エポキシ樹脂複合絶縁系の光電流とTSC

電導に及ぼす界面の効果

抄録

In practical insulating systems epoxy resin is used mostly in the form of a composite with fillers. In order to use the epoxy-resin composite insulating systems at higher fields, it is important to investigate electronic properties at the epoxy-filler interface. We have prepared an epoxy-alumina two-layer composite film as a model system of a polymer-filler interface and studied the effect of interface on electronic conduction by measuring photocurrents and thermally stimulated currents (TSC).
At high fields and low temperature, holes are more mobile than electrons in epoxy-alumina composites. Most of the holes in the epoxy layer can pass through the epoxy-alumina interface and move in the alumina bulk, increasing the conduction current in the alumina by about two orders of magnitude. This interfacial phenomenon can not be explained by the conventional MaxwellWagner model. TSC measurements on the omposites showed that some of holes are trapped at the epoxy-alumina interface, in alumina bulk or the epoxy bulk near the interface, and give rise to new TSC peaks. At high fields and room temperature, the photoconduction is governed by the alumina layer and the dark conduction by the epoxy layer. These are well explained by the Maxwell-Wagner model. The electrical properties at the epoxy-filler interface are greatly affected by temperature and carrier species.