Ellipsometric Characterization of the Optical Constants of Metals: Thin Film versus Nanoparticle

Abstract

The characterization of the optical constants of metals is extensive and dates back many decades.1 Particular emphasis has been placed on gold, with calculations of the dielectric function performed using both photometric 2,3 (reflection and transmission) and ellipsometric 4–8 measurements. Depending on the type of sample being measured (thin film or bulk), the deposition method used, and the post-deposition annealing, slightly different optical constants have been determined. The dependence of the optical constants on the details of the sample preparation arises from variations in the microstructural characteristics of the samples. Different grain morphologies will affect the surface roughness, void content, strain-induced lattice deformation, and electron scattering, all of which will affect the calculations of the dielectric function of the metal, εm.9