title: The optical properties of vertically aligned ZnO nanowires deposited using a dimethylzinc adduct.
abstract: The optical properties of zinc oxide nanowires are critically influenced by the growth process. Herein, we describe a metal-organic chemical vapour deposition (MOCVD) process for the growth of ZnO nanowires with improved optical properties. A tetrahydrofuran adduct is used to control the reactivity of dimethylzinc to enable this. Vertically aligned zinc oxide nanowires have been grown on Si(111) substrates by liquid injection MOCVD, using a solution of [Me(2)Zn(tetrahydrofuran)] in the presence of oxygen. The ZnO morphology becomes nanowire-like in a narrow temperature range centred about 500 degrees C. Above and below this temperature range, the ZnO is deposited in the form of polycrystalline films. The ZnO nanowires grow from a polycrystalline nucleation layer, with the (0002) c-axis parallel to the Si[111] substrate orientation. High-resolution electron microscopy reveals a highly crystalline nanowire microstructure. Resonance enhanced ultraviolet Raman spectroscopy shows that the ratio of first- and second-order longitudinal optic modes is commensurate with electron-phonon coupling effects observed previously in ZnO nanostructures. Photoluminescence exhibits intense near band-edge emission with a full width at half-maximum of 110 meV at room temperature and shows negligible defect-related visible emission.
authors.affiliation: Department of Chemistry, University of Liverpool, Liverpool, UK.
authors.forename: K
authors.initials: K
authors.lastname: Black
authors.forename: A C
authors.initials: AC
authors.lastname: Jones
authors.forename: I
authors.initials: I
authors.lastname: Alexandrou
authors.forename: P N
authors.initials: PN
authors.lastname: Heys
authors.forename: P R
authors.initials: PR
authors.lastname: Chalker