engleski

Relaxation behaviour of the Al-based amorphous thin films

Thin films of Al-(Nb, Mo, Ta, W) have been prepared by magnetron codeposition in the CMS 18 sputtering system onto various substrates held at room temperature and in a wide range of composition. Structural relaxation under isochronal heating conditions of the completely amorphous (nanocrystalline) thin films was examined by a continuous in situ electrical resistance measurements in vacuum. The structure of the as-deposited and heated films was examined by the XRD. Preliminary experimental results suggests that the relatively high relaxation effects, as observed in the electrical resistivity, in the Al-W and Al-Mo films have a maximum for the films with about 70-80 at% of Al. For the Al-W amorphous films relaxation effects also decreased with an increase of the heating rate. For the Al-Nb and Al-Ta amorphous films, the relaxation effects were not so strong, probably due remarkable low crystallization temperatures which are around or below 300OC. Inspection of the resistivity versus temperature data suggests that the relaxation kinetics in Al-W and Al-Mo thin films can be described by the phenomenological JMA kinetic law for isothermal transformation. The adaptation of the JMA model to the non-isothermal kinetics was used for calculation of kinetic parameter n. The calculated results indicated that the kinetic parameter n in AlW amorphus thin films increases from approximately 0.4 to 0.8 with increasing of the aluminum content. High relaxation effects we ascribe to the sp-d hybridization through which even the small changes in the interatomic distances can strongly affects the electrical properties of Al-transition metal alloys. This view is strongly supported by Hall effect results, available for the Al-W thin films.

Relaxation; Al-based alloys; amorphous thin films

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