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COMPUTER SIMULATION OF DAMAGE IN DIAMOND DUE TO IONIMPACT AND ITS ANNEALING.
 

Summary: COMPUTER SIMULATION OF DAMAGE IN DIAMOND DUE TO ION­IMPACT
AND ITS ANNEALING.
David Saada 1;2 , Joan Adler 1 and R. Kalish 1;2
1 Department of Physics and 2 Solid State Institute, Technion­IIT, 32000, Haifa, Israel.
(September 28, 1998)
The structural modifications that a highly damaged region in diamond undergoes upon thermal
annealing are studied by molecular dynamic simulations, using the Tersoff potential. The validity
of this potential and of the computational methods applied here to properly describe the thermally
driven transition of diamond to graphite are verified by calculating the thermal graphitization of
a diamond slab and comparing the results with those of recently published (Alessandro De Vita
et. al., Nature 379, 523 (1996)) ab initio calculations. A deeply buried damage region in diamond
is obtained by imparting high momenta (corresponding to a kinetic energy of 416 eV) to up­to 12
lattice atoms aimed at the same point in the crystal. This leads to the practical amorphization of
a volume of a radius of 1.4 nm's. The annealing (3000K for up­to 25ps) of the damaged region,
obtained in this way, is studied by the MD calculations. It is found that dislodged carbon atoms in
the periphery of the damaged region tend to rearrange as threefold coordinated atoms in a planar
graphitic structure oriented along the !111? directions of the diamond. Threefold coordinate atoms
in the center of the damage region, where the damage density is high, tend to convert to a fourfold
coordinated configuration, i.e. regrow to diamond. This behavior is not found for a lightly damaged
diamond region, created by the energetic dislodgement of just one C atom. The findings of the

  

Source: Adler, Joan - Physics Department, Technion, Israel Institute of Technology

 

Collections: Physics