High Quality YBa2Cu3O7-x Superconducting Thin Films Grown by MOCVD

YBCO thin films have been grown by Metal Organic Chemical Vapour Deposition in ;I cold wall type reactor. The 0-diketonates of yttrium, barium and copper are used as precursors. Filrna have bcen deposited on (001 I MgO and (012) LaA103 single crystalline substrates. The morphology is very dependant on thc gas p h a x composition. Different oxygen partial pressures have been investigated. An increasing oxygen partial prcasul-c at a fixed deposition temperature is found to increase the growth rate and to promote the growth of a-axis grams (gmlns with the c axis parallel lo the substrate's surface). In our standard deposition condit~ons. T substrate holdcr = 575 O C . P Total = 5 Torr, and P o 2 = 2 Torr, high qua l~ ty films are obtained, exhibiting Tc 9 1 K (10%-YO V ol' the resistive transition) and Jc (77K) 5.106 A/cm2. A trilayer htructure YBCO/Y?O3/YBCO ( ~ ~ I I ~ ~ I O O A I ~ O O A ) h i1 been grown on LaA103 substrate, with the epitaxial relationship : ( 0 0 1 ) y ~ c o I/ <100> i ) r <010> ( 0 0 1 ) ~ ~ ~ ~ . No misorientations have been found in the (a.b) plane. The trilayer exhihits a sharp supcrcoi~ductiiig transition (ATc = 0.4 K), with Tc = 82.5 K, and Jc(77 K) lo6 .4/crn2.