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We investigate the effects of oxygen on the thermal diffusion of germanium atoms, implanted inside a thermally grown SiO2 layer, during high temperature processes (1100 °C, 60 min). The impact of the presence of oxygen on Ge diffusion is studied as a function of its origin, as it can come either from the annealing atmosphere (extrinsic source) or from the SiO2 matrix itself (intrinsic source). 18O labeling of the oxygen either in the annealing atmosphere or in the silica substrate, together with an isotopically sensitive ion beam analysis, shows a clear oxygen-dependence in germanium diffusion. This is especially so when oxygen is present in the annealing atmosphere, where it is responsible for an enhancement of germanium out-diffusion and redistribution into several peaks during annealing, through the formation of GeO molecules. A new three-process model is proposed to explain the impact of a contaminated atmosphere on the Ge redistribution. This is notably shown that a third Ge peak arises at the sample surface when the annealing atmosphere is contaminated by oxygen. This peak formation is explained by the oxidation of Ge present at the vicinity of the surface by oxygen coming from the annealing atmosphere. This is also shown that O2 molecules can diffuse in depth, with a coefficient of diffusion D O 2 ∼ 10 − 9 c m 2 / s , until the densities of Ge and irradiation-induced defects increase, causing the progressive oxidation of Ge in depth and the restoration of the SiO2 stoichiometry. [ABSTRACT FROM AUTHOR]

Issues concerning the vital parameters for oxygen exchange at the Si-SiO2 interface are discussed.

The cross-sections of deuteron-induced nuclear reactions suitable for ion beam analysis, measured in different laboratories, are often significantly different. In the present work, differential cross-sections of 27Al(d,p) and 27Al(d,α) reactions were measured, and the cross sections benchmarked with thick target spectra obtained from pure aluminium for the first time in two independent laboratories. The 27Al(d,p) and (d,α) differential cross-sections were measured between 1.4 and 2 MeV at scattering angles of 165°, 150°, and 135° in the VDGT laboratory in Tehran (Iran), and the same measurements for detector angle of 150° were repeated from scratch, including target making, with independent equipment on the SAFIR platform at INSP in Paris (France). The results of these two measurements at 150° are in good agreement, and for the first time a fitted function is proposed to describe the Al-cross sections for which no suitable theoretical expression exists. The obtained differential cross-sections were validated through benchmarking, by fitting with SIMNRA deuteron-induced particle spectra obtained from a high purity bulk Al target at both labs for deuteron incident energies between 1.6 and 2 MeV. The thick target spectra are well-reproduced. The evaluated and benchmarked cross sections have been uploaded to the ion beam analysis nuclear data library database (www-nds.iaea.org/ibandl/). [ABSTRACT FROM AUTHOR]

Oxygen exchange reactions may occur between oxygen molecules or between oxygen from the gas phase and the oxygen in SiO2, both at the surface and at the Si-SiO2 interface during dry thermal oxidation of silicon. The oxygen exchange rate at the Si-SiO2 interface was at least 25% of the oxygen uptake rate, requiring the movement of oxygen both from the surface to the interface, and from the interface to the surface.

Nuclear reaction narrow resonance tests and sequential treatments in natural oxygen (16O2) and in heavy oxygen (18O2) for a Joule effect furnace indicated a below-surface oxygen atom exchange from the gas phase and from silica, including silica films thicker than 20 nm. Analysis of SiO2 film thermal growth also showed diffusion of near surface defects in the process of silicon thermal oxidation.

The epitaxial growth of β-Sic nanocrystals at the Si16O2/Si(100) interface under CO annealing has been studied using 13C18O and isotopically sensitive nuclear reaction analysis and secondary ion mass spectrometry analysis. The results show that the amount of SiC increases linearly with the CO pressure and the annealing time. We demonstrate that the CO diffuses as a molecule in the silica and that for each C atom reacting to form SiC, an oxygen atom is incorporated in the vicinity of the interface. The linear and the parabolic rate constants corresponding to an adapted Deal and Grove model are also determined. [ABSTRACT FROM AUTHOR]

We present some experimental results and propose a reaction-diffusion model to describe thermal growth of silicon oxynitride films on Si in NO and N[sub 2]O, as well as annealing in NO of thermally grown silicon oxide films on Si. We obtain growth kinetics and N and O depth distributions for the different growth routes by changing only initial and boundary conditions of a set of nonlinear differential equations. The results suggest that the puzzling differences in film growth rate and N incorporation originate from dynamical effects, rather than in differences in chemical reactions. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The epitaxial growth of [beta]-SiC nanocrystals at the Si[super 16][O.sub.2]/Si(100) interface under CO annealing is analyzed by using [super 13]C[super 18]O and isotopically sensitive nuclear reaction analysis and secondary ion mass spectrometry analysis. The amount of SiC has increased linearly with the CO pressure and the annealing time and the CO has diffused as a molecule in the silica.

The different phases formed in Zn1−xFexO thin films where x varies from 0 to 1, as well as their structural characteristics and physical properties, have been investigated. In particular, the interrelationships between the iron concentration, the oxygen composition and the microstructure of the films have been determined. The Zn1−xFexO films were grown on c-cut sapphire substrates by pulsed-laser deposition. For 0 ＜ x ＜ 0.35, epitaxial films with a wurtzite (ZnO like) structure were obtained, while for 0.65 ＜ x ＜ 1, spinel (Fe3O4 like) epitaxial films were observed. In the intermediate region (0.35 ＜ x ＜ 0.65) the phase separation of the Zn1−xFexO films leads to the formation of both wurtzite and spinel phases. Whatever is the x value, the films display well-defined in-plane epitaxial relationships between the wurtzite (or spinel) phase and the substrate. The optical, electrical and magnetic properties of the Zn1−xFexO films are discussed in relation with their structural characteristics. [ABSTRACT FROM AUTHOR]