Interfacial strain reliefs in epitaxial YBa_2Cu_3O_(7- delta ) thin films grown on SrTiO_3 buffered MgO substrates

摘要

High quality YBa_2Cu_3O_(7- delta ) (YBCO) epitaxial thin films grown on MgO substrate with a strain-relieved SrTiO_3 (STO) buffer layer have been investigated by Rutherford backscattering spectrometry (RBS), ion channeling and high resolution cross sectional transmission electron microscopy (XTEM). The in-situ growth of STO buffer layer along with the YBCO films was carried out by pulsed laser ablation. In this work, minimum yield of channeling measurements have shown that a very thin STO buffer layer is sufficient to grow highly crystalline YBCO thin films on MgO substrates. TEM studies showed that the STO layers were strain-relieved by an array of periodic edge dislocations. The YBCO films on STO buffer, as in those grown directly on an STO substrate, evolved from a strained layer to a largely dislocation free area.