Nanoparticle-assisted Frenkel-Poole emission in two-terminal charging-controlled memory devices based on Si-rich silicon nitride thin films

Silicon nanoparticle (Si-NP)-embedded silicon nitride (Si3N4) thin films have been synthesized by implantation of Si ions into Si3N4 thin films followed by high-temperature thermal annealing. With different implant dosage of Si ions, the concentration of Si-NPs has been varied in the Si3N4 matrix. By forming an Al/Si-NP-embedded Si3N4/p-Si structure, memory behavior was observed through charging-caused modulation in the device current. The current-voltage measurements were then conducted to study the carrier transport mechanism and thus to understand the origin of charging-induced variation in device resistance. It was found that the current exhibited a hopping-based conduction mechanism at low electric field. While at high electric field, a Frenkel-Poole (F-P) emission was found to dominate the current conduction. As a result, the charging-caused electron trapping under positive voltage in Si-NPs of the nitride film enhances the F-P emission, leading to a significant reduction in resistance. However, negative voltage-caused hole trapping suppresses the current conduction. The two-terminal devices based on such Si-NP-embedded Si3N4 thin films are promising to be used as charging-controlled memory devices.