Selective Growth of Fe2O3 Nanoparticles and Islands on Au(111)

Selective growth of well-defined alpha-Fe2O3 structures was achieved on a Au(111) surface and characterized using X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). Although oxidation of Fe particles on Au(111) with molecular O-2 at room temperature forms FeO, Fe2O3 is prepared by oxidation of Fe particles on Au(111) with NO2 at an elevated temperature, as verified by XPS, based on the binding energy (BE) value of the Fe 2p(3/2) (710.9 eV) peak and atomic ratio of O and Fe similar to 1.5:1. STM images reveal that Fe2O3 adopted ordered three-dimensional structures on Au(111). Although the general morphology of the Fe2O3 structures on Au(111) depends on the cove rage, varying from nanoparticles at low coverage to islands at high coverage, all of these Fe2O3 structures have nearly identical heights of 5-6 angstrom at all coverages. The surface structures of the Fe2O3 are all consistent with an O-terminated alpha-Fe2O3(0001), showing a hexagonal unit cell with a lattice constant of similar to 3 angstrom in atomically resolved STM images.