Investigations of the surface morphology of La2CuO4 MBE-grown thin films before and after electrochemical oxidation

Scanning probe microscopes have been used to investigate the surface morpho logy of MBE-grown, c-axis oriented, La2CuO4 thin films upon electrochemical oxidation. These investigations show evidence of the formation of an insul ating layer on top of the thin film, which grows with increasing electroche mical oxidation. This layer partially dissolves in 1 M KOH after a long exp osure time and leads to a roughening of the surface. Experiments with submi cron patterned samples prepared by a masking technique indicate that the fo rmation of oxygen-intercalated patterns by localized electrochemical oxidat ion is, in principle, possible. If the appropriate oxidation time is applie d, then the resulting patterns are remarkably stable in the film (over 7 mo nths) but the surface layer of the patterned domains is unstable. (C) 2000 Elsevier Science B.V. All rights reserved.