COMPARISON OF THIN-FILMS OF YBA2CU3O7-X DEPOSITED BY PHYSICAL (LASER ABLATION) AND CHEMICAL (OMCVD) METHODS FOR DEVICE APPLICATIONS

We report here the results of a comparative investigation of the perfection of epilayers of high temperature superconducting (HTS) YBa2Cu3O7-x (YBCO) films deposited by pulsed laser deposition (PLD) and organometallic chemical vapor deposition (OMCVD) methods. The substrates used in the present investigation are MgO, SrTiO3, Al2O3 (sapphire) covered in situ with Y2O3 stabilized ZrO2 (YSZ) on the (1102BAR) plane by either OMCVD or PLD, and MgO covered by YSZ buffer layers produced by OMCVD. It was found that on almost all substrates and/or buffer layers, the YBCO films have critical temperature (T(c)) close to 90 K and critical current density (J(c)) in excess of 10(6) A/cm2 at 77 K. The largest differences between the various films were found in (1) in-plane ordering as determined by X-ray diffraction scans, which relates directly with Ic but not with T(c), and (2) the roughness of the film surface as determined by Dectak measurements, scanning tunneling microscopy (STM) and scanning electron microscopy (SEM). Generally the films obtained by PLD are smoother and have slightly better in-plane ordering than those produced by OMCVD; however, both methods allow the preparation of YBCO films with the highest values of T(c) and J(c) reported in the literature.