Optical properties of amorphous metallic gold-silicon alloys

Abstract

The optical properties of amorphous films of ${\mathrm{Au}}_{1-x}{\mathrm{Si}}_x$ alloys were studied in the spectral region from 0.01-6.2 eV as a function of composition in the range $0.13\le x\le 0.50$. The reflectivity, dielectric function, and energy-loss spectra are presented. As discussed in a previous paper, the extremely short electron relaxation times give rise to some unusual features in $\epsilon \left(\omega \right)$. The onset of interband transitions shifts to higher energy as the silicon concentration is increased. The measured shifts are in surprisingly good agreement with those predicted by a simple rigid-band approximation.