Site Selective Arrangement of Gold Nanoparticles on Aminosilane Self-Assembled Monolayer Modified Indium Tin Oxide

Abstract

Nanoparticles and nanowires process physical properties that are different from their bulk counterparts, due to their small size. This leads to the observation of phenomena such as energy, charge, and conductance quantization which might constitute the basis for future electronic devices. The use of nanoparticles in device structures requires precise control of their size and position as well as the ability to electrically connect them to the macroscopic world. In this paper, we provide a convenient method for fabricating highly controlled arrays of gold nanoparticles on an indium tin oxide (ITO) substrate by combining atomic force microscope (AFM) lithography and self-assembled monolayers (SAMs). Our main methodology was to fabricate nanopatterns on ITO using amino group and methyl group terminated self-assembled monolayers, at different surface locations. These nanopatterns were then used to guide the assembly of gold nanoparticles according to their different affinities for amino and methyl groups. AFM lithography was employed to induce a localized degradation of the methyl SAM on the ITO substrate in order to control the amino SAM-covering area for nanoparticle adsorption. The amino SAM was formed on the degraded regions by the self-assembly technique. Gold nanoparticles selectively assembled at the AFM tip-defined amino regions, forming precisely positioned nanoparticle arrays while preventing defects of SAMs and dehydration.