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electrolyte interface
A436 Surface Science 134 (1983) 865-885 North-Holland Publishing Company
865
SURFACE STATES Si/ELECTROLYTE
INDUCED BY METAL INTERFACE
J.-N. CHAZALVIEL
and M. STEFENEL
ATOMS
AT THE
*
Laboratoire P M C **, Ecole Polytechnique, F-91128 Palaiseau C~dex, France
and T.B. TRUONG LA 75, Laboratoire de Physico-Chimie des Rayonnements, Bgttiment 350, Unwerslt~ Paris-Sud, F- 91405 Orsay, France
Received 18 May 1983; accepted for publication 15 August 1983 Metal atoms have been chemically deposited on n-Si and p-Si and the obtained deposits have been characterized with Auger electron spectroscopy. The obtained samples have been used as electrodes in acetonitrile electrolyte. The electrochemical studies have been performed using classical current-voltage, impedance and Schottky-Mott measurements, and also subgap photocurrent spectroscopy of the surface states. It appears that the deposited metal atoms do induce surface states on the silicon surface. These surface states have a weak effect on the flatband potential (i.e. no strong pinning of the Fermi level is observed even for monolayer coverage) but the subgap photoyield is increased by several orders of magnitude. The shape of the quantum yield versus photon energy curve points to surface states widely distributed through the bandgap. These experiments finally confirm the ability of the subgap photocurrent technique to distinguish between the two kinds of optical processes that may occur between the surface states and the semiconductor bands.
886 STUDY
Surface Science 13,1 (1983) 886-892 North-Holland Publishing Company OF LEED
J.-M. BARIBEAU
FINE S T R U C T U R E S O N T H E O - W ( 0 0 1 ) * and J.-D. CARETTE
SYSTEM
**
Dbpartement de Physique et Centre de Recherches sur les Atomes et les Molbcules, Universitb Laval, Quebec, Canada GI K 7P4 Received 23 June 1983; accepted for publication 26 August 1983
In earlier work it was established that fine structure features observed in very low-energy-electron-diffraction were very sensitive to surface contamination. We report a study of the effect of oxygen adsorption on the intensity profile of the specular beam on W(001) in a variety of surface conditions. It is found that specific fine structure line shapes can be associated with the reconstructed annealed surface at half and full coverage. Under the assumption that the intensity of the fine structures is closely linked to the surface smoothness, our observations are compared with results obtained with other techniques and several adsorption models are discussed.
865
SURFACE STATES Si/ELECTROLYTE
INDUCED BY METAL INTERFACE
J.-N. CHAZALVIEL
and M. STEFENEL
ATOMS
AT THE
*
Laboratoire P M C **, Ecole Polytechnique, F-91128 Palaiseau C~dex, France
and T.B. TRUONG LA 75, Laboratoire de Physico-Chimie des Rayonnements, Bgttiment 350, Unwerslt~ Paris-Sud, F- 91405 Orsay, France
Received 18 May 1983; accepted for publication 15 August 1983 Metal atoms have been chemically deposited on n-Si and p-Si and the obtained deposits have been characterized with Auger electron spectroscopy. The obtained samples have been used as electrodes in acetonitrile electrolyte. The electrochemical studies have been performed using classical current-voltage, impedance and Schottky-Mott measurements, and also subgap photocurrent spectroscopy of the surface states. It appears that the deposited metal atoms do induce surface states on the silicon surface. These surface states have a weak effect on the flatband potential (i.e. no strong pinning of the Fermi level is observed even for monolayer coverage) but the subgap photoyield is increased by several orders of magnitude. The shape of the quantum yield versus photon energy curve points to surface states widely distributed through the bandgap. These experiments finally confirm the ability of the subgap photocurrent technique to distinguish between the two kinds of optical processes that may occur between the surface states and the semiconductor bands.
886 STUDY
Surface Science 13,1 (1983) 886-892 North-Holland Publishing Company OF LEED
J.-M. BARIBEAU
FINE S T R U C T U R E S O N T H E O - W ( 0 0 1 ) * and J.-D. CARETTE
SYSTEM
**
Dbpartement de Physique et Centre de Recherches sur les Atomes et les Molbcules, Universitb Laval, Quebec, Canada GI K 7P4 Received 23 June 1983; accepted for publication 26 August 1983
In earlier work it was established that fine structure features observed in very low-energy-electron-diffraction were very sensitive to surface contamination. We report a study of the effect of oxygen adsorption on the intensity profile of the specular beam on W(001) in a variety of surface conditions. It is found that specific fine structure line shapes can be associated with the reconstructed annealed surface at half and full coverage. Under the assumption that the intensity of the fine structures is closely linked to the surface smoothness, our observations are compared with results obtained with other techniques and several adsorption models are discussed.