INFRARED-ABSORPTION SPECTRA OF AMORPHOUS SILICON WITH GOLD

We determined the optical constants below the absorption edge of amorphous films of Si1-xAux (x between 0.07 and 0.30) prepared by getter sputtering in argon. In the range 0.15 to 0.5 eV we found that the absorption increased with increasing Au content and could be described by Mott's formula for a.c. conductivity σ(ω) ≈ ω2[In (I0/ω)]4 with I0 ≃ 4.5 eV at x = 0.11 and 3.8 eV at x = 0.29; in the range 10-100 K it changed only slightly with temperature. The absorption is interpreted as due to direct transitions involving Au atoms. © 1979.