Modification of magnetron sputtered a-Si 1- xC x:H films by implantation of Ge +

Implantation of Ge ⁺ ions into a-Si _{1- x}C _x:H films deposited by RF reactive magnetron sputtering of silicon and graphite, was carried out in order to obtain optical contrast in the layers. The expected optical effect which is a transmission edge shift to the lower photon energies accompanied by a decrease of the transmission coefficient was observed. This effect is more pronounced with higher implantation doses. Ion implantation of Ge ⁺ considerably increases the absorption coefficient (α) even for the lowest dose which is of the order of 10 ¹⁵ cm ^-2. This increase is most pronounced in a narrow energy region around 2.2 eV (1.8-2.4 eV). Raman, infrared (IR) and photoelectron spectroscopy (XPS) measurements were used to study the structure and bond configurations of the implanted films. These measurements reveal that ion implantation introduces an additional disorder in the films as well as leads to a chemical modification of the films, which could be related to the changes of the optical properties.