Fabrication of controllably variable sub-100 nm gaps in silver nanowires by photothermal-induced stress.

Abstract

A technique to fabricate nanogaps with controllably variable gap width in silver (Ag) nanowires (NWs) by photothermal-induced stress utilizing a focused continuous-wave laser (532nm) is presented. For the case of an Ag NW on gold thin film, a gap width starting from ∼20 nm is achieved with a critical minimum power (CMP) of about 160mW, whereas in the case of an Ag NW placed on top of a zinc oxide NW, the attained gap width is as small as a few nm (<10 nm) with a CMP of only ∼100 mW. In both cases, the CMP is much lower as compared to the required CMP (∼280 mW) for an Ag NW placed on a bare silica substrate. The photothermal-induced stress combined with Rayleigh instability, melting, and sublimation of Ag aids in breaking the Ag NW. In particular, the former one plays a key role in attaining an extremely narrow gap. This technique to fabricate sub-100nm nanogaps in metal NWs can be extensively implemented in fabrication and maintenance of nanomechanical, nanoplasmonic, and nanoelectronic devices.