Bipolar resistive switching behavior of La0.5Sr0.5CoO3−σ films for nonvolatile memory applications

Polycrystalline La0.5Sr0.5CoO3 (LSCO) film is prepared on Pt/Ti/SiO2/Si substrates by pulsed laser deposition in order to explore the resistive switching behavior of the Ag/LSCO/Pt structure. It is found that the oxygen stoichiometric LSCO (LSCO-2) structure does not possess distinct rectifying behavior, while the oxygen deficient La0.5Sr0.5CoO3−σ (LSCO-1) structure exhibits very stable bipolar resistive switching behavior, which is attributed to the oxygen vacancies in the LSCO film. The resistance ratio between high resistance state and low resistance state is about 100, which can be maintained up to 200 cycles and 25 h with no observable degradation, indicating that the Ag/LSCO-1/Pt device possesses very good endurance and retention characteristics. Moreover, the current-voltage characteristic of Ag/LSCO-1/Pt heterostructure can be well explained by the space-charge-limited conduction mechanism. The present results provide essential evidence for the analysis of the switching mechanism and evaluation of the memory devices.