A New Emission Mechanism for Island-Metal-Film-Based Electron Sources


Zhan F, Li Z, Wang Y, Yang W, Wei X. A New Emission Mechanism for Island-Metal-Film-Based Electron Sources. IEEE Transactions on Electron Devices. 2020;67:5119-5124.


Electron emission (EE) from electron sources based on island metal films (IMFs) was mainly attributed to field emission or thermionic emission from IMFs. Here, we propose a new mechanism of EE from IMF-based sources, namely, EE from horizontal tunneling junctions formed in the substrate. The devices with and without IMFs fabricated on silicon oxide substrates are found to exhibit similar EE properties, while the island-metal-film-based devices fabricated on Si3N4/Si substrate show no EE. The comparative results indicate that EE originates from the underlying silicon oxide substrate that was ignored in previous mechanisms, but not from IMFs. EE from the devices is thought to be generated from horizontal tunneling junctions in electroformed silicon oxide substrate due to the rupture of conducting filaments. Even though metal island films are not the origin of EE, they can greatly decrease the forming voltage of the devices. The insights into the emission mechanism are helpful for optimizing the electron source performances.