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

Abstract
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.