Comparative study of adatom induced relaxations and energetics for Si, Ge and carbon adsorption on a (2x1) Si(001) surface

Surface complexes involving silicon, germanium and carbon adatom on predefi ned adsorption sites of the 2x1 reconstructed Si(001) surface are investiga ted for their energetics and associated structural relaxations, Tersoff's s emi-empirical potential is used and the relaxations are obtained by employi ng the Monte Carlo simulated annealing technique. The results for the cases of Si, Ge and carbon adsorptions are compared. It is found that Si and cc as adatoms on Si(001) 2x1 reconstructed surface behave in a similar fashion hut the carbon adatom behaves in a markedly different way. Specifically, t he carbon adatom induces a Si-C-Si chain configuration. It is also found th at the adsorption sites between two dimer rows are the most favourable ones .