The Optical Constants of Highly Absorbing Films Using the Spectral Reflectance Measured By Double Beam Spectrophotometer

Abstract

The optical constants of the metal thin films of Rhodium have been determined, the phase angles was determined using the measured spectral reflectance R(l) by Kramers-Kronig relations. Then, the real part of the refractive index is calculated by the approach of Heavens when the film is highly absorbing, in that range the real refractive was found to be in order of the extinction coefficient k.

The interference reflectance spectra at normal incidence for different thicknesses of amorphous metal films deposited by thermal evaporation have been obtained in the spectral range 400~800 nm. We propose a method for determination of the refractive index and extinction coefficients of highly absorbing films. This method is based on measurements of reflectance of the film at normal incidence alone, simulations of the theoretical accuracy and the effect of the error of the spectral reflectance measurements in the determination of the optical constants of the film are analyzed.

Keywords: optical constants, refractive index , thin film , reflectance and absorption coefficient .