Growth and structure of YBa2Cu3O7−δ thin films studied by scanning tunnelling microscopy and electron microscopy

Abstract The growth, surface and bulk structure of YBa 2 Cu 3 O 7− δ (YBCO) thin films have been studied by X-ray diffraction, scanning tunnelling microscopy and transmission electron microscopy. The films have been grown by pulsed laser deposition on MgO(001) crystal faces and novel Mg 2 TiO 4 (001) spinel layers. Using the thickness-gradient technique, different growth stages have been obtained simultaneously on a single substrate. Depending on the substrate temperature, YBCO(001), YBCO(100) and YBCO(103)–(110) growth structures have been detected. The film growth in the (001) orientation is characterized by spiral growth patterns, whereas growth in the (100) and (103)–(110) orientations show slab-like and platelet structures respectively.