Growth of untwinned Bi2Sr2Ca2Cu3Ox thin films by atomically layered epitaxy

Abstract
We report the growth of untwinned epitaxial thin films of Bi‐Sr‐Ca‐Cu‐O by atomically layered heteroepitaxy on SrTiO3 substrates. These films are c‐axis oriented as‐layered and do not exhibit 90° in‐plane defects, i.e., ab ‘‘twinning.’’ By misorienting the surface normal from {100} by approximately 4° towards 〈111〉, the cubic symmetry of the {100} surface is adequately broken to completely align the b axis of the superconducting film with respect to the substrate. Reflection high‐energy electron diffraction patterns observed during growth and post‐growth x‐ray diffraction analysis indicate that the incommensurate structural modulation occurs along the same direction as the step edges.