Determination of Thickness and Refractive Index of Antireflection Coating Thin Films from Reflectivity Spectrum Using Jaya Optimization Algorithm

Abstract

The number of parameters is often required to describe optical dispersion laws, and by using an appropriate global optimization procedure thickness and wavelength-dependent refractive index of anti-reflective coating thin films can be determined. In this work, we present a straightforward approach for determining the thickness and refractive index of a transparent anti-reflective coating thin film using photometric measurements of the reflectivity spectrum with the help of Jaya optimization algorithm. The algorithm fits experimentally measured reflectivity spectra with computationally obtained ones by using transfer matrix approach. The Sellmeier transparent dispersion relation is used to compute the wavelength-dependent refractive index. The algorithm is written in Python (version 3.9) with PyCharm as a programming software. To verify the performance of the self-developed program, it was applied on thin-film samples of MgF2, Al2O3, and SiO2 prepared by using the electron beam evaporation technique. The thicknesses and refractive index values generated using the Jaya algorithm for various transparent anti-reflective thin-film materials are compared to those obtained with standard spectroscopic ellipsometry measurements. The results obtained by the Jaya algorithm and those obtained by ellipsometry measurements are found to be in good agreement. Using our self-developed program based on the Jaya, it is shown that a simple reflectivity measurement may be beneficial for yielding essential information on the thickness and wavelength-dependent refractive index.