Temperature Dependence of AC Conductivity in Lithium-Doped Zinc Oxide Films

Abstract

The mechanisms of charge carrier transport for alternating current in zinc oxide (ZnO) films with Li impurity, which creates acceptor and donor centers, are determined. A comparative study of the applicability of two models, quantum mechanical tunneling (QMT) and correlated barrier hopping (CBH), is carried out to interpret experimental data on alternating current electrical conductivity. Based on the analysis of the temperature dependence of conductivity at different frequencies, a choice was made in favor of the CBH model. The dependence of the thermal activation energy of conductivity on the concentration of the doping impurity Li in ZnO films is studied. It is established that the Meyer–Neldel rule, which relates the pre-exponential factor in the temperature dependence of alternating current conductivity to the activation energy, is fulfilled for compensated semiconductors in which donor and acceptor centers exist simultaneously.