Scanning tunneling microscopy study on YBa 2Cu 3O 7−x films with growth stop by observing reflection high-energy electron diffraction oscillations

Abstract

The growth of YBa 2Cu 3O 7−x thin films was stopped on a maximum or a minimum of an intensity oscillation in reflection high- energy electron diffraction (RHEED). The resulting film surfaces were observed by scanning tunneling microscopy. Films stopped on a maximum have smoother surfaces, closer to the completion of a monolayer of unit cells, than those on a minimum. The width of monolayer terraces was almost the same as that of the substrates determined from the misorientation. On the terraces, islands of one unit cell height were observed, so that the diffusion length of YBa 2Cu 3O 7−x must be shorter than the terrace size.