Low-Power, High-Performance, Non-volatile Inkjet-Printed HfO 2 -Based Resistive Random Access Memory: From Device to Nanoscale Characterization.

Low-power high-performance metal-insulator-metal (MIM) non-volatile resistive memories based on HfO high-k dielectric are fabricated using drop-on-demand inkjet printing technique as low-cost and eco-friendly method. The characteristics of resistive switching of Pt (bottom)/HfO/Ag (top) stacks on Si/SiO substrates are investigated in order to study the bottom electrode interaction with the HfO dielectric layer and the resulting effects on resistive switching. The devices show low Set and Reset voltages, high ON/OFF current ratio and relatively low switching current (~1 µA), which are comparable to the characteristics of current commercial CMOS memories. In order to understand the resistive switching mechanism, direct structural observation is carried out by field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HRTEM) on cross-sectioned samples prepared by focused ion beam (FIB). Electron energy loss spectroscopy (EELS) inspections discard a silver electro migration effect, evidencing that the resistive switching mechanism is due to the formation of an oxygen vacancy-based conductive filament through the HfO layer.