(110) NdBa₂Cu₃O_7-δ and YBa₂Cu₃O_7-δ Films Grown on (110) NdBa₂Cu₃O_7-δ Single Crystal Substrates by 90° Off-Axis RF Magnetron Sputtering Methods

Abstract

Atomically flat surfaces of (110) oriented NdBa 2 Cu 3 O 7-δ and/or YBa 2 Cu 3 O 7-δ films grown on mechanically polished (110) NdBa 2 Cu 3 O 7-δ single crystal substrates are confirmed by reflection high energy electron diffraction (RHEED) and scanning electron microscopy (SEM) observations. All of these thin films are grain free “epitaxial” films as smooth as (110) YBa 2 Cu 3 O 7-δ homoepitaxial films [Usagawa et al. .: Jpn. J. Appl. Phys. 36 (1997) L100.]. Our experimental results strongly suggest that the origin of the ultrasmooth surface morphology of (110) YBa 2 Cu 3 O 7-δ (NdBa 2 Cu 3 O 7-δ ) films will be due to the inherent nature of (110) surfaces of 123 structures.