Resistance transition in metal oxides induced by electronic threshold switching

Metal oxides can display resistance transition by the application of suitable electrical pulses, and this behavior is exploited for the development of resistive-switching memory devices. Here we report time-resolved electrical measurements demonstrating that the transition from the insulating to the metallic-conductivity state in NiO is first triggered by a threshold switching, i.e., an electronic transition to a highly conductive state typically observed in disordered semiconductors. Evidence for the possibility of subnanosecond transitions to low resistance is shown. Numerical simulations of threshold switching and Joule heating are finally presented, highlighting the role of the parasitic capacitance in the set transition.