Periodic structures of silicon are of interest in quantum-dot-based applications because of their unique optical and electronicproperties. We report on the fabrication of stable quasi-ordered Sinanocluster arrays on the moire of a hexagonal boron nitride (h-BN)monolayer on Ir(111). The h-BN monolayer promotes the growth ofregular Si nanoclusters at 130 K and electronically decouples the clustersfrom the underlying metallic substrate. Using scanning tunnelingmicroscopy and spectroscopy, we have investigated the cluster bindingsites, their electronic structure, and their thermal stability. Wefind that theclusters display a size-dependent bandgap and that they are stable up to577 K, after which cluster coalescence degrades the arrays.

With the goal to delevop the fabrication of a new type of Pt-nanoparticle carbon-support electrocatalyst, we investigate the carbon embedding of Pt cluster superlattices grown on the moire of a monolayer of hexagonal boron nitride (h-BN) on Ir(111). Our combined scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) study establishes conformal C embedding of the Pt clusters on h-BN/Ir(111) without deterioration of superlattice order, preferential and strong binding of the embedding carbon to the Pt clusters, and upon annealing the formation of a homogeneous amorphous carbon (a-C) matrix. There are indications that while the a-C matrix and the Pt clusters bind strongly to each other, upon annealing both weaken their binding to h-BN.