Surface segregation of aluminum atoms on Cu-9Â at.% Al(1Â 1Â 1) studied by Auger electron spectroscopy and low energy electron diffraction

Auger electron spectroscopy (AES) and low energy electron diffraction (LEED) were applied to investigate the segregation of aluminum atoms on a Cu-9 at.% Al(1 1 1) surface. We observed that the Al concentration in the top layer ranged between about 9 and 36 at.% after the sample we used was annealed at different temperatures. The phenomenon of Al atoms segregating on the surfaces was explained well by considering the diffusion length of Al atoms in bulk Cu. LEED measurements showed that (3×3)R30° structures grew as the concentration of Al atoms increased. The segregation phenomena on surfaces resulted in a stable two-dimensional Cu67Al33 alloy phase in the top layer.