THEORETICAL INVESTIGATION OF THE ADSORPTION BEHAVIOR OF SI ADATOMS ONGAAS(001)-(2X4) SURFACES

We theoretically investigate the adsorption behavior of Si adatoms on GaAs(001)-(2 x 4) surfaces by ab initio calculations. The calculated r esults show that Si adatoms tend to be incorporated in the missing dim er trench when the Si coverage is small. Whereas favorable Si adsorpti on sites change from the missing dimer trench to the upper As dimers a s Si coverage increases. This coverage dependence of Si adsorption sit es is qualitatively consistent with recent experiments. Moreover, we c omment on the mechanism that governs the adsorption behavior of Si ada toms on GaAs surfaces.