Electronic Structure of Grain Boundaries and Interfaces in Polycrystalline Zinc Oxide

Abstract

Preliminary theoretical models for the electronic structure of grain boundaries and interfaces in polycrystalline ZnO have been constructed on the basis of self-consistent-field X-alpha scattered-wave (SCF-Xα-SW) cluster molecular-orbital calculations. The disposition and character of the interface states, relative to the valence and conduction bands of the otherwise perfect crystalline material, have been studied for clusters representing coordinatively unsaturated Zn surface sites and molecular O2 chemisorption thereon. The possible effects of the resuiting interface states on electron transport at grain boundaries in ZnO varistors have been addressed.