The electronic structure and surface interactions of vapor-deposited Cu on single-crystal and polycrystalline ${\mathrm{Bi}}_2{\mathrm{Ca}}_{1+x}{\mathrm{Sr}}_{2-x}{\mathrm{Cu}}_2{\mathrm{O}}_{8+y}$ were studied using x-ray photoelectron spectroscopy. The results are compared to the $\frac{\mathrm{Cu}}{\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-x}}$ interface. Changes in the $\mathrm{Cu} 2p$ satellite emission indicate that the Cu adatoms do not disrupt ${\mathrm{Bi}}_2{\mathrm{Ca}}_{1+x}{\mathrm{Sr}}_{2-x}{\mathrm{Cu}}_2{\mathrm{O}}_{8+y}$ as extensively as $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-x}$. However, deposition of Cu induces changes in the Bi environment in the superconductor, and surface segregation of Bi metal was observed at high coverages. Core-level attenuation results suggest minimal out-diffusion of oxygen, in contrast with what is observed for $\frac{\mathrm{Cu}}{\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-x}}$.

• Received 11 July 1988

DOI:https://doi.org/10.1103/PhysRevB.38.11331