Surface and in-depth distribution of sp2 and sp3 coordinated carbon atoms in diamond-like carbon films modified by argon ion beam bombardment during growth


Diamond-like carbon (DLC) film surfaces were prepared by laser ablation of a graphite target and, with the simultaneous ion argon bombardment of the growing layer. In-depth distribution of coordinated carbon atoms has been determined non-destructively and quantitatively from angular-resolved C 1s spectra aided by maximum entropy method. The results have shown the surface enrichment by the sp2 coordination, while under the surface, the sp3 coordination prevails. The depth distribution was independently confirmed by Auger spectra C KVV analysis and by the measurement of layer mass density.

The reconstructed depth profiles of the carbon atom bonding states of the DLC sample grown under 40 eV Ar ion beam energy with error bars to judge the reliability of the profiles.