Interfacial depth profiling of superconducting high‐Tc mono‐ and multilayer structures by Auger electron spectroscopy

Abstract

AbstractSuperconducting YBa2Cu3O7 − x based multilayer structures with insulating NiO buffer layers have been prepared for application in microelectronic devices. For this, the reactive dc magnetron sputter technique has been used which enables YBaCuO/NiO/YBaCuO/SrTiO3 composite systems with relatively sharp interface transitions and small degradation effects in superconductivity to be produced. The interfacial diffusion effects and the changes in elemental composition of such multilayer systems and their metallic (Cu, Ag, and Au) overlayered cuprate–substrate components have been investigated by Auger electron spectroscopy (AES) depth profiling measurements before and after thermal annealing at temperatures between 100 and 700 °C. The experimental results presented here demonstrate that YBaCuO/NiO/YBaCuO multilayer structures are useful systems in superconducting devices where less interfacial reactions take place in a post‐annealing temperature range of around 250 °C. The diffusion coefficients and the activation energies of contact metals like copper, silver, and gold on YBaCuO layers have been determined from an Arrhenius plot. Transition temperature, Tc, measurements of post‐annealed metal overlayered YBa2Cu3O7 − x samples revealed only small degradation effects in Tc for all types of samples, especially for Cu and Au contacted superconductors.In addition, AES measurements have been performed on YBaCuO films, deposited by pulsed‐laser on buffered silicon substrates, with intermediate yttrium stabilized ZrO2 (YSZ) buffer layers of different thicknesses used as barriers against silicon diffusion, in order to obtain information about the efficiency of YSZ layers applied in superconducting microswitching elements.