Semitransparent Conductive Thin Porous Au Films on a Thiol-containing Primer Layer formed from Au Nanoparticle Ink

We demonstrated that thin porous Au films showing semi-transparency in the region of visible light and electric conductivity were prepared by spincoating an alpha-terpineol ink containing decanethiol-passivated Au nanoparticles onto silica and silicon substrates modified with 3-mercaptopropyltriethoxysilane and subsequent annealing for sintering the Au nanoparticles. A thin film of the alpha-terpineol ink was transformed to droplets on unmodified silica and silicon substrates by dewetting after spincoating, while it was changed to a thin porous film on the modified substrates by suppressing a progress of dewetting. The porous structure remained after sintering at 300 degrees C, resulting in the formation of semitransparent and conductive thin porous Au films with a transmittance of about 40 % in the visible light region and a surface resistivity of 10(-2) - 10(-3) Omega/square. We also demonstrated that the thin porous Au film was available as a wet etching mask for silicon microprocessing using a hydrogen fluoride (HF) aqueous solution.