Surface alloying at InAs-GaAs interfaces grown on (001) surfaces by molecular beam epitaxy

In situ scanning tunnelling microscopy and reflection high energy electron diffraction have been used to study InAs-GaAs interfaces grown on (001) surfaces by molecular beam epitaxy. For the deposition of InAs on GaAs(001) a number of different surface reconstructions can be identified, depending on substrate temperature and InAs coverage, and there is significant evidence for alloying in the surface layer. An (In,Ga)As wetting layer is formed and the complete range of surface reconstructions are discussed, together with the tendency of indium atoms to segregate following the deposition of a further GaAs capping layer and the formation of GaAs-InAs-GaAs(001) interfaces. Finally, a comparison is made with the surface structure of GaAs layers deposited on InAs(001) substrates. (C) 1997 Elsevier Science B.V.