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

► The atmosphere alters diffusion rates of Ni in an Au layer at 200 °C. ► Local defects with higher Ni concentration occur after annealing in vacuum 10−3 Pa. ► Hydrogen atmospheres or vacuum of 10−6 Pa provide smooth surfaces after annealing. ► Defects arise from local oxidation and the stress caused by interdiffusion.