Scanning Probe Lithography of Self-Assembled N-(2-Aminoethyl)-3-aminopropyltrimethoxysilane Monolayers on SiO2 Surface

A new approach is introduced for the selective deposition of colloidal gold nanoparticles (AuNPs) onto the surface of unpatterned self-assembled monolayers (SAMs). The patterning of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS) SAMs is realized by local field-induced bond breaking using scanning probe lithography (SPL) on a thin SiO2 surface. Different tip/sample biases were investigated to determine the bond breaking efficiency of AEAPTMS SAMs. It was found that bond breaking efficiency was limited by tunneling current through the thin SiO2 film so that both the tip bias and the tip scanning speed play important roles. AuNPs with negatively charged citrate surfaces were selectively anchored onto the unpatterned area via electrostatic force between AEAPTMS SAMs and AuNPs. Single-digit numbers of AuNPs anchored onto unpatterned AEAPTMS SAMs were demonstrated.