Preparation of intrinsic Josephson junctions using Bi-2212 thin films

We fabricated intrinsic Josephson junctions 10 mu mx10 mu m in area using Bi2Sr2CaCu2Ox (Bi-2212) thin films with large grains employing a two-step annealing procedure. The first annealing step at a high temperature in O-2 is for the growth of crystal grains and the second step at a lower temperature in N-2 is for the control of the oxygen content in the film. By this method, Bi-2212 thin films with the c-axis critical current density J(c) of 10(1)-10(4)A/cm2 were obtained. A mesa structure was formed on the surface of the annealed film and we measured its electrical properties along the c-axis. The current voltage characteristics with clear hystereses and multiple branches were observed for the samples with J(c) of similar to 10(3)A/cm(2) or less. The gap structure was observed in the current-voltage characteristics for low mesas. J(c) and the voltage jump decreased more rapidly with increasing tem perature than those predicted by the BCS theory. We could obtain intrinsic Josephson junctions in Bi-2212 thin films with similar properties as in single crystal samples.