Investigating Resistive Switching Mechanism in Niobium oxide Thin Film based Resistive Switches*

There is large interest in exploring various transition metal oxides for their potential applications in resistive random access memories (RRAM) with emphasis on understanding the switching mechanism. Niobium oxide as resistive switching device is believed to be valence change memory (VCM) mechanism, where oxygen vacancies are responsible for formation of conducting filament. However, in Nb-oxide based VCM devices, we observe metallic nature of conducting filament, made of Nb atoms, which is similar to redox based electrochemical metallization memory (ECM) mechanism. By tuning the current compliance, we are able to make point contact filament resulting in quantization of conductance which can be useful in multilevel storage applications. We correlate atomic structure, conductance and mechanism of formation of conducting filament which provides new insights in understanding the resistive switching mechanism.