GROWTH AND SURFACE MORPHOLOGY OF LASER ABLATED YBaCuO FILMS ANALYSED BY SEM

For the application of HTSC thin films in microelectronics, smooth films without surface particles are required especially considering devices involving multilayer systems or sub-micron structures. Therefore, we investigated the dependence of the surface morphology particularly the general surface roughness, the existence of outgrowths, and the density of droplets on the preparation conditions under the requirement of retaining good superconducting properties. The variation of the oxygen partial pressure, the substrate temperature, or the deposition rate while keeping all other parameters constant strongly influences the roughness and outgrowing of particles. We further report on the structure of the droplets. Their density and size depend sensitively on the laser-target-substrate geometry, the deposition rate per pulse, the target density, and the film thickness. The study reveals that deposition parameters exist which enable us to obtain good superconducting films with smooth surfaces and a droplet density below 1/(100 mu m)(2) suitable for application.