Atomic Structures of a Monolayer of AlAs, GaAs, and InAs on Si(111)

Abstract

We study atomic structures of a monolayer of AlAs, GaAs, and In As on a Si(111) substrate from first-principles. The surface with the stacking sequence of ...SiSiMAsSiAs is energetically more stable than the surface with the stacking sequence of ...SiSiSiAsMAs, where M is Al, Ga., or In. The atomic structure of the three top layers of the low-energy surfaces are quite robust, irrespective of and the atomic structure of the AlAsSiAs terminated surface and that of the GaAsSiAs terminated surface are very similar. For the high-energy AsMAs terminated surfaces, the broken local tetrahedral symmetry plays an important role in the atomic structures. The calculated atomic structures of In As on the Si(111) substrate depart most from the structure of crystalline Si.