AbstractSuperconducting thin films of YBa2Cu307‐x were grown on MgO (100) and YSZ(IOO) substrates without post‐annealing by metal organic chemical vapor deposition using vertical, high‐speed (1100 rpm) rotating disk reactor. The source materials were Y(tmhd)3, Ba(tmhd)2, and Cu(tmhd)2, which were kept at 135 °C, 240 °C, and 120 °C respectively. The precursors were transported using nitrogen as the carrier gas and introduced separately into the cylindrical stainless steel reaction chamber, which was maintained at 60 torr. The oxygen partial pressure was 30 Torr. The substrates were heated resistively at 800°C. After growth, the films were cooled down at a rate of 5 °C/min under 1 atmospheric pressure of pure oxygen. The X‐ray diffraction pattern of the films showed primarily an orientation of c‐axis perpendicular to the substrates, with weak peaks of (hoo) corresponding to a‐axis orientation. Scanning Electron Microscopy of the films showed a well‐developed a‐axis and c‐axis plate‐like structure which appeared as rectangular micron‐sized features on the MgO surface. On the YSZ substrates a‐axis and c‐axis plate‐like projections were also observed, with the dense plate‐like c‐axis orientation dominant. Four probe resistance measurements showed Tc(R=0) at 91.8 K(△TC=2.2 K) and 85 K (△TC=7 K) on YSZ and MgO substrates respectively.
