Resistive switching behaviors of cobalt oxide films with structural change by post-thermal annealing

Abstract

We have studied the resistive switching behaviors of cobalt oxide films with structural changes by a post-thermal annealing process. During post-annealing at temperatures of 500-700 degrees C for the CoOx films deposited by ultrahigh-vacuum RF magnetron sputtering, two structural phases of CoO and Co3O4 were modulated by selection of ambient N-2 or O-2 gases. As a device application of these films, the resistive random-access memory (ReRAM) structures of p(+)-Si/CoOx/Ti/Au were fabricated with CoO or Co3O4 films by post-annealing at 700 degrees C under N-2 and O-2 atmosphere, respectively. The resistive switching characteristics of the CoO device appeared much better than that of the Co3O4 device, also showing good uniformity from a cumulative probability distribution, long non-volatile retention characteristics of 10(4) s, good endurance of similar to 100 cycles, and an excellent current ratio of 10(4). These results demonstrate the method to provide stable and good resistive switching properties of sputtered CoO films using the phase selection during post-thermal annealing.