Abnormal volatile and normal stable bipolar resistive switching characteristics of hybrid nanocomposites: Morphology–defects–property ‘Relationship

Abstract

The characteristics of nano-fillers in a polymer matrix have a significant influence on the microstructural, thermo-mechanical, optical, and conductivity properties of organic-inorganic nanocomposites. In this study, we investigated the influence of inorganic component – ZnO nanoparticles (NPs) on the characteristics and properties of PVA-ZnO nanocomposites which have been applied as an insulation layer in a resistive switching (RS) device. Three nanocomposites originating from three different types of ZnO NPs exhibit different RS characteristics: Abnormal volatile RS is observed with the ∼20-nm-sized spherical-like NPs (Z1) and 15–20-nm-sized mixed shaped NPs (Z2), whereas normal nonvolatile bipolar RS is observed with the 50–150-nm-sized hexagonal rod-like NPs (Z3). The concentration and size of the intrinsic defects of the ZnO NPs as well as the thickness of the PVA-ZnO interface are responsible for the different charge transport paths, operating voltage ranges, and ON/OFF switching ratios of the memory devices. Simultaneously, the distinct sizes and morphologies of the ZnO NPs can affect the nanoholes among the PVA chains and induce various fractional free volumes in the nanocomposites. It may modify the conductivity of the nanocomposite layer or the resistance ratio of the memory devices. Understanding the influence of ZnO NPs size, morphology, and defects on the characteristics of RS of PVA-ZnO nanocomposites can help in the selection and management of functional applications, especially in the data storage field.