MICROSTRUCTURAL STUDY OF YTTRIA-STABILIZED ZIRCONIA BUFFERED SAPPHIREFOR YBA2CU3O7-DELTA THIN-FILMS

Yttria stabilized zirconia (YSZ) buffer layers were grown by rf-magnet ron sputtering on the r(<1(1)over bar 02>) plane of sapphire for YBa2C u3O7-delta(YBCO) thin film deposition. Microstructural changes of YSZ buffer layers grown using different sputtering conditions (5, 10, and 20 mTorr; Ar/O-2 gas mix ratio of 9:1 and 1:1) were monitored by atomi c force microscopy (AFM). Films grown using a lower oxygen partial pre ssure (5 mTorr) and a higher Ar/O-2 ratio (9:1) showed smooth surface morphology and the average surface roughness increased with an increas e in oxygen partial pressure. YBCO films in situ grown by pulsed laser deposition on sapphire with a YSZ buffer layer deposited using optimi zed sputtering parameters (5 mTorr gas pressure, 9:1 Ar/O-2 ratio) yie lded the highest critical density, J(c) approximate to 4.5x10(6) A cm( -2) at 77 K. An excellent correlation between microstructure and J(c) has been found and AFM has proved to be important for the study of the microstructure of films. (C) 1996 American Institute of Physics.