Ion beam mixing, diffusion, and phase stability in Cu/Al2O3 interfaces

Abstract

Ion beam mixing, diffusion properties, and phase stability have been investigated in Cu/Al2O3 bilayer samples. Specimens were prepared by vapor deposition and irradiated with 150 keV Ar+ ions up to a fluence of 1.5 · 1017 Ar+/cm2. Sample temperature under irradiation was varied between 77 K and 673 K. The mixing behavior was studied by analyzing the concentration depth profiles, determined by Rutherford Backscattering Spectroscopy. It was found that mixing efficiencies of Cu, Al, and O scale with Ar+ fluence. Radiation enhanced diffusion (RED), observed above room temperature, is separated from ballistic mixing and high temperature diffusion. The migration enthalpy for interdiffusion in the RED region (between RT and 300 °C) was estimated to be approximately 0.3 eV. Sputtering yields depending on temperature gradient near to sample and phase stability versus ion dose and temperature are also discussed.