Comparative analysis of low-frequency noise based resistive switching phenomenon for filamentary and interfacial RRAM devices

We investigate the low-frequency noise (LFN) characteristics of resistive switching random access memory (RRAM) devices with metal–insulator–metal structures of TiN/Ti/TiO₂/TiN (filamentary) and TiN/Ti/TiO₂/HfO₂/TiN (interfacial). By comparing filamentary and interfacial RRAM devices, we stipulate guidelines for noise sources according to the resistance states or resistive switching mechanisms of RRAM device. In filamentary RRAM devices, the dominant noise source in the low resistance state is the localized oxygen vacancies, whereas the noise characteristics in the high resistance state represent a bulk effect. In interfacial RRAM devices, the noise characteristics in both resistance states represent the bulk effect. The physical mechanism of the multilevel cell operation is inferred by the I–V characteristics in both I_cc and V_reset control modes. Specifically, the changes in the structure of the conductive filament inside the switching layer can be confirmed through LFN measurement.