Surface diffusion of Si,Ge and C adatoms on Si （001） substrate studied the molecular dynamics simulation

Depositions of Si, Ge and C atoms onto a preliminary Si (001) substrate at different temperatures are investigated by using the molecular dynamics method. The mechanism of atomic self-assembling occurring locally on the flat terraces between steps is suggested. Diffusion and arrangement patterns of adatoms at different temperatures are observed. At 900 K, the deposited atoms are more likely to form dimers in the perpendicular [110] direction due to the more favourable movement along the perpendicular [110] direction. C adatoms are more likely to break or reconstruct the dimers on the substrate surface and have larger diffusion distances than Ge and Si adatoms. Exchange between C adatoms and substrate atoms are obvious and the epitaxial thickness is small. Total potential energies of adatoms and substrate atoms involved in the simulation cell are computed. When a newly arrived adatom reaches the stable position, the potential energy of the system will decrease and the curves turns into a ladder-like shape. It is found that C adatoms can lead to more reduction of the system energy and the potential energy of the system will increase as temperature increases.

Surface diffusion of Si, Ge and C adatoms on Si (001) substrate studied by the molecular dynamics simulation

Depositions of Si, Ge and C atoms onto a preliminary Si (001)substrate at different temperatures are investigated by using themolecular dynamics method. The mechanism of atomic self-assemblingoccurring locally on the flat terraces between steps is suggested.Diffusion and arrangement patterns of adatoms at differenttemperatures are observed. At 900~K, the deposited atoms are morelikely to form dimers in the perpendicular [110] direction due tothe more favourable movement along the perpendicular [110]direction. C adatoms are more likely to break or reconstruct thedimers on the substrate surface and have larger diffusion distancesthan Ge and Si adatoms. Exchange between C adatoms and substrateatoms are obvious and the epitaxial thickness is small. Totalpotential energies of adatoms and substrate atoms involved in thesimulation cell are computed. When a newly arrived adatom reachesthe stable position, the potential energy of the system willdecrease and the curves turns into a ladder-like shape. It is foundthat C adatoms can lead to more reduction of the system energy andthe potential energy of the system will increase as temperatureincreases.