Resistive switching memory performance in oxide hetero-nanocrystals with well-controlled interfaces.

For realization of new informative systems, the memristor working like synapse has drawn much attention. We developed isolated high-density FeO nanocrystals on Ge nuclei/Si with uniform and high resistive switching performance using low-temperature growth. The FeO nanocrystals on Ge nuclei had a well-controlled interface (FeO/GeO/Ge) composed of high-crystallinity FeO and high-quality GeO layers. The nanocrystals showed uniform resistive switching characteristics (high switching probability of 90%) and relatively high Off/On resistance ratio (58). The high-quality interface enables electric field application to FeO and GeO near the interface, which leads to effective positively charged oxygen vacancy movement, resulting in high-performance resistive switching. Furthermore, we successfully observed memory effect in nanocrystals with well-controlled interface. The experimental confirmation of the memory effect existence even in ultrasmall nanocrystals is significant for realizing non-volatile nanocrystal memory leading to neuromorphic devices.