Resistance Switching Memory Effect in Transition Metal Oxide Thin Films

The electric-pulse-induced resistance-change (EPIR) switching effect in oxides is attractive for its potential use in non-volatile resistance random access memories (RRAM). Such RRAM is highly valued due to its fast switching speed, nondestructive readout, and drastically reduced power consumption. The polarity-dependent, reversible resistance switching at room temperature has been observed in the two-terminal metal-oxide-metal thin film devices with transition metal oxide layers including perovskite oxides RE_1-xA_xMO₃ (RE-rare earth ions, A-alkaline ions, M-transition metal ions), and binary oxides MO_x (M-transition metal). These strongly correlated electron systems have been studied by scanning Kelvin probe microscopy, current AFM and confocal laser scanning microscopy, which indicate that the resistance switching occurs principally in the extended interface regions of the device (near the two electrical contacts). The basis for the EPIR effect is proposed as principally electric current-enhanced oxygen ion/vacancy migration in these interface regions.