Selective growth of Au nanoparticles on PZT substrates by using a photochemical reaction

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We report the surface distribution of Au nanoparticles (NPs) grown on polarity-patterned ferroelectrics by using photochemical-reaction deposition. Polycrystalline lead zirconate titanate (PZT) was used as a ferroelectric substrate. The local polarization orientation on the surface was patterned by using atomic force microscopy (AFM). The Au NPs were grown by ultraviolet (UV) light exposure of the polarity-patterned PZT substrates while immersed in Au salt solutions. The wavelength dependence of the deposition of the NPs was investigated using UV band pass filters. The dimensions and the surface distribution of the NPs were measured by using AFM. For UV light without a filter, more NPs were formed on the +z polarity region than on the other regions. However, for UV light with wavelengths of 315 nm and 365 nm, we observed the selective deposition of NPs on +z polar domains. The NPs on the +z polar domains were denser and larger than those on the other non-polar regions. The average size of the NPs was ∼30 nm and the number density was ∼22/µm2. In addition, the electron affinity of the PZT was found to be ∼3.0 eV from scanning Kelvin probe microscopy measurements of the PZT film surface with the deposition of Au NPs. This study suggests the possibility of controlling the sizes and the positions of Au NPs on a surface by optimizing the UV wavelength and polarity patterning of the ferroelectrics.