| Research Abstract |
In order to investigate the basic processes of the cluster implantation interaction of an ionized cluster beam with solids, we have developed the time-evolution Monte Carlo simulation codes DYACOCT.The DYACOCT code can be applied to the investigation of the cluster-impact phenomenon in a crystalline solid. In this program which is based on the binary collision approximation, trajectories of ions and recoil atoms are follwed dynamically. The effect of the multiple collisions of channeling particles is estimated precisely by the Molecular dynamic technique. In order to overcome the difficulties of the binary collision approximation of a low-energy projectile, many body encounter are also numerically solved by the molecular dynamics method, where a projectile collides at the same time with many atoms within its collision diameter. These codes can be successfully applied to the simulations of the radiation damage, the cluster-impact phenomena, the interaction of a highly charged particles
… More
with the solid surface and sputtering due to cluster impacts.
In order to specify the cluster effect of the cluster beam on the depth profile, It is necessary to know the depth profiles due to the ion implantation. For this purpose, the depth profiles of implanted ions has been calculated by the MARLOWE-like code, ACOCT code, where we used the (110) planar channeling and the <110> axial channeling of Si crystal. As an implantedion we used As^+ ion, because the clear-the-way effect of cluster ions is considered to be enhanced for the As-Si combination. For both 1.06 MeV As^+ on (100) Si surface and 20 keVAs^+ on (110) Si surface the calculated depth profile have two peaks, i.e., the random peak and the channeling peak. The former channeling peak is due to the planar channeling and the latter due to the axial channeling.
The cluster implantation was investigated by the DYACOCT code. The simulated depth profile due to 20 keV/atom (As)_n (n>10) bombarded normally on (110) Si surface has two interesting features : The random peak is shifted to the deeper layr than that of a single ion implantation. The second interesting feature is that the axial channeling peak is strongly deduced. Since M_<21>M_1 is less than unity for this combination, a lot of Si atoms have larger velocities than incident As atoms, and they clear the way for aftercoming cluster atoms, and they destroy the channel before cluster atoms come. Less
|
