EVIDENCE FOR STEP FLOW GROWTH OF BI-SR-CA-CU-O THIN-FILMS ON VICINAL SUBSTRATES BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION

Two-dimensional nuclei and the resulting two-dimensional islands as well as the steps were observed at the surface of the Bi-Sr-Ca-Cu-O thin films grown on the vicinal substrates misoriented by 1-degrees, but only the steps were observed at the surface of the films grown on the vicinal substrates misoriented by 5-degrees. The step distance of the films grown on the vicinal substrates misoriented by 1-degrees was longer than those of the films grown on the vicinal substrates misoriented by 5-degrees. The competition between the propagation of the surface steps and the formation of two-dimensional nuclei can be explained qualitatively by the relation between the step distance and the mean time for surface diffusion of the adsorbing species. These results experimentally indicate that the growth of Bi-Sr-Ca-Cu-O thin films on vicinal substrates have proceeded in the step flow mode.