Surface phases of GaAs and InAs (001) found in the metalorganic vapor-phase epitaxy environment

We have characterized the (2x4) and (4x2) reconstructions of GaAs and InAs (001) that are present in a metalorganic vapor-phase epitaxy (MOVPE) reacto r. Scanning tunneling micrographs show that these surfaces are terminated w ith arsenic and gallium (or indium) dimers. The (2x4) dimer row exhibits a mottled appearance, which is ascribed to the adsorption of alkyl groups on some of the sites. On the (4x2), <10% of the surface is covered with small (2x4) islands. These results show that, in the MOVPE environment, the GaAs and InAs surface structures are nearly the same as those found in ultrahigh vacuum molecular beam epitaxy. (C) 1998 American Institute of Physics. [S0 003-6951(98)02235-9].