AFM Study on YBa2Cu3O7-y Thin Films by MOCVD using Liquid-state Sources

Abstract

The superconducting YBa2Cu3O7-y (YBCO) thin films were prepared on MgO (100) substrates with SrTiO3 (100) buffer layer by metalorganic chemical vapor deposition (MOCVD) using liquid-state sources. The obtained films with the thickness of about 1000A had critical temperatures which were equal to that on MgO substrate. However, these critical temperature rose as the film thickness of YBCO increased, and reached 91K at a thickness of about 2300A. From the atomic force microscopy (AFM) and transmission electron microscopy (TEM) image, the SrTiO3 (100) buffer layer grew in the form of grain. The grain boundary of the YBCO thin film originated from that of the SrTiO3 (100) buffer layer. It is expected that the control of the grain of the SrTiO3 buffer layer enable the control of the YBCO grain.