Improvement of Surface Morphology of Bi2Sr2CaCu2Ox Thin Films by using Nano-structured SrTiO3 Thin Films

Abstract

Surface morphology of Bi2Sr2CaCu2Ox (BSCCO) thin films prepared by metalorganic decomposition (MOD) method is successfully improved by using nano-structured SrTiO3 (STO) buffer layer prepared by MOD method. The nano-structured STO thin films were obtained by 2-step thermal treatment at 870°C for 2 hours followed by high temperature of 1000°C in O2 atmosphere for 1 hour. In the case of BSCCO thin films on conventional STO substrates, many islands consist of additional phases and large-size steps were observed. In contrast, segregations are extremely suppressed, and terrace structures with a-b plane of BSCCO were clearly observed. The BSCCO thin films on the nano-structured STO showed a critical temperature of 80 K. This result indicates that a control of nucleation is one of the most important factors to obtained high quality thin films in the case of hetero-epitaxy.