Hard graphitic-like amorphous carbon films with high stress and local microscopic density

In this work, we report unusual properties of amorphous carbon films prepar ed by ion beam-assisted deposition using different noble gases (neon, argon , and krypton). Independent of the noble gas ions used, the intrinsic compr essive stress and plasmon energy increase sharply with the assisting ion be am energies up to 100 eV. Above this energy, the material properties depend on the mass of the ion. The highest values of stress (similar to 12 Cpa) a nd plasmon energy associated with the C1s core electron (29.5 eV) are of th e same order of magnitude as those reported for highly tetrahedral amorphou s carbon films. Structural results, however, indicate that the material is composed of a hard, highly stressed, and locally dense graphite-like networ k, i.e., a predominantly sp(2)-bonded material. It is suggested that, the i on bombardment compacts the film structure by reducing the interplanar clus ter distances, generating high compressive stress and high local density. T he differences in the properties of the films introduced by Ne, Ar, and Kr bombarding ions are also discussed. (C) 2001 American Vacuum Society.