Interface-dominated Growth of a Metastable Novel Alloy Phase

A new D023 metastable phase of Cu3Au is found to grow at the interfaces of Au/Cu multilayers deposited by magnetron sputtering. The extent of formation of this novel alloy phase depends upon an optimal range of interfacial width primarily governed by the deposition wattage of the dc-magnetron used. Such interfacially confined growth is utilized to grow a ∼ 300 nm thick Au/Cu multilayer with thickness of each layer nearly equal to the optimal interfacial width which was obtained from secondary ion mass spectrometry (SIMS) data. This growth technique is observed to enhance the formation of the novel alloy phase to a considerable extent. SIMS depth profile also indicates that the mass fragment corresponding to Cu3Au occupies the whole film while x-ray diffraction (XRD) shows almost all the strong peaks belonging to the D023 structure. High resolution cross-sectional transmission electron microscopy (HR-