Nucleation in a-C:H
amorphous carbon with 50 hydrogen atoms at 3.5 g/cc.
Kohary at al. (Diamond and Related materials, 11(2002), 513)
Molecular Dynamics simulation of the bombardment process
during bias enhanced nucleation phase of Chemical Vapor
Energy of ions was 20 and 40 eV.
The total sp3 content in the film increased.
Hydrogen in semi-frozen diamond: free-to move C atoms
sandviched between two layers of frozen diamond:
Hydrogen initially placed at the Td site of the frozen diamond
diffused quickly to a stable location on the boundary between
the frozen and unfrozen region.
Hydrogen initially placed at the Td site of the unfrozen region
diffused to an ET site of in the unfrozen region.
first layer - frozen diamod, second layer - unfrozen diamond,
third layer - vacuum.
Hydrogen initially placed at the Td site diffused to the surface
forming a C atom vacancy, second H diffused to the vacancy,
third H atom diffused out of the diamond lattice.
Hydrogen diamond/a-C composite: The frozen diamond core
inside the amorphous carbon network at 3.5 g/cc.
Hydrogen were implanted to the same site one after another.
When local saturation achieved, The H site was changed and
the sequence restarted.
For each simulation H duffuses out from the diamond core to
the region which was low in sp3 bonds.
As the number of H atoms increased, numbers of sp3
and numbers of sp2 bonds decreased till saturation
of the H achieved and
a decrease of sp3 bonds begins. Then the H interstitial site is
replaced and the situation repeats itself. The sp3
bonds form near
previously formed sp3 bonds, which can suggests growth of the
diamond cluster. Up to 26 hydrogen atoms (12 %) were implanted.
- More results of Oren are
Lifshitz at al (Science, 297(2002), 1531)
Diamond-like sp3 cluster could spontaneosly form in
a-C:H matrix with a density of 3 g/cc and 25% of H atoms.
- My ab initio simulations of hydrogen in diamond are