Optical Parameters from Transmittance Spectrum (OPTIFIT)
Software developed by Rafael Alvarez and Alberto Palmero at the Materials Science Institute of Seville, Seville (SPAIN).
OPTIFIT analyzes the optical transmittance of thin films in the UV‐visible range and performs a parametric fit to a well‐known formula (see the Fitting Function section), allowing the calculation of the refractive index and the extinction coefficient of the film as a function of the wavelength. Outstanding features of the software include a graphical interface that allows wavelength range selection for the fit, and the incorporation of an automated procedure for the approximated estimation of the refractive index and thickness of the film.
The mathematical dependence between the transmittance spectrum and the optical parameters have been taken from Swanepoel [R Swanepoel, J. Phys. E: Sci. Instrum. 16 (1983) 1214]. The Sellmeier dispersion relation has been used for the refractive index [B. Tatian, Appl. Opt. 23 (1984) 4477], while the expression for the extinction coefficient includes an absorption band gap zone [N. Ghobadi, Int. Nano Lett. 3 (2013) 2] and a Taylor expansion on the frequency as a dispersion relation. The effect of the roughness has been included using the approach by Tikhonravov et. al [A.V. Tikhonravov, M.K. Trubetskov, A.A. Tikhonravov, A. Duparre, Appl. Opt. 42 (2003) 5140]. Finally, the estimation of the thickness and refractive index is taken from the review by Poelman and Smet [D. Poelman and P.F. Smet, J. Phys. D: Appl. Phys. 36 (2003) 1850].
OPTIFIT requires to have installed the freely distributable MATLAB Compiler Runtime (MCR). Once it is installed, open OPTIFIT.exe to start the program (first time OPTIFIT is executed, it may take a few seconds to start due to MCR initialization). Download MCR.
R. Alvarez, A. Garcia-Valenzuela, C. Lopez-Santos, F.J. Ferrer, V. Rico, E. Guillen, M. Alcon-Camas, R. Escobar-Galindo, A.R. Gonzalez-Elipe, A. Palmero, “High Rate Deposition of Stoichiometric Compounds by Reactive Magnetron Sputtering at Oblique Angles”, Plasma Process. Polym. 2016, 13, 960–964.