Electromigrated nanogaps: A review on the fabrications and applications

Electromigration-a critical failure mode of metal interconnects in integrated circuits-has been exploited for constructing nanometer-sized gaps (or nanogaps, less than a few nanometers) on metallic nanowires. Electromigrated nanogaps have been utilized extensively in the field of nanotechnology and have demonstrated to be an effective platform for electrically accessing small things such as molecules in a device fashion, establishing metal-molecule-metal junctions. These devices allow the study of the electronic transport phenomena through molecules and DNA. Furthermore, electromigrated nanogaps can read out incident electromagnetic fields as an antenna due to the plasmonic excitation on the surface, which is usually maximized in nanogaps. Moreover, structural changes caused by electromigration on metallic nanowires have been leveraged to create single-component resistive switching memories. In this review, we discuss the recent progress and challenges of electromigration methods for a nanogap creation as well as their applications for electronic devices (molecular/DNA devices and resistive switches), thermoelectric energy conversion devices, and photonic devices (nanoantennas).