LASRGAO4 SUBSTRATE GIVES ORIENTED CRYSTALLINE YBA2CU3O7-Y FILMS

As-grown YBa2Cu3O7-y (YBCO) thin films of 70 nm thickness have been prepared on LaSrGaO4 (001), (100), and (110) single-crystal substrates at 700-degrees-C using ArF laser ablation deposition. The c-axis oriented thin films with smooth surface morphology are obtained on LaSrGaO4 (001) and (100) substrates. The zero resistance temperatures (T(c)) of the films on the (001) and ( 100) substrates are 90.0 K, and 88.1 K, respectively. On the (110) substrate, (110) YBCO planes grow epitaxially. The resistance perpendicular to the c axis in this film is 1/3 of that parallel to the c axis, showing T(c perpendicular-to) = 85.9 K and T(c parallel-to) = 84.4 K, respectively. These results suggest that a LaSrGaO4 substrate having a low dielectric constant is an excellent substrate for the epitaxial growth and device application of high-T(c) YBa2Cu3O7-y superconducting films.