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An electron cyclotron resonance (ECR) ion beam has been utilized for a developing surface cleaning process of high‐Tc superconducting thin films. By means of silver‐contact resistivity measurements, and ex situ surface analysis using x‐ray photoelectron spectroscopy (XPS) and reflection high‐energy electron diffraction (RHEED), the effects of ECR treatment on an air‐exposed surface of a‐axis EuBa2Cu3O7−y (EBCO) films are examined. Ag/EBCO contacts are made with exposure of the EBCO surface to an ECR oxygen ion beam with ion current densities of 100 μA/cm2 at room temperature for about 30 min and the in situ deposition of silver. The contacts, which are not annealed in oxygen, exhibit low contact resistivity in the 10−8–10−7 Ω cm2 range. These values are about five orders of magnitude lower than those of samples fabricated without ECR treatment. Based on XPS and RHEED data, change in the EBCO surface caused by ECR treatment is surmised.

Photoemission studies of low‐temperature deposition of ∼30‐A‐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.