Influence of Ion Beam Mixing on the Growth of High Temperature Oxide Superconducting Thin Film

ABSTRACTThe superconducting properties of high temperature superconductor (HTS) thin films fabricated using the BaF2 process are dependent on the quality of the substrate used to grow these films. In order to maximize the lattice matching between the superconducting film and the substrate, we have used a YBa2Cu3O7, thin film deposited on <100> SrTiO3 as a template. The first film was prepared by co-evaporation of Y, BaF2 and Cu on <100> SrTiO3, followed by an anneal in wet oxygen at 850 C. This film showed a sharp transition at about 90 K. A thicker layer of about 5000 A was then deposited on top of this first 2000 film, using the same procedure. After the post anneal at 900 C, the transition took place at 82 K and no epitaxy of the second film was observed. Ion beam mixing at 400 C, using 400 keV O ions was done at the interface of the two films (the second one being not annealed). After the post anneal, the film displayed an improved Tc at 88K. Moreover, epitaxial growth was observed to take place at the ion mixed two-layer interface which was dose dependent. These results suggest that the homoepitaxy of the second layer on the first is interface limited and can be enhanced by ion mixing treatments.

Influence of Ion Beam Mixing on the Growth of High Temperature Oxide Superconducting Thin Film Academic Article