Figure 1
From: Extreme tunability in aluminum doped Zinc Oxide plasmonic materials for near-infrared applications

Room temperature permittivity and carrier concentrations.
Wavelength dependence of the (a) real and (b) imaginary permittivity of Al:ZnO (1:20 ratio) films containing low (69 nm) to higher (577 nm) thickness. (c) Thickness dependence of crossover wavelength, λc and calculated carrier concentration using the Drude-Lorentz model. (d) Dependence of measured carrier concentration (ne) and sheet carrier density (ns) of AZO films.