Electron field-emission properties of Ag–SiO2 nanocomposite layers

Abstract

In this work, Ag–SiO2 nanocomposite layers were synthesized by introducing Ag nanoclusters into thermally oxidized SiO2 layers, using ion implantation. The field-emission (FE) properties of these layers were studied and correlated with the results from atomic force microscopy and transmission electron microscopy measurements. These nanocomposites exhibit good FE properties and give an emission current of 1nA at electric fields as low as 13V∕μm, for a dose of 5×1016Ag+∕cm2, compared with 204V∕μm for “bare” SiO2 layers. It is clearly demonstrated that the good FE properties of these nanocomposites are attributed to two types of local-field enhancement: one due to the surface morphology and the other due to electrical inhomogeneity. The isolated conductive Ag nanoclusters embedded in the electrically insulating SiO2 matrix provide a field enhancement due to the electrical inhomogeneity effect. Moreover, the implanted Ag ions diffuse to the surface, during the implantation process, and create dense surface-protrusion structure which provides a geometric local-field enhancement. The local-field-enhancement mechanisms in these samples are critically dependent on the implantation dose of Ag.