Spatially Controlled Functionalization and Chemical Manipulation to Fabricate Two-Dimensional Arrays of Gold Nanoparticles onto Indium Tin Oxide

We demonstrate the formation of two-dimensional (2D) arrays of gold nanoparticles (AuNPs) by controlled functionalization in a regular linear fashion, on the basis of the self-assembly and vacuum ultraviolet (VUV) lithography approaches. An octadecyltrimethoxysilane (ODS) monolayer, self-assembled on an indium tin oxide (ITO) surface, was exposed to VUV light (172 nm) through a photomask to construct the linear pattern by photodegradation of the ODS monolayer. Subsequently, an aminopropyltriethoxysilane (APS) monolayer was deposited on VUV-exposed sites by chemical vapor deposition. The immobilization of AuNPs on amino-terminated sites is due to the electrostatic attraction between citrate-stabilized AuNPs and amino groups of the APS monolayer, while the methyl-terminated sites remain unexposed. The structural organization of AuNPs in an alternating linear fashion was demonstrated by scanning electron microscope (SEM) analysis. The X-ray photoelectron microscopy (XPS) measurements were performed to probe the self-assembly of ODS, the APS monolayer, photopatterning and AuNPs immobilization.