Growth of thin ZnO films from aqueous solutions in the presence of PMAA-graft-PEO copolymers

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. Films grown at different growth rates were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Films that were obtained at high growth rates exhibit canyon-like morphology, whereas low growth rates yield uniform films with low surface roughness. According to X-ray Photoelectron Spectroscopy (XPS) a part of the polymer remains attached to the precipitated particles and can be removed by pyrolysis at about 723 K.