Single adatom site exchange during the Ge growth on group V element covered Si(0 0 1)

The site exchange between Ge and surfactant atoms in the growth of Ge on the group V element-covered Si(0 0 1) has been studied using first-principles total energy calculations. On the Bi-covered Si(0 0 1) and the As-covered Si(0 0 1), a single adatom site exchange process can occur energetically, but with different pathways. The energy barriers for the single adatom site exchange are very small. The site exchange can therefore occur very easily. This will suppress the Ge diffusion, and favors the layer-by-layer growth mode.