Patterned growth of Au nanoparticles on polycrystalline lead zirconate titanate surfaces

We report the patterned growth of Au nanoparticles (NPs) on polarity-patterned polycrystalline lead zirconate titanate (PZT) as a template through photochemical reaction. The photochemical deposition of the Au NPs includes ultraviolet (UV) light illumination of the patterned PZT while immersed in a HAuCl4 solution. In particular, the influence of the UV wavelength, and the influence of the solution with the stabilizer and reducer on the growth selectivity of the Au NPs on the polarity-patterned regions was investigated. For a UV light of 365 nm wavelength, corresponding to a band-gap excitation of the PZT, more Au NPs were deposited on the + z polar region than on the other non-polar regions. However, no deposition of the Au NPs was observed for UV light wave-lengths longer than - 365 nm. When ascorbic acid (AA) as a reducer and cetyl-trimethylammonium bromide (CTAB) as a stabilizer were added to the HAuCl4 solution, the Au NPs on the + z polar region were observed to be deposited with a UV light of 435 nm, which is larger than the optical band gap wavelength of the PZT. Also, the growth selectivity and size uniformity on the + z region was significantly improved. These results could be due to the defect-induced photo-excitation of electrons and enhanced reduction process of Au+ ions by adding the reducer and the stabilizer in the photo-chemical process. This study suggests the possibility of the patterned growth of Au NPs on a ferroelectric surface through polarity patterning and photochemical reaction by optimizing the UV wavelength and employing reduction potential agents in a metal salt solution.