COMPARISON OF HETEROEPITAXIAL YBA2CU3O7-DELTA AND TIO2 THIN-FILM GROWTH

The growth of heteroepitaxial YBa2Cu3O7-delta and TiO2 thin films has been investigated as a function of deposition rate, film thickness, an d deposition temperature. In spite of the fact that the two materials are grown at very different rates and undercoolings, the films are fou nd to have similar growth mechanisms and dependences on film thickness and deposition temperature. Both types of films were found to have an island growth morphology, as shown by STM and AFM. The diameter of th e islands was found to increase with the film thickness through a powe r law dependence. It is shown that this is not the result of a grain g rowth mechanism, but is consistent with that predicted for a coarsenin g mechanism. The density of the islands decreased exponentially with i ncreasing substrate temperature. The temperature dependence is consist ent With those of homogeneous nucleation and of a diffusion-controlled process. The similar characteristics of the films of these two differ ent materials suggest that YBa2Cu3O7-delta may be useful as a model sy stem for studying heteroepitaxial oxide film growth.