Growth of EuBa₂Cu₃O_7-δ films under an ozone atmosphere

We have investigated the dependence of the crystallinity and the superconducting characteristics in the EuBa₂Cu₃O _7-δ (EuBCO) thin films on oxygen content. The EuBCO films were grown using a pulsed laser deposition (PLD) under an oxygen and an ozone atmosphere on (1 0 0) SrTiO₃ substrates. The c-axis length of as-grown EuBCO films under the oxygen atmosphere was longer than that of the bulk. The c-axis length of in situ annealed EuBCO films was shortened as compared with the as-grown EuBCO films. Additionally, the surface resistance (R_s) of the in situ 3 and 6 h annealed EuBCO films was lower than that of as-grown EuBCO films. However, the surface resistance of in situ annealed more than 24 h EuBCO films was not lower than that of in situ 6 h EuBCO films. The c-axis length of the as-grown EuBCO films grown under an ozone atmosphere showed 1.170 nm. It must be noted that the lowest surface resistance of EuBCO films was obtained by EuBCO films grown under the ozone atmosphere without any in situ annealing. We found that the growth of EuBCO films under the ozone atmosphere was good to dope oxygen in the films.