Optical properties of a nanostructured glass-based film using spectroscopic ellipsometry

Abstract

Nanostructured glass films, which are fabricated using spinodally phase-separated low-alkali glasses, have several interesting and useful characteristics, including being robust, non-wetting and antireflective. Spectroscopic ellipsometry measurements have been performed on one such film and its optical properties were analyzed using a 5-layer structural model of the near-surface region. Since the glass and the film are transparent over the spectral region of the measurement, the Sellmeier model is used to parameterize the dispersion in the refractive index. To simulate the variation of the optical properties of the film over the spot size of the ellipsometer (~3 × 5 mm), the Sellmeier amplitude is convoluted using a Gaussian distribution. The transition layers between the ambient and the film and between the film and the substrate are modeled as graded layers, where the refractive index varies as a function of depth. These layers are modeled using a two-component Bruggeman effective medium approximation where the two components are the layer above and the layer below. The fraction is continuous through the transition layer and is modelled using the incomplete beta function.

Generalized Ellipsometry Measurements of Crystalline Thin Film and Bulk Tin Oxide

“…If the interface layer is graded where the dielectric function varies as a function of the interface layer thickness, then the fraction becomes a function of the position within the interface layer. One way of parameterizing this fraction uses the incomplete Beta function [ 22 ] and then break the interface layer into m + 1 sublayers each with a different dielectric function. If the interface layer is divided into m layers with thickness d i , then the total interface thickness is expressed as …”

Optical Characterization of Inhomogeneous Thin Films Deposited onto Non-Absorbing Substrates

“…The overlayers exhibiting inhomogeneity were characterized, for example, in [39,40]. The optical characterization of the transition layers was realized, for instance, in [41][42][43][44][45][46]. The spectral dependencies of the optical constants and thickness values of these transition layers are determined within this characterization.…”

“…Simultaneously, the complete optical characterization of the films occurring above the transition layers is performed too (see, e.g., [43]). It should be noted that the optical characterization of the thin films and their overlayers or transition layers presented in the literature was carried out using the optical quantities corresponding to reflected light (see, e.g., [38][39][40][41][42][43][44][45][46]).…”