Abstract:
Mesoporous gold thin films on glass substrates were fabricated by sputtering
of AuAl2 precursor films followed by a de-alloying etch. The resulting
sponge-like Au films have very high internal surface area due to nanoscale
pores and channels. Scattering is not significant and the optical properties
for such nanostructured films were examined using ellipsometry and
spectrophotometry. The complex refractive indices of the optically
equivalent uniform smooth layer satisfy Kramers–Kronig (KK)
self-consistency but have unusual dispersion relations and magnitudes for a
film containing the amount of noble metal present. The reflectance at
infrared wavelengths is neither metal- nor insulator-like, and the indices
have unique dispersion curves.
