Transmission electron microscopy study of the interface of Bi2Sr2CaCu2O8+δ thin films on (110) oriented SrTiO3 substrates

Thin films of Bi2Sr2CaCu2O8+delta on (1 1 0) oriented SrTiO3 substrates have been investigated by high resolution electron microscopy. Two growth orientations were observed: domains with the c-axis oriented perpendicular to the substrate surface and domains inclined with the c-axis almost parallel to the [1 0 0]s and [0 1 0]s substrate directions. For both growth orientations in-plane alignment with the (1 1 0)s plane was achieved. The c-axis domains show a high crystalline quality and regular stacking of the 2212 phase. Investigations of the substrate-him interface revealed that the first layer at the interface of the c-axis oriented grains is the Bi-O layer. The tilted domains exhibit stacking faults reading to the formation of polymorphic structures, The substrate surface below the tilted grains is found to be rough and consisting of (1 0 0)s and (0 1 0)s facets. The growth of the tilted domains appears to be triggered by nucleation at these (1 0 0)s and (0 1 0)s facets of the SrTiO3 substrate. In contrast, c-axis growth is found on a smooth substrate surface. (C) 1998 Elsevier Science B.V. All rights reserved.