XPS Study of Bi-Sr-Ca-Cu-O Superconducting Thin Films Prepared by the rf-Sputtering Method

Abstract

The charge fluctuation of Cu ions in the superconducting Bi-Sr-Ca-Cu-O system was investigated using X-ray photoemission spectroscopy in thin films prepared by the rf-sputtering method. It was confirmed that long-time annealing was essential to form the high- T c phase in thin films of this Bi-Sr-Ca-Cu-O system. From the peak decompositions of the Cu 2p 3/2 core-level spectra obtained after Ar ion etching, the content ratio of the Cu 2+ state to the Cu + state was found to increase with an increase of the high- T c phase content in the films.