Improved bipolar resistive switching properties in CeO2/ZnO stacked heterostructures

This paper reports the resistive switching effects of ZnO, CeO2 and CeO2/ZnO stacked heterostructure deposited on Nb:SrTiO3 substrates by pulsed laser deposition. The CeO2/ZnO stacked heterostructure shows high resistive switching ratio of over 104 at a read voltage of −0.5 V and an expected retention ability of ten years, which is better than that of ZnO- or CeO2-based device. Furthermore, multilevel resistance states could be adjusted by changing the maximum value of the applied voltage, which shows promise for high-performance nonvolatile multilevel memory application. Studies indicated that the trap-mediated space charge limited conduction governs the low- and high-resistance states. The good resistive switching characteristics of CeO2/ZnO stacked heterostructure could be attributed to the carrier injection-trapped/detrapped process at the CeO2/ZnO interface and ZnO films in which oxygen vacancies act as ‘trapping center’.