AFM Study on YBa_2Cu_3O_(7-y) Thin Films by MOCVD using Liquid-state Sources

摘要

The superconducting YBa_2Cu_3O_(7-y) (YBCO) thin films were prepared on MgO (100) substrates with SrTiO_3 (100) buffer layer by metalorganic chemical vapor deposition (MOCVD) using liquid-statesources. 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 SrTiO_3 (100) buffer layer grew in the form of grain. The grain boundary of the YBCO thin film originated from that of the SrTiO_3 (100) buffer layer. It is expected that the control of the grain of the SrTiO_3 buffer layer enable the control of the YBCO grain.