M. Aucouturier

Physico-chemical characterisation of native air-formed oxide films on Al-Mg alloys at low temperature. Influence of water

Natural oxide films on two cold-rolled Al-Mg alloys were studied using several techniques (XPS, SIMS, ToF-SIMS, GDOS, SEM, TEM, Wetting measurements). The aim was to characterise and compare the oxide layers formed on the two materials in order to better understand the influence of the thermomechanical history. The experimental tools used allowed the determination of the influence of the annealing process on the nature and structure of the oxides. The hydration and Brönsted behaviour were also investigated. The thickness of the layer, the amount of magnesium oxide and its dissolving resistance in water are strongly modified by the annealing. The oxide film formed on the annealed material is twice as thick as the one on the non-reheated material. The layer on the annealed material contains more magnesium oxide and contains the crystalline forms:β-Al2O3 and bayerite (Al(OH)3). On the contrary, the oxide film formed on the as-rolled material seems to be amorphous. The magnesium oxide is less soluble in water in the annealed film than in the non-reheated one. Furthermore, aluminium and magnesium oxides were found to be hydroxylated on both alloys, and the layer surfaces to behave like a Brönsted meaning base.

On the modeling of hydrogen diffusion processes and complex formation in p-type crystalline silicon

Deuterium diffusion profiles in p-type silicon doped with boron (1017–1019 cm-3) and aluminum (1018 cm-3) are simulated with an improved version of a previously reported model. The new approach, based on the observation of experimental profiles, excludes H2 molecule formation and leads to a reduced fit parameters model. The different diffusion coefficients and activation energies of H0 and H+ species are determined and discussed in the light of available data. The dissociation energies of BH and AlH complexes are also calculated and found to be in good agreement with the corresponding reported values in the literature.

Photocathodic hydrogenation of p‐type silicon

An electrolytic technique is shown to introduce hydrogen into p‐type silicon at room temperature. The penetration depths investigated by secondary ion mass spectroscopy are found to be strongly dependent on the doping level. These differences are explained in terms of a donor hydrogen‐related level close to the midgap.

Influence of thermal treatments on the distribution of contaminating copper near the surface of silicon : a comparative SIMS and XPS study

Abstract Quantitative analysis of the concentration profile of copper introduced into silicon by mechanochemical polishing is performed by XPS and SIMS techniques. The evolution of the copper distribution after thermal treatments (450, 750, 900°C) is followed by the same techniques. The results show that an important segregation towards the surface and the near-surface regions occurs during the thermal annealings. Electron-probe X-ray images and SIMS ionic images, as well as the quantitative analysis show that copper is in a precipitated state, sometimes associated with oxygen and carbon.

Correlation between Lewis donor/acceptor properties determined by XPS and Brnsted acid/base properties determined by rest-potential measurements, for aluminium and silicon oxides

In order to qualify the reactivity of various aluminium and silicon oxide substrates for elastomer adhesion applications, X-ray photoelectron spectroscopy (XPS) and rest-electrochemical potential measurements have been performed on those surfaces. The interpretation of XPS binding energy shift measurements in terms of Fermi level variation from one surface to another, as proposed by Mullins and Averbach in 1988, is discussed in view of results on an aluminosilicate compound surface. The correlation with electrochemical restpotential measurements on an anodized aluminium surface and a silane coupling agent is described and discussed. The possibility of surface reactivity assessment through correlated XPS and electrochemical measurements for metal oxides is demonstrated.

Electrolytic hydrogenation of p-type silicon bulk and surface modifications

An electrolytic method is used to introduce hydrogen into p-type silicon, at room temperature. The results of SIMS analysis indicate that hydrogen diffuses more rapidly in highly doped samples than in low doped samples, in contrast with the results of plasma annealing. The electrochemical technique creates a large number of surface defects, probably related to the existence of a thin hydrogenated layer beneath the surface.

Hydrogen at semiconductor grain boundaries and interfaces

This paper is a review of the known effects of hydrogen in crystalline semiconductor grain-boundaries and interfaces and of the recent progress in the fundamental study of the mechanisms of hydrogen-interfaces interactions. The interfaces considered are: grain boundaries of polycrystalline semiconductors, semiconductor/semiconductor or semiconductor/metal interfaces, silicon/silicon oxide interfaces (including precipitated silicon oxide interfaces), and semiconductor/electrolyte interfaces. The influence of structural and electronic defects on the hydrogen passivation processes is discussed. Emphasis is laid upon the role of segregated impurities on the electrical activity of interfaces and its subsequent passivation by hydrogen. Some ideas are given for development of experimental and theoretical research to improve the understanding of the mechanisms of hydrogen action.

Hydrogen Diffusion in N-Type Silicon.Comparison With P-Type Silicon

Deuterium diffusion profiles in medium phosphorus doped silicon (10 16 and 10 17 cm −3 ) at two different deuteration temperatures (120 and 150°C) are simulated with an improved version of a previously reported model. The new approach which excludes the H 2 molecule formation, as applied recently to ptype silicon, allows the determination of kinetic and thermodynamic parameters such as diffusion coefficients, activation and dissociation energies. These parameters 6re compared with those found for p-type silicon and discussed in the light ofavailable data for n-type material.

Behavior of Hydrogen Introduced Under Plasma Discharge or Cathodic Polarization into Silicon

This paper concerns recent results on hydrogen introduction, diffusion and behavior in mono and bicrystalline silicon. Plasma annealing, cathodic charging, SIMS profiling, capacity-voltage measurement and LBIC cartography are used. The results are discussed in terms of hydrogen-impurities and hydrogen-defects interactions.