Conducting nanofilaments formed by oxygen vacancy migration in Ti/TiO2/TiN/MgO memristive device

High-quality TiN and TiO2 thin films were grown on MgO(100) substrate by plasma-assisted molecule beam epitaxy. X-ray photoelectron spectroscopy and x-ray diffraction studies indicate that the films are single phase. The memory cell composed of Ti/TiO2/TiN/MgO showed a bistable bipolar resistive switching behavior with either electrode grounded. The nature of the bipolar resistive switching phenomenon could derive from the formation and annihilation of filaments induced by oxygen vacancy and oxygen ion migration near/at the bias-applied electrode. In addition, a simple calculation of the filamentary resistivity in model might indicate that different devices made by TiO2 thin films with different phases might share the similar resistive switching mechanism.