each other and shared some graphene sheets between them, although their crystallographic configurations were randomly oriented. In bulk-sensitive C 1s photoelectron spectra using synchrotron radiation at 7933 eV, a chemically-shifted component of sp 2-bonded carbon atom was dominant and the π-π * transition loss peak was clearly observed for the samples grown on both substrates, indicating that the multilayer graphene particles substantially contain high-quality graphene sheets in agreement with evaluations by microscopic Raman spectroscopy. We named the layered carbon structure "carbon mille-feuille." [

show abstract

Simultaneous observation of oxygen uptake curves and electronic states during room-temperature oxidation on Si(0 0 1) surfaces by real-time ultraviolet photoelectron spectroscopy

Cited by 20 publications

References 19 publications

Reliable Work Function Determination of Multicomponent Surfaces and Interfaces: The Role of Electrostatic Potentials in Ultraviolet Photoelectron Spectroscopy

Reliable Work Function Determination of Multicomponent Surfaces and Interfaces: The Role of Electrostatic Potentials in Ultraviolet Photoelectron Spectroscopy

Vacuum Annealing Formation of Graphene on Diamond C(111) Surfaces Studied by Real-Time Photoelectron Spectroscopy

Catalyst-Free Growth of Networked Nanographite on Si and SiO2 Substrates by Photoemission-Assisted Plasma-Enhanced Chemical Vapor Deposition

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