Study of the sputter rate of thin aluminium layers deposited on polymer (PET) substrates

Aluminium thin layers thermally evaporated on polyethylene terephthalate (PET) films were sputter etched by 2 keV Xe ion bombardment. Significant sputter rate differences are observed for layers deposited under different metallization conditions and on different PET substrates. Differences in grain sizes are observed by transmission electron microscopy for the Al layers whereas no difference either in crystallographic orientations or in phase composition is observed on the electron diffraction patterns. The depth-composition profiles of impurities are obtained by SIMS: they show that higher mean sputter rates are achieved for Al layers and Al/PET interfaces containing less oxygen. These differences are shown to be related not only to the depth composition profiles of the impurities in the Al layers and to the Al/PET interface chemistry but also to the microstructure of the Al layers. A decrease of sputter yield is observed for samples exhibiting Al grain sizes greater than the Al layer thickness.Anglai

A general mechanism for gel layer formation on borosilicate glass under aqueous corrosion

International audienceMineral and glass dissolution is a scientific topic deeply investigated but incompletely understood and of a great interest for the geochemical and materials science communities. If the interfacial dissolution/reprecipitation mechanism seems to be applicable to most of silicate minerals, the debate remains open concerning glass. Here we studied two model glasses, a ternary borosilicate (CJ1) and the same glass doped with 4.1 mol % of Al2O3 (CJ2). The two glasses were altered at 90°C, pH 9, and in conditions far and close to saturation with respect to amorphous silica, to determine the initial and residual rates. Moreover, a specific experiment was conducted for a short duration with a solution highly enriched with 18O and 29Si isotopes to understand how passivating gels form. SEM, TEM and ToF-SIMS characterization, along with Monte Carlo simulations were used to understand the rate limiting reactions at play and infer the role of Al. We show that Al yields a slower matrix dissolution in dilute conditions. However, it slows down the formation and the maturation of the passivating gel and favors alteration by partial hydrolysis of Si and Al entities followed by in-situ reorganization/relaxation into a porous network. Unexpectedly, CJ1 experienced both interfacial dissolution/reprecipitation and partial hydrolysis followed by in situ reorganization of the silicate network during the course of a single experiment. This study offers a unified concept that can pave the way for the future development of a predictive kinetic model based on a detailed description of bond breaking and bond forming as a function of glass composition and alteration conditions

The influence of sprayed (Cd,Zn)S on dipped Cu/sub x/S composition

It is shown that the properties of sprayed (Cd,Zn)S layers obtained by means of a pneumatic nozzle depend dramatically on the type of flow gas used (air or nitrogen). The role of chemisorbed oxygen is demonstrated. Independently of the various heat treatments applied, the resulting Cu/sub x/S obtained has always a coefficient x closer to 2 when the flow gas is nitrogen. A subsequent annealing of the (Cd,Zn)S layers is found to increase the Cu/sub x/S growth speed. It is also shown that the quality of (Cd,Zn)S layers determines to a great extent that of the cuprous sulfide in (Cd,Zn)S-Cu/sub x/S heterojunctions. The data are interpreted in terms of the modification of the layers structure, composition and charge carrier concentration.Anglai

Modification of polymer (PET) surface reactivity by low energy ion bombardment

The surface of polyethylene terephthalate (PET) was studied by low energy He/sup +/ ion scattering (ISS). Modifications of the surface composition induced by the He/sup +/ and Ar/sup +/ bombardments are observed. The ion bombardment causes surface damages with bond breaking and it results a highly activated surface for the chemisorption of nitrogen from the residual gas phase. Similar effects were observed on highly oriented pyrolytic graphite when analyzed in the same beam conditions.Anglai