Direct determination of barrier voltage in ZnO varistors

Abstract

Single barriers in a ZnO varistor are measured separately. The step voltage at a grain boundary is 3.6 V at 1 μA. No great differences could be found between samples obtained from several suppliers. In a SEM the barriers could be detected by the voltage‐contrast method. By using electron‐beam‐induced currents the spots where current is flowing may be located.