AFM observation of as-grown ( [formula omitted]) Bi-2223 and ( [formula omitted]) Y-123 thin films by MOCVD

Abstract

In high temperature superconductors (HTS) the coherence length along non- c-axis directions is longer. This feature can be useful when designing electronics devices based on HTS. Therefore, growth and characterization of non- c-axis oriented thin HTS films is of great interest. In this paper we present our comparative results on preparation by MOCVD and characterization by atomic force microscopy, X-ray diffraction and transport measurements of as-grown (1 1 9) Bi-2223 and (1 0 3) Y-123 thin films on (1 1 0) SrTiO 3. The films have shown the same type of surface morphology (grains with mountain-range shape, aligned in parallel chains to the [0 0 1] substrate’s azimuth). This morphology is the result of the orientation relationship between the (1 1 9) Bi-2223 or (1 0 3) Y-123 and (1 1 0) SrTiO 3. The transport measurements with temperature revealed strong anisotropy of the films in the normal state region when the measuring current has been applied in-plane, parallel and perpendicular to the edges (from the basal plane) of the mountain-range grains. Higher values for T c0 have been obtained for the Y-123 films (42 K) than for the Bi-2223 ones (31 K). The both films are as-grown and non-oxygenated ones.