Atomic and electronic structure of amorphous Al-Zr alloy films

• Amorphous Al73Zr27 alloy film, grown and then subjected to heat treatments at 400 and 700 degrees C, was studied using a combination of x-ray diffraction and soft x-ray spectroscopic techniques. The Al L-2,L-3 and Al K x-ray absorption spectroscopy (XAS) and Al L-2,L-3 x-ray emission spectroscopy (XES) used allowed probing the unoccupied and occupied Al 3s, d states and unoccupied Al 3p states in the sample studied. An irreversible transition from amorphous alloy to a mixture of polycrystalline alloy and amorphous alloy, and then to an amorphous oxide phase was observed. After the annealing at 400 degrees C the Al L-2,L-3 spectra obtained by XAS could be explained as sums of spectra from amorphous Al73Zr27 alloy and (poly) crystalline Al. This indicates that the sample consists of a mixture of Al-rich crystalline and Zr-enhanced amorphous alloys, as compared to the stoichiometry of the as-deposited Al73Zr27 sample, and that the electronic wavefunctions in the crystalline and amorphous regions can be considered to be confined within the respective regions. The relative amounts of Al atoms were found to be around 1: 3 in the crystalline and amorphous phases, respectively, as deduced from the analysis of changes in the electronic structure using Al L-2,L-3 XAS data. The interpretation was confirmed by the Al K XAS and Al L-2,L-3 XES. Upon further annealing at 700 degrees C the polycrystalline phase transformed into amorphous oxide, while the amorphous alloy phase underwent gradual oxidation. The important finding was that the greater part of the sample remained in the amorphous state throughout the temperature regimes described.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

X-RAY-ABSORPTION

NEAR-EDGE STRUCTURE

EMISSION

SPECTROSCOPY

ALUMINUM

METALS

OXIDES

MG

Physics

Fysik

NATURAL SCIENCES

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