Conduction mechanism of non-Ohmic zinc oxide ceramics

Abstract

The conduction mechanism of non‐Ohmic ZnO ceramics is investigated. In order to explain the non‐Ohmic property, a new energy‐band model composed of a thin intergranular layer with traps sandwiched between Schottky barriers formed opposite each other is proposed. According to the newly proposed energy‐band model, the non‐Ohmic property of ZnO ceramics is mainly governed by field emission for the reverse‐biased Schottky barrier in the voltage region above the threshold voltage in the V‐I curve and by thermionic emission in the voltage region below the threshold voltage. The energy‐band model and the conduction mechanism discussed in this paper are appropriate for the explanation of experimental results, not only those presented in previous papers, such as the effect of additives, the V‐I curve and its temperature dependence, but, additionally, the dielectric properties, the asymmetrical degradation of the V‐I curve, and the thermally stimulated current.