Electronic structure of conducting Al-doped ZnO films as a function of Al doping concentration

Transparent conducting Al-doped ZnO films were deposited by atomic layer deposition with various of Al doping concentrations. In order to explain the change in resistivity of Al-doped ZnO films depending on Al doping concentration, we investigated the correlations between the conducting property and electronic structure in terms of atomic configuration, the evolution of the conduction band and band gap, and band alignments (conduction band offset between minimum of conduction band and Fermi level, ΔE_Cb). ZnO film Al-doped at ∼ 3 at% and deposited at 250 °C showed the lowest resistivity, which resulted in changes in the conduction band of insulating Al₂O₃ film, and increases in the band gap and conduction band offset (ΔE_Cb).