HREM study of ultra-thin, amorphous carbon films and structural changes of carbon forms to diamond under ion bombardment

High-resolution electron microscopy studies of ultra-thin, diamond-like amorphous carbon films are presented to investigate the initial stages of film growth and the formation of new carbon phases as well as their transformation to diamond under ion treatment. Films with a thickness of similar to 3 nm were deposited by r.f. magnetron sputtering at room temperature on a (001) Si clean surface. Specimens that were prepared for plan-view HREM observations only by chemical thinning revealed carbon crystallites, which are attributed to cubic carbon or to chaoite. The analysis shows that two cubic phases are present. Specimens of the same films prepared only by ion bombardment contain nuclei in which lattice fringes with a spacings equal to that of the (111) planes of diamond are resolved. (C) 1999 Elsevier Science S.A. All rights reserved.