Silicon Oxide Reram Device

Abstract

We demonstrate a silicon oxide redox-based resistive RAM (ReRAM) device. The resistance switching in our devices is intrinsic to changes within the oxide layer and thus it is not an effect of diffusion of metallic ions from the metallic electrode as in the case of electrochemical metallization (ECM) cells. In addition to standard two-level switching we demonstrate a multi-level switching as well as an analogue modulation of resistance. It is possible to switch devices in both bipolar and unipolar switching modes while dynamically adjusting the device electronic properties, in particular two desirable properties: non-linearity in I-V curves and self-rectification. We demonstrate room temperature quantisation of conductance in our devices, implying ballistic transport of electrons through a quantum constriction, associated with an individual conductive filament in the oxide bulk. Scanning tunnelling microscopy (STM), atomic force microscopy (AFM), and conductive atomic force microscopy (C-AFM) measurements provide a more detailed insight into both the location and the dimensions of the conductive filaments responsible for the resistance change. Further, we demonstrate the field-driven movement of oxygen ions that causes large-scale changes in oxide layer that are accompanied with the oxygen release. We report on the material changes leading to resistance switching using secondary ion mass spectroscopy (SIMS), x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Finally we demonstrate and discuss on the feasibility of using the ReRAM cell to model aspects of the electrical activity of the neuron that could provide a novel way of using ReRAM devices in neuromorphic systems.