Spectroscopic ellipsometry extraction of optical constants for materials from oxide covered samples: Application to the plutonium/oxides system

Abstract

Spectroscopic ellipsometry is combined with scanning electron microscopy and multisample analysis of the measured oxide thickness difference from one sample at two different times during the oxide growth phase or from two separate samples to obtain the optical constants of the oxides. With the obtained thickness and optical constants of the oxides, the optical properties of the substrate material can be uniquely deduced. This methodology has been applied to obtain, the refractive indices and extinction coefficients of delta plutonium (δ-Pu) metal with 0.5 wt. % Ga in the wavelength region from 435 nm to 850 nm, without the influence of surface oxides. The presented methodology can also be applied to metals and semiconductors from surface oxidized samples, even when the oxides do not possess a common set of optical characteristics.