Conductivity switching characteristics and reset currents in NiO films

Conductivity switching phenomena controlled by external voltages have been investigated for various NiO films deposited by dc reactive sputtering methods. $\mathrm{Pt}∕\mathrm{Ni}\mathrm{O}∕\mathrm{Pt}$ capacitor structures with top electrodes of different diameters have showed increasing off-state current with the diameter of a top electrode and nearly the same on-state current independent of the diameter. Local conductivity switching behaviors have been observed in a series structure consisting of two $\mathrm{Pt}∕\mathrm{Ni}\mathrm{O}∕\mathrm{Pt}$ capacitors with different resistance values. By reasoning out conductivity switching mechanisms from the switching characteristics and introducing multilayers consisting of NiO layers with different resistance values, we have reduced the reset current by two orders of magnitude.