Novel approach to microcrack-free thick YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films on r-cut sapphire buffered with CeO/sub 2/

Stoichiometric YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) films were fabricated by pulsed laser deposition on deliberately miscut Al/sub 2/O/sub 3/ (11_02) buffered with CeO/sub 2/. Atomic force microscopy observations demonstrated that 600 nm-thick YBCO films were microcrack-free. Characterization of the films revealed a porous morphology, consisting of interconnected islands and deep holes (pores). This feature is considered as one of the sources contributing to the strain-relieving mechanism responsible for the increase in film thickness without microcracking. We observed T/sub c/=90/spl plusmn/0.5 K, J/sub c/ (77.3 K, 0 T)=1.5-2.0/spl times/10/sup 6/ A/cm/sup 2/, and J/sub c/t (77.3 K, 0 T)/spl sim/120 A/cm. In addition, this new approach, using the deliberately miscut sapphire as a substrate for YBCO, is also applicable to other kinds of deposition techniques.