Improvement of YBa₂Cu₃O_x Single-Crystal Surface by Chemical Etching

Abstract

The single-crystal YBa 2 Cu 3 O x (YBCO) surface presents precipitates that aggregate to form a very thin damaged layer on the surface after mechanical polishing and thermal annealing. The damaged layer was removed by dipping it into a chemical etchant, HCl/methanol. After applying the etching process, YBCO(001) surfaces exhibited a well-defined step-and-terrace feature with unit-cell step height. No precipitates were observed from the etched substrates after annealing. Homoepitaxial films on etched substrates grew with unit-cell-high steps and step-edge facets, while those on as-polished substrates exhibited a grain structure with rough edges.