Origin of tri-state resistive switching characteristics in SiCN thin films for high-temperature ReRAM applications

In the present work, the resistive switching (RS) properties of Ag/SiCN/Pt and W/SiCN/Pt devices having electrochemically active (Ag) and inactive (W) top electrodes have been systematically investigated. Both devices revealed stable and reproducible bipolar resistive switching characteristics. The W/SiCN/Pt device exhibits two-state resistive switching behavior, i.e., low resistance state (LRS) and high resistance state (HRS), whereas the Ag/SiCN/Pt device shows tri-state RS characteristics [LRS, intermediate resistance state, and HRS)]. The two resistance state RS characteristics of the W/SiCN/Pt device were ascribed to conduction path formation/rupture via electron trapping/de-trapping in nitride-related traps. However, the tri-state RS behavior of the Ag/SiCN/Pt device could be attributed to conduction path formation via electron trapping in nitride-related traps followed by an additional Ag filament growth between the top and bottom electrodes. The origin of tri-state switching in the Ag/SiCN/Pt device and Ag filament formation were well explained by a conceptual model and the temperature and cell area dependence of the resistance measurement. The Ag/SiCN/Pt device exhibits good reliable properties such as endurance of ∼105 cycles and long retention time ∼105 s at a high temperature of 200 °C. This comprehensive study suggests that nonvolatile multi-level (three-level) resistive switching in the SiCN-based device can be achieved by the formation of different types of conducting filaments sequentially and the Ag/SiCN/Pt device could be capable of futuristic multi-bit storage resistive random access memory which can operate at high temperature.