Effect of energy on direct ion beam deposition of carbon thin films: induced defects and graphitization

The direct deposition of ions at low energy enables fine control of the fun damental processes of thin film formation. Using a source of carbon and nic kel ions with energy ranging from a few tens to a few hundreds of electron volts, combined with an ultra-high vacuum scanning electron tunneling micro scope, we have studied the formation of thin films for thicknesses equivale nt to less than one atomic layer. We have revealed the influence of ion-ind uced defects on the formation mechanisms of the thin film as a function of ion energy using the dynamic scaling analysis of the roughness of the thin film terminal surfaces. In the case of carbon ions we acknowledge the forma tion of an sp(2) bonded layer at 300 degrees C, that is above the critical temperature where the formation of a diamond-like carbon sp(3) layer recess as described by the subimplantation model [4]. (C) 2000 Elsevier Science S .A. All rights reserved.