Development and characterization of crack-initiated and electromigrated tunnelling nanogap junctions

Nanogap junctions consist of two electrically conducting tips separated by a nanometric gap (nanogap). A tunnelling current can be detected in sub-3nm nanogaps. They enable a variety of applications, including biomolecular detection, molecular electronics, nano-photonics and plasmonics. In this Master Thesis project a new approach to fabricate nanogap junctions is developed. The process exploits the electromigration of gold ligaments formed through the crack-defined break-junctions (CDBJs) methodology. The nanometric cross-section of the gold ligaments allow adopting a simple electromigration process, which does not require feedback loops. In addition, ligaments are suspended, thus avoiding the common issue of debris generation in the vicinity of the gap during electromigration. The lack of feedback systems opens up the possibility to use this method to electromigrate several devices in a parallel fashion and to enable the fabrication of large arrays of tunnelling nanogap junctions.