Interdiffusion in Au(120 nm)/Ni(70 nm) thin films at the low-temperature annealing in the different atmospheres

AbstractThe development of the interdiffusion processes and the surface morphology changes in thin films of Au(120 nm)/Ni(70 nm) during annealing at 200 °C for 20 min in vacuum with different residual atmosphere pressures of 10−3 and 10−6 Pa and in an environment of hydrogen at a pressure of 5 × 102 Pa have been studied. Secondary ion mass spectrometry, Auger electron spectroscopy, X-ray diffraction, optical microscopy, atomic force microscopy and scanning electron microscopy were used. Surface microdefects that form in the films are related to the local oxidation of nickel and to the stress that arises due to interdiffusion. Defect formation and reactions at the surface are found to be controlling factors in the transport of nickel to the surface and in the observed morphology

Nanoscale diffusion in Pt/56Fe/57Fe thin-film system

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Formation of CuxAu1−x phases by cold homogenization of Au/Cu nanocrystalline thin films

It is shown, by using depth profiling with a secondary neutral mass spectrometer and structure investigations by XRD and TEM, that at low temperatures, at which the bulk diffusion is frozen, a complete homogenization can take place in the Cu/Au thin film system, which leads to formation of intermetallic phases. Different compounds can be formed depending on the initial thickness ratio. The process starts with grain boundary interdiffusion, which is followed by a formation of reaction layers at the grain boundaries that leads to the motion of the newly formed interfaces perpendicular to the grain boundary plane. Finally, the homogenization finishes when all the pure components have been consumed. The process is asymmetric: It is faster in the Au layer. In Au(25nm)/Cu(50nm) samples the final state is the ordered AuCu3 phase. Decrease of the film thicknesses, as expected, results in the acceleration of the process. It is also illustrated that changing the thickness ratio either a mixture of Cu-rich AuCu and AuCu3 phases (in Au(25nm)/Cu(25nm) sample), or a mixture of disordered Cu- as well as Au-rich solid solutions (in Au(25nm)/Cu(12nm) sample) can be produced. By using a simple model the interface velocity in both the Cu and Au layers were estimated from the linear increase of the average composition and its value is about two orders of magnitude larger in Au (ca. 10−11 m/s) than in Cu (ca. 10−13 m/s)