Selective deposition of gold particles on dip-pen nanolithography patterns on silicon dioxide surfaces

We report a novel platform to perform selective deposition of gold nanoparticles on dip-pen nanolithographic patterns on SiO₂ surfaces. An "inked" atomic force microscope (AFM) tip was adopted to deposit 2.2 mM organic N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS) molecules in nanopatterns through a water meniscus onto a SiO₂ substrate under ambient conditions; the molecules act as linkers for the selective deposition of gold nanoparticles on the SiO₂ surface. Conditions for dip-pen nanolithography of organic nanopatterns of AEAPTMS were investigated. In addition, gold nanoparticles with negatively-charged citrate surfaces were deposited selectively on top of the organic patterns. X-ray photoelectron spectroscopy was then used to evaluate the presence of gold nanoparticles on the SiO₂ surface. Lateral force microscopy was utilized to differentiate the surface between oxidized semiconductors and patterned areas with monolayer of AEAPTMS. Linewidths down to 60nm have been successfully achieved by this method.