Preferential dewetting of gold thin films on single walled carbon nanotubes to produce nanogap electrodes

Abstract

The morphological evolutions of Au films deposited onto (3-mercaptopropyl)trimethoxysilane (MPTMS) treated substrates with a single walled carbon nanotube (SWNT) coating were investigated during thermal annealing. The dewetting of Au films, which initiated on SWNT surfaces, formed nanosize slits along SWNTs during annealing at 150 °C for 300 s. In situ measurements of film sheet resistances and subsequent analysis revealed that the activation energy of Au films for dewetting was as low as 0.36 eV, which was much lower than that of Au films (0.43 eV) deposited on the substrate without a SWNT layer. Based on the preferential dewetting behavior of Au films on SWNTs, a novel fabrication process was devised involving dielectrophoretic deposition of SWNTs and conventional micromachining to provide nanogap electrodes. Finally, nanogap electrodes with a sub-50 nm inter-electrode spacing were successfully fabricated.