Molecular dynamics modeling of microstructure evolution during growth of amorphous carbon films

Classical molecular dynamics simulations, using Brenner's bond-order interatomic potential model, is used to study the bonding microstructure formation during quench from liquid and during growth on a diamond surface. For a 64-atom quench simulation we find 56 sp3- and 8 sp2-bonded carbon atoms, in qualitative agreement with tight-binding simulations. The growth of amorphous carbon films was simulated by depositing carbon and hydrogen atoms onto a diamond surface at energies up to 100 eV. The simulated films are amorphous with a maximal density near the deposition energies (20-40 eV) used to grow films on magnetic disks. Lower deposition energies yield open graphitic structures, while much higher deposition energies cause the surface to ablate, leading to a poorly defined interface. The hardness calculated from the densest simulated films is about twice that found experimentally. © 1996 ESCOM Science Publishers B.V.