LEED AND AES ANALYSES OF CU-PD ALLOY SURFACE PREPARED BY EVAPORATION AND ANNEALING

The structure and composition of the Cu-Pd alloy surfaces prepared by depositing palladium onto {100}, {110} and {111} surfaces of copper, and by subsequent heating, have been investigated by LEED and AES. Streak, c(2 × 2) and (1 × 1) LEED patterns have been observed on the {100} surface with decreasing palladium content, and (1 × 1)I, (2 × 1) and (1 × 1) patterns have been observed on the {110} surface. On the {111} surface no characteristic LEED pattern was observed other than the (1 × 1) pattern. Surface periodicities of the c(2 × 2) structure on the {100} surface and of the (2 × 1) structure on the {110} surface agree with those expected if one passes a mathematical plane through the bulk ordered structure of Cu3Pd(α'). The dependence of the appearance of the surface structure on the thickness of the palladium deposited and on the substrate temperature during the deposition has been investigated. The c(2 × 2) structure on the {100} surface appears under various conditions of thickness and temperature. Surface segregation in the Cu-Pd alloy is shown to be small by analyzing the data of AES at 60 eV (Cu), 330 eV (Pd), 770 eV (Cu) and 840 eV (Cu). © 1979.