Crystallization of Au_xSi_1−x amorphous alloys

Abstract

Amorphous Au _x Si_1−x alloys have been prepared by vapour deposition at 77 K over a wide range of composition (0 ⩽ x ⩽ 0·80). Crystallization has been studied by electrical resistivity measurements, electron microscopy and diffraction. A metastable crystalline phase μ is formed before reaching the equilibrium dissociation into crystalline gold and silicon. This metastable phase has a composition near Au₃Si and may be obtained alone or in a mixture with silicon depending on the amorphous alloy composition. Short-range order in the amorphous material is discussed with respect to the structure of the μ phase. It is suggested that amorphous alloys appear to exist as a single phase only at the Si-rich end of the composition range and near the eutectic composition.