Influences of additives on the formation of thin zno films on self-assembled monolayers

The deposition of homogeneous and adherent ZnO films on Si wafers by thermohydrolysis of zinc salts in aqueous solution is reported. Using a graft copolymer (polymethacrylic acid partially grafted with polyethyleneoxide side chains) homogeneous films of nanosized particles on Si wafers with self-assembled monolayers (SAMs) were obtained. The addition of the polyelectrolyte is necessary to suppress the formation of undesired, larger zincite crystals, which form inevitably otherwise. The deposition of films was investigated on surfaces, which were functionalized with mercapto- or sulfo-terminated SAMs, as well as on unfunctionalized substrates. The morphology of the films was characterized by light microscopy and atomic force microscopy. Only incomplete coverage of the substrate surface was achieved on SAMs with sulfo groups or on unfunctionalized surfaces, whereas complete coverage of the substrates was obtained after modification with mercapto functions.