Effect of Fe doping on the microstructure and electrical properties of transparent ZnOnanocrystalline films

Abstract

The transparent ZnO and Zn0.96Fe0.04O nanocrystalline films were deposited on the glass substrates by sol–gelmethod followed by repaid thermal annealing treatment. The grain size of the ZnO films was decreased bythe doping of Fe. X-ray diffraction measurements of the films showed the same wurtzite hexagonal structureand preferential orientation along the c-axis. Temperature dependence resistivity showed a semiconductortransport behavior for both compositions. At high temperature region, the transport mechanism can be fittedwith semiconductor behavior by Arrhenius equation, σ(T)=σ0 exp[−(Ea/kT)m] with m=1. The activationenergy Ea is increased from 0.47 meV for pure ZnO film to 0.69 meV for Zn0.96Fe0.04O film obtained fromequation. At low temperature region, the resistivity can be fitted well with the behavior of Mott variablerange hopping, σ(T)=σh0 exp[−(T0/T)n] with n=1/4. The results demonstrate that the crystallization andthe corresponding carrier transport behavior of the Zn1−xFexO films are affected by the doping of Fe in theZn1−xFexO films