Local transport properties, morphology and microstructure of ZnO decoratedSiO2 nanoparticles

Abstract

We report on a novel, surfactant free method for achieving nanocrystalline ZnO decoration of anSiO2 nanoparticle at ambient temperature. The size distributions of the naked and decoratedSiO2 nanoparticles are measured by means of dynamic light scattering, and a monodispersedistribution is observed for each. The morphology and microstructure of the nanoparticlesare explored using atomic force microscopy and high resolution transmissionelectron microscopy. Investigation of the optical properties of the ZnO decoratedSiO2 nanoparticles shows absorption at 350 nm. This blue shift in absorption as compared tobulk ZnO is shown to be consistent with quantum confinement effects due to the small sizeof the ZnO nanocrystals. Finally, the local electronic transport properties of thenanoparticles are explored by scanning conductance atomic force microscopy. Amemristive hysteresis in the transport properties of the individual ZnO decoratedSiO2 nanoparticles is observed. Optical absorption measurements suggest thepresence of oxygen vacancies, whose migration and annihilation appearto contribute to the dynamic conduction properties of the ZnO decoratednanoparticles. We believe this to be the first demonstration of a ZnO decoratedSiO2 nanoparticle, and this represents a simple yet powerful way of achieving theoptical and electrical properties of ZnO in combination with the simplicity ofSiO2 synthesis.