Features of Carbon and Silicon Thin Films Reflection Spectra in the Visible Region

Abstract

The article is devoted to the reflection of visible light from a thin absorbing film. For a number of reasons, thin films have recently been the subject of close study. As part of the work, several non-metal films were fabricated on a glass substrate: silicon films (by resistive evaporation) and carbon films (using laser evaporation). The resulting films have an optical thickness in the range of 1 μm (that is, the actual layer thickness is in the range of 0.2-0.4 μm) and at the same time noticeably absorb the light flux. The films were processed according to the standard method in the visible region using a USB4000 spectrometer. Reflection spectra for each of the films were plotted for several different points on the surface. The spectra look similar when differences in numerical values are not considered. The contribution of the interference of rays reflected from the front and rear boundaries is significant at long wavelengths (in the red region), whereas the interference practically disappears against the background of instrument noise in the short wavelength region (violet part of the spectrum). The reason for this is that absorption during propagation of the short-wavelength part inside the film significantly reduces the intensity of the beam reflected from the rear surface of the film.