CHARACTERISTICS AND GROWTH-PROCESSES OF A SURFACE OXIDIZED LAYER FORMED ON AL-Y ALLOY-FILMS

The formation process as well as the characteristics of a surface oxid ized layer formed on Al-Y alloy films are examined. Al in the alloy fo rms a thin Al2O3 layer due to more oxidation Pt the alloy surface. In an alloy of Al-rich composition, if the Al2O3 surface layer (which is comparable to that formed on pure Al) is formed, the layer maintains i ts ability to be a self-passivating oxide layer. In those alloys that form an unduly thin Al2O3 surface layer, introduction of oxygen from t he ambient environment cannot be curtailed. As a result, oxidation pro ceeds and the formation of Y2O3 and reduced Al is observed within the oxide layer. In the oxidized layer, the oxidation state of the lesser amount of oxide is affected by that of the greater amount oxide; this reflects a shift in binding energy of the XPS spectra for the minor el ement. It is shown that the formation process of the alloy is dominate d by the differences of ionization potential, an element affinity, for mation heat, a diffusing species and the transport behavior of cations and/or anions.