Method for changing surface termination of a perovskite oxide substrate surface

Abstract

A method for changing the surface termination of a perovskite substrate surface, an example of which is the conversion of B-site terminations of a single-crystal STO substrate to A-site terminations. The method generally comprises the steps of etching the substrate surface by applying a reactive plasma thereto in the presence of fluorine or another halogen, and then annealing the substrate at a temperature sufficient to regenerate a long range order of the surface, i.e., the surface termination contributes to a better long range order in a film epitaxially grown on the surface. More particularly, the resulting substrate surfaces predominantly contains A-site surface terminations, i.e., SrO for STO (100) substrates. As a result, disadvantages associated with B-site terminated perovskite substrate surfaces are avoided. A suitable etching treatment is a low power oxygen ashing in the presence of low halogen levels. A-site terminated surfaces produced by this invention allow for the epitaxial growth of heterostructures, such as cuprate films for use as high-T superconductor films, Josephson tunnel junctions, superlattices and OxFET, with improved quality.