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

Abstract

Scanning probe microscopes have been used to investigate the surface morphology of MBE-grown, c-axis oriented, La2CuO4 thin films upon electrochemical oxidation. These investigations show evidence of the formation of an insulating layer on top of the thin film, which grows with increasing electrochemical oxidation. This layer partially dissolves in 1 M KOH after a long exposure time and leads to a roughening of the surface. Experiments with submicron patterned samples prepared by a masking technique indicate that the formation of oxygen-intercalated patterns by localized electrochemical oxidation is, in principle, possible. If the appropriate oxidation time is applied, then the resulting patterns are remarkably stable in the film (over 7 months) but the surface layer of the patterned domains is unstable.