Correlated barrier hopping in NiO films

The ac conduction in NiO films has been investigated in the frequency range 10 Hz${10}^{9}$ Hz and at temperatures between 10 and 300 K. The frequency and the temperature dependence of the electrical conductivity can be consistently explained within a model developed for the mechanism of charge transfer in amorphous semiconductors which proposes that charge carriers hop over potential barriers between defect sites, the height of the barriers being correlated with the intersite separation.