A transmission electron microscopic study of ceramic superconducting thin films prepared by laser deposition

Abstract

Many applications of the new high temperature ceramic superconductors require the materials to be prepared in a thin film form. The substrates play an essential role in the superconducting properties of these films. In order to optimize the critical temperatures and currents of the films and to search for new suitable substrates of desirable properties, it is important to understand the interfacial interaction between the films and the substrates. TEM studies of the cross-sectioned specimens are indispensable in providing such information.In this paper, we describe the microscopic structures of two types of Y-Ba-Cu-O thin films deposited on SrTiO3 substrates with a KrF excimer laser. The high-temperature-processed specimens are deposited at 450 C in vacuum and post-annealed for 1 hr at 900 C in an oxygen atmosphere. The low-temperature-processed specimens are deposited at 650 C in an oxygen pressure of 5 mTorr, and post-annealed for 3 hr at 450 C in an oxygen atmosphere.