Low‐power r.f. plasma oxidation of aluminium

Valence‐band and core‐level XPS have been used to characterize the structure and growth of aluminium oxidized in a low‐radiofrequency plasma. A change in the oxygen/aluminium ratio as a function of the metal substrate temperature during the plasma treatment correlated with changes in the valence band. Valence‐band width and shape indicated that the films were characteristic of γ‐alumina. The change in shape of the high‐binding‐energy component of the band suggested that structural changes occurred to the film as a function of temperature. Plasma film growth could be described in terms of the Cabrera–Mott theory of field‐assisted diffusion, with reaction velocities being higher than thermal oxidation rates reported in the literature. The reduction in the activation energy for plasma film growth was consistent with anion migration in a network‐forming oxide.