Infinite-layer (Ca,Sr)CuO 2 films grown by MOCVD: surface morphology and structural studies

Abstract

For fabrication of sandwich-type SIS Josephson junctions of HTS, c-axis stacked layers should have smooth and uniform surface. In this regard, control of layers morphology is essential. In the present work, infinite-layer Sr x Ca 1− x CuO 2, 0< x<1 thin films, to be potentially used as the insulator in SIS structures, have been grown by MOCVD at 750–800 °C. Higher temperatures promote growth of the films surface with lower roughness. Furthermore, roughness (arithmetic (Ra) and root mean square (Rms) values) are minimum for x=0.5 and the films show a square type uniform morphology. Films are in-plane aligned, as revealed by AFM. Up to x=0.5, films consist of infinite-layer single phase and at higher values for x, an unknown phase occurs and its amount is increasing, while the concentration of the infinite-layer phase is decreasing. Electrical resistance of the as-grown film was above 10 MΩ.