Noble Metal Nanocluster Formation in Epitaxial Perovskite Thin Films

[Image: see text] We studied the synthesis of nanocomposite materials consisting of noble metal clusters embedded in an oxide semiconductor matrix. The embedded nanostructures form in a simple self-organized single-step growth process. The primary interest is in developing materials for photo-electrochemical energy conversion where spatially inhomogeneous band structures can enhance photogenerated charge separation and carrier extraction from a semiconductor. We show that spontaneous segregation of metallic Ir occurs during the initial growth of an Ir:SrTiO(3) thin film. Cross-sectional transmission electron microscopy suggests that the nanoscale Ir clusters are epitaxial with the host lattice, and their presence is not detectable by surface morphology measurements.