Impact of Germanium Wetting Nanolayers on the Optical Properties of Silver Films

Light absorption and optical percolation in nanosized silver films with a thickness of 5 and 10 nm are investigated experimentally. The influence of germanium underlayers with a mass thickness up to 1 nm with a step of 0.2 nm in the visible and near infrared wavelength range (300-2500 nm) on the above mentioned properties of silver films is studied. Optical percolation in silver films is associated with the peculiarities of growth mechanisms and modes of formation of metal condensate on an amorphous glass substrate. It has been shown that germanium underlayers predeposited on the glass substrate reduce the threshold thickness of the optical percolation transition in the silver film and increase their absorbency compared to similar films formed on a clean glass surface. The increase in the absorbency of the films deposited on the surface of the germanium sublayer is due to a decrease in the average linear size of the crystallites compared to similar samples formed on a clean glass surface, and thus an increase in the number of scattering metal centers per unit surface area.