Investigation of the switching mechanism in TiO2-based RRAM: a two-dimensional EDX approach

The next generation of non-volatile memory storage may well be based on resistive switching in metal oxides. TiO2 as transition metal oxide has been widely used as active layer for the fabrication of a variety of multi-state memory nanostructure devices. However, progress in their technological development has been inhibited by the lack of a thorough understanding of the underlying switching mechanisms. Here, we employed high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) combined with two-dimensional energy dispersive X-ray spectroscopy (2D EDX) to provide a novel, nanoscale view of the mechanisms involved. Our results suggest that the switching mechanism involves redistribution of both Ti and O ions within the active layer combined with an overall loss of oxygen that effectively render conductive filaments. Our study shows evidence of titanium movement in a 10 nm TiO2 thin-film through direct EDX mapping that provides a viable starting point for the improvement of the robustness and life time of TiO2-based resistive random access memory (RRAM).