Figure 5.

Optical properties and figures-of-merit for Al films deposited at room temperature at a base pressure of 3 × 10^–8 Torr. Solid and dotted lines compare properties for a template-stripped film deposited at a fast rate (150 Å/s) and the as-deposited surface from a film grown at a rate more typically found in the plasmonics literature (5 Å/s), respectively. Despite the additional roughness in the latter case, the measured dielectric functions are dominated by the presence of aluminum oxide in the film. Note how the fast rates are consistent with Rakić²⁴ (dashed lines). (a) and (b) show the real and imaginary parts of the dielectric function, respectively. (c) and (d) plot calculated quality factors²⁶ for the localized surface plasmon resonance in spherical structures (Q_LSPR) and surface plasmon polaritons (Q_SPP), respectively.