High rate deposition of 5 μm thick YBa2Cu3O7 films using the BaF2 ex-situ post annealing process

We have investgated the crystallization of thick YBCO films under various annealing conditions. The films were deposited by high-rate co-evaporation of Y, Cu and BaF2 onto room-temperature SrTiO3 substrates at rates exceeding 10 nm/s. TEM microscopy was performed to establish the microscopic structure of partially processed films and help elucidate the growth mechanism. In-situ resistivity measurements were used to monitor the crystallization of the YBCO films during the annealing process. Resistivity measurements and TEM microscopy of samples at different stages of the film growth are compared. Our results indicate that, in addition to oxygen partial pressure, water vapor pressure is an important parameter which defines the dynamics of film growth and crystallization. 5 mu m thick films with J(c) > 2 x 10(5) A/cm(2) (1 T H parallel to c) have been fabricated.