COMPARISON OF YBCO-FILMS PREPARED BY LASER ABLATION AND SPUTTERING

Two different preparation techniques, i.e. laser ablation and dc-sputtering have been applied for the production of thin films from YBa2Cu3O7 - x. Both techniques do not require postannealing steps, as the condensation of the superconducting film is done onto a hot substrate (600-780 °C) at high oxygen pressures (1-6 mbar). Besides the superconducting properties (Tc(R = 0) ≥ 90 K, jc(77 K) > 4 × 106 A/cm2) also the structural properties are very similar (single crystalline, c-axis oriented) as measured by ion channeling (χmin ≈ 5.5 %), x-ray scattering and TEM. The preparation methods require quite different process times, < 10 min for laser ablation compared to about one hour for sputtering. They yield different SEM-appearances of the surface: the sputtered surface is clean and smooth, but the laser oblated film shows in addition balls of 200 nm dia. The properties of films made by both techniques are compared and discussed in detail. In addition results on various buffer layers between YBCO and Si are presented. The interdiffusion of the various components have been analysed by RBS. Promising results have been obtained for buffer layers from ZrO2, where only little interdiffusion could be observed, resulting in good superconducting YBCO-overlayers. © 1990.