Surface morphology of pulsed laser deposited YBa2Cu3O7-δand NdBa2Cu3O7-δthin films on SrTiO3substrates

A morphological study of on-axis NdBa 2 Cu 3 O 7-δ (NBCO) and on-axis and off-axis YBa 2 Cu 3 O 7-δ (YBCO) pulsed laser deposited films is presented. YBCO films deposited in on-axis geometry exhibit a high droplet density of about 10 7 cm -2 and three-dimensional features probably related to stoichiometric outgrowths. YBCO off-axis films present a surface with very low droplet density (about 10 5 cm -2 ) and the density of other defects like holes and stoichiometric outgrowths is less than 10 3 cm -2 . In spite of a higher droplet density with respect to off-axis YBCO (about 10 6 cm -2 ), NBCO films have a surface without other defects. Moreover, the NBCO film morphology is almost insensitive to variation in the deposition conditions. Atomic force microscopy analysis revealed that YBCO off-axis deposited films grow in a spiral growth mode, while NBCO films exhibit a texture, probably due to an initial two-dimensional growth. The YBCO off-axis and NBCO films have a mean roughness in a 10 × 10 µm 2 area of about 7.5 and 1.45 nm, respectively.