RESUMO
SrRuO(3) (SRO) thin films grown on (001)(p) (p = pseudocubic) oriented LaAlO(3) (LAO) by pulsed laser deposition have been characterized using transmission electron microscopy. Observations along the 100(p) directions suggests that although the SRO layer maintains a pseudocube-to-pseudocube orientation relationship with the underlying LAO substrate, it has a ferroelastic domain structure associated with a transformation on cooling to room temperature to an orthorhombic Pbnm phase (a(-)a(-)c(+) Glazer tilt system). In addition, extra diffraction spots located at +/-1/6(ooo)(p) and +/-1/3(ooo)(p) (where ;o' indicates an index with an odd number) positions were obtained in 110(p) zone-axis diffraction patterns. These were attributed to the existence of high-density twins on {111}(p) pseudocubic planes within the SrRuO(3) films rather than to more conventional mechanisms for the generation of superstructure reflections.
RESUMO
In the Ge on Si model heteroepitaxial system, metal patterns on the silicon surface provide unprecedented control over the morphology of highly ordered Ge islands. Island shape including nanorods and truncated pyramids is set by the metal species and substrate orientation. Analysis of island faceting elucidates the prominent role of the metal in promoting growth of preferred facet orientations while investigations of island composition and structure reveal the importance of Si-Ge intermixing in island evolution. These effects reflect a remarkable combination of metal-mediated growth phenomena that may be exploited to tailor the functionality of island arrays in heteroepitaxial systems.
