Role of structural defects in the unipolar resistive switching characteristics of Pt∕NiO∕Pt structures

We investigated the resistive switching characteristics of two types of Pt∕NiO∕Pt structures with epitaxial and polycrystalline NiO layers. Both of these Pt∕NiO∕Pt structures exhibited unipolar resistive switching. Pt/epitaxial-NiO∕Pt showed unstable switching or no resistance state change after several repeated runs. Pt/polycrystalline-NiO∕Pt showed very reproducible switching. The experimental data indicated that microstructural defects (e.g., grain boundaries) played crucial roles in the reliability of the unipolar resistive switching behavior. This was further supported by first-principles calculations.