Interdiffusion effects in high- Tc superconducting structures by Auger electron spectroscopy

Abstract

Microelectronic applications of high- T c superconducting multilayers with intermediate buffer layers require superconducting films with high critical current densities, j c , and uniform properties over the entire surface of interfacial regions. YBa 2Cu 3O 7− x multilayer composite samples, buffered with polycrystalline NiO films, were produced by reactive magnetron sputtering on SrTiO 3 substrates. The interfacial diffusion phenomena, the thermal damage and the changes in elemental composition of such superconducting multilayer systems, e.g. Y-Ba-Cu-O/NiO/Y-Ba-Cu-O/SrTiO 3, have been investigated by Auger electron spectroscopy (AES) depth profiling measurements before and after thermal annealing at temperatures between 125 and 625 °C. In addition, AES measurements were carried out on post-annealed YBa 2Cu 3O 7− x films deposited on pure and NiO buffered silicon substrates to obtain information about the interdiffusion effects of possible NiO barrier layers applied as protection against Si diffusion. The experimental results presented here demonstrate that YBa 2Cu 3O 7− x /NiO/YBa 2Cu 3O 7− x multilayer structures are useful systems in superconducting devices where less interfacial reactions take place in a post-annealing temperature range around 250 °C.