Effects of double SiOx (x < 2) ultra-thin layers on bipolar resistive switching of ZnO-based nonvolatile memory

Abstract

We demonstrated the fabrication and application of a nonvolatile resistance-change memory with a structure of ZnO/SiOx/ZnO/SiOx/ZnO layers including double SiOx (x < 2) ultra-thin layers. The multiple layers were deposited using a radio-frequency magnetron-sputtering technique. Nonvolatile memory characteristics, such as an on/off resistance ratio, programming/erasing time, endurance cycles, data retention time, and switching power density were measured. Electrical measurements indicated that the double SiOx ultra-thin layers are important to achieve better resistive switching behaviors. The low-resistance state current conduction is controlled by a combination of ohmic conduction of conducting filaments in the ZnO layers and trap-assisted tunneling at weak points of the SiOx ultra-thin layers, while the high-resistance state current conduction is related to the more-stoichiometric insulating SiOx ultra-thin layers. The resistive switching mechanism is mainly attributed to the formation of effective conducting filaments through the weak points and phase change induced by a minimum O-ion movement at the weak points of the SiOx ultra-thin layer.