Growth and ozone oxidation of the SrCuO2/CaCuO2 superlattices

We have investigated the growth and the oxidation of the SrCuO2/CaCuO2, infinite-layer superlattice films to obtain artificially layered hypothetical high-T-c superconductors of SrCuO2+delta/CaCuO2, in which the excess oxygen is incorporated selectively into the Sr-Cu-O layers. The pulsed laser deposition equipped with in situ RHEED monitoring system was employed to grow thin film samples, In the case of single-layer films, the SrCuO2+delta films cooled in ozone were found to have excess oxygen and exhibit weak metallic electrical transport property, while the CaCuO2 films maintained the infinite-layer structure after cooling in ozone. On the other hand, the superlattice films cooled in ozone had either the SrCuO2/CaCuO2 infinite-layer structure or the SrCuO2+delta/CaCuO2+delta,, structure with the excess oxygen in both the Sr-Cu-O and Ca-Cu-O layers, depending on the thickness of the Ca-Cu-O layer. The desired superlattice structure was not obtained probably because of the structural distortion accompanied by the incorporation of the excess oxygen. (C) 1997 Elsevier Science B.V.