Investigation on the chemical, structural and mechanical properties of carbon-germanium films deposited by dc-magnetron sputtering

Amorphous carbon-germanium films were deposited by dc-magnetron sputtering onto Si substrates leading to a set of films with Ge/C ratios ranging from 0 to 2. Nuclear techniques, Rutherford backscattering spectrometry and elastic recoil detection analysis, provided both the composition and the atomic density of the films, Raman results suggest that carbon and germanium atoms are segregated into distinct amorphous domains. X-ray diffraction analysis was also performed and the results confirmed the amorphous character of the films, already determined by Raman spectroscopy. The internal stress of the films was obtained by measuring the bending of the substrates and the hardness was measured by a nanoindentation technique. These mechanical properties were correlated to the Ge content of the films, an important reduction in both hardness and internal stress with the Ge incorporation was observed. (C) 1998 Elsevier Science S.A.