Ge on Bi2Sr2-xCa1+xCu2O8+y: Reduced reactivity through cluster assembly.

Photoemission studies of low-temperature deposition of ∼30-Å-diam Ge clusters on single-crystal Bi2 Sr2-x Ca1+x Cu2 O8+y (100) show that an interface is produced with no evidence of substrate disruption. Analysis of the superconductor core level emission as a function of coverage indicates uniform overlayer growth and complete surface coverage. These cluster-assembled interfaces were stable when warmed to 300 K, with only a slight reduction of Cu 2p3/2 satellite emission characteristic of the superconductor. In contrast, conventional atom-by-atom Ge deposition produces a Ge oxide layer and surface disruption. [ABSTRACT FROM AUTHOR]