Figure 4.

Real (a) and imaginary (b) part of the dielectric function of AZO films of different doping levels (2 and 4 at. %) as extracted by ellipsometry measurements. Measurements on a ZnO film (orange lines) are reported for reference. The dashed lines in ε₁ indicate the plasma frequency for 2 at. % AZO (green) and 4 at. % AZO (blue line). (c) Squared optical absorption coefficient versus photon energy for AZO films of different doping levels (2 and 4 at. %) as well as a ZnO film. The inset table shows the band gap values determined by a linear extrapolation along the absorption edge to the background.