ETHYLENE REACTIVITY WITH SILICON SURFACE

2004 ◽  
Vol 11 (01) ◽  
pp. 21-25 ◽  
Author(s):  
M.-A. ZAÏBI ◽  
J.-P. LACHARME
Keyword(s):  
Silicon Surface ◽  
Auger Electron ◽  
Low Energy ◽  
Second Step ◽  
Sticking Coefficient ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron ◽  
Electron Spectrometry ◽  
Property Changes ◽  
Initial Sticking

The clean Si (111)(7×7) surface has been exposed to ethylene ( C 2 H 4) doses, up to 7000 L (1 L =10-6 Torr ×1 s ) at most, under ultrahigh vacuum. The structural and electronic property changes of the surface have been studied by low energy electron diffraction (LEED), Auger electron spectrometry (AES) and photoemission yield spectroscopy (PYS). The interaction presents two types of kinetic adsorption, where the first is produced below 3000 L of C 2 H 4. In the first step, the ethylene molecule is adsorbed molecularly and the initial sticking coefficient S 0 is very low (S0≈2×10-3). At the saturation (≈ 5000–6000 L), the valence band is fitted by a power law (E — 4.42)2.5 eV .1,2 The surface is then a stronger scattering for photoemitted electrons. We attribute this result, produced at the second step of adsorption, to the C 2 H 4-π orbital and hydrogen liberated by this molecule, which break the Si – Si surface bonds.

Mechanism of Cu transport along clean Si surfaces

Open Physics ◽  
2003 ◽  
Vol 1 (3) ◽  
Author(s):  
A. Dolbak ◽  
R. Zhachuk ◽  
B. Olshanetsky
Keyword(s):  
Diffusion Process ◽  
Diffusion Coefficients ◽  
Electron Spectroscopy ◽  
Silicon Surface ◽  
Auger Electron ◽  
Effective Diffusion ◽  
Low Energy ◽  
Low Energy Electron Diffraction ◽  
Effective Diffusion Coefficients ◽  
Low Energy Electron

AbstractCu diffusion along clean Si(111), (110) and (100) surfaces are investigated by Auger electron spectroscopy and low energy electron diffraction. The effective diffusion coefficients of copper are measured in the temperature range from 500 to 650°C. It is shown that the Cu transport along silicon surface occurs by the diffusion of Cu atoms through Si bulk and the segregation of Cu atoms to the surface during the diffusion process. It is found that the segregation coefficients of Cu to silicon surface during the diffusion process depend on surface orientation.

TEMPERATURE-ACTIVATED REACTIONS OF H2O AND NH3 WITH H-PASSIVATED Si(111) SURFACES

2001 ◽  
Vol 08 (01n02) ◽  
pp. 25-31 ◽  
Author(s):  
M. A. ZAÏBI ◽  
C. A. SÉBENNE ◽  
J. P. LACHARME
Keyword(s):  
Auger Electron ◽  
Low Energy ◽  
Temperature Threshold ◽  
Low Energy Electron Diffraction ◽  
Interaction Processes ◽  
Surface Disorder ◽  
Small Density ◽  
Low Energy Electron ◽  
Low Pressures ◽  
Dipole Density

Chemically hydrogenated surfaces Si(111)(1×1)–H were exposed sequentially, at temperatures of up to 600°C, and to low pressures of H 2 O or NH 3. The interaction processes have been studied by low energy electron diffraction and by photoemission yield and Auger electron spectrometries. The temperature threshold for H 2 O reaction is 350°C, at which, in a first stage, OH dipoles replace adsorbed H. OH dipole density is limited below 1/3 monolayer by the Si–O–Si formation, which brings disorder and restores H passivation. For NH 3, the reaction threshold is 370°C, at which only a small density of NH 2 dipoles is stabilized at saturation. Beyond 370°C, the saturated NH 3/Si(111)–H reaction is characterised by an increasing substitution of NH 2 dipoles to H atoms. At higher temperatures, the loss of hydrogen leads to surface disorder, which induces a loss of the N-related dipole moment normal to the surface.

Heteroepitaxial System of h-BN/Monolayer Graphene on Ni(111)

2003 ◽  
Vol 10 (04) ◽  
pp. 697-703 ◽  
Author(s):  
T. Tanaka ◽  
A. Itoh ◽  
K. Yamashita ◽  
E. Rokuta ◽  
C. Oshima
Keyword(s):  
Vapor Deposition ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Elevated Temperatures ◽  
Chemical Vapor ◽  
Low Energy ◽  
Monolayer Graphene ◽  
Low Energy Electron Diffraction ◽  
Ni Substrate ◽  
Low Energy Electron

A heteroepitaxial system of h-BN/monolayer graphene on Ni(111) has been investigated by means of vibrational spectroscopy, accompanied by low energy electron diffraction (LEED) and Auger electron spectroscopy (AES). The system was prepared in an epitaxial manner on a Ni(111) surface by chemical vapor deposition (CVD). We found that phonon peaks in observed spectra showed typical features of Fuchs–Kliewer (FK) phonons. The vibrational spectra of h-BN films ranging in thickness from 0 to 8.7 monolayers have been compared with theoretical spectra based on a dielectric theory. Detailed analysis has revealed new types of phonons, of which the vibrational amplitudes are localized at edges of h-BN nanocrystals. In addition, we have observed subsidence phenomena of the graphene and h-BN layers into Ni substrate at elevated temperatures.

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