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 Fe₃O₄ nanocrystals on Ge nuclei/Si with uniform and high resistive switching performance using low-temperature growth. The Fe₃O₄ nanocrystals on Ge nuclei had a well-controlled interface (Fe₃O₄/GeO_x/Ge) composed of high-crystallinity Fe₃O₄ and high-quality GeO_x 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 Fe₃O₄ and GeO_x 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.