Measurement of Thin Carbon Films Absorption in the Visible Spectrum

Abstract

The article is devoted to studying radiation absorption in the visible spectrum by thin carbon films. Two types of carbon films, diamond-like and graphite-like, with different structures, are investigated. The films are produced using laser vaporization of the initial material with a further coating of glass substrates. Measurements of light transmission through several samples of films with different thicknesses at three (or more) different areas are obtained for the wavelength range of 400-800 nm using the USB4000 compact fiber-optic spectrometer. The obtained results for the films with different thicknesses demonstrate scant differentiation of values (limiting to the same type of films). The imaginary parts of the films' complex refractive indices (absorption indices) are calculated. The comparison reveals the significant differences (by a factor of two or three) of the absolute values and trends of the absorption indices of diamondlike and graphite-like films. Both types of films are characterized by the expected increase in absorption when transitioning from the long-wavelength spectral region to the short-wavelength one. However, the rate of increase in absorption during such a transition is higher for the diamond-like films. These differences are related to the structure of the films.