Characterization of DLC : Si films by the gas effusion technique

In this work an investigation of hard DLC:Si films by the gas effusion tech nique is presented. Effusion of hydrogen, methane and higher hydrocarbons w as studied for films with silicon contents of up to 40 at%. Three major con tributions to the effusion spectra could be identified: (i) a desorption-li mited mechanism from the internal surfaces of a network of voids which coul d be observed even for large hydrocarbon molecules, indicating that low sil icon content material possesses a porous structure; (ii) a sharp peak relat ed to the abrupt graphitization of the films which dominates the spectra fo r hydrogen and methane effusion in the tow concentration range and is gradu ally shifted to high temperatures as the silicon content is increased; and (iii) a diffusion-limited mechanism that appears for high silicon content f ilms, suggesting that the films undergo a transition from porous to a relat ively compact structure. (C) 2000 Elsevier Science S.A. All rights reserved .