Kinetics of phase formation in Au—A1 thin films

Abstract

Phase formation was studied in Au-A1 thin films by means of MeV He⁺ back-scattering and glancing angle X-ray diffraction techniques. In the initial stages of compound formetion where both unreacted Au and unreacted A1 layers are present, the phases Au₅Al₂ and Au₂Al are found. The end phases of the low-temperature treatments (150–300°C) are AuAl₂ or Au₄Al in the presence of only unreacted Al or Au, respectively.

The kinetics of the growth of the Al-rich compounds follow a (time)^1/2 dependence. The activation energies for the growth of Au₂Al and AuAl₂ are 1.0 and 1.2 eV, respectively.