The Conductive Property of ZnO QDs-SiO2 and ZnO QDs-SiOxNy Nanocomposite Films

The dc and ac conductive properties of ZnO QDs-SiO2 and ZnO QDs-SiOxNy nancomposite films prepared by the target-attached sputtering method are investigated. Both two nanocomposite samples reveal a typical characteristic of a metal-oxide varistor (MOV) on the J-E plots with distinct threshold electric fields (E-th) which are affected by the molecular bonding configurations in the matrix and at the dot/matrix interfaces. The two systems exhibit dissimilar dependences of dc conductivity (sigma(dc)) on the ZnO content, revealing the limitation of conventional percolation models in which the surface interaction term is usually ignored. The ac conduction behaviors of the two nanocomposite systems were also analyzed and their percolation concentrations V-c (22.75% for ZnO QDS-SiO2 and 20.78% for ZnO QDs-SiOxNy) are determined by the construction of master curves. Analytical results illustrated that the dielectric matrix type indeed affects the defect configuration and transport behaviors inside ZnO dots. Hence, manipulation of dielectric matrix type can possibly achieve various optical and electrical properties in ZnO QDs-dielectric nanocomposite systems.