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O: Oberflächenphysik

O 32: Epitaxie und Wachstum (II)

O 32.13: Vortrag

Donnerstag, 29. März 2001, 18:30–18:45, C

Alloying and adatom diffusivity in the initial stages of InAs/GaAs heteroepitaxy — •Evgeni Penev, Peter Kratzer, and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4–6, 14195 Berlin-Dahlem

Heteroepitaxy of InAs on GaAs is an important process for the growth of semiconductor nanostructures. In the initial stages of molecular beam epitaxy of thin InAs films, substantial cation intermixing was observed which converts the growing surface into a GaInAs alloy, accompanied by the appearance of surface reconstructions with × 3 periodicity along the [110] direction.

We have carried out density-functional theory calculations to address the thermodynamic stability of × 3-reconstructed mono- and bilayers of In_xGa_1−xAs on a GaAs(001) substrate. The surface energies are compared with the stable c(4× 4) and β 2(2× 4) reconstructions of the GaAs(001) surface, and with β 2(2× 4) reconstructed monolayers of InAs on GaAs(001). The diffusivity of an In adatom on a × 3-reconstructed wetting layer is discussed for a particular composition x=1/3 that is realized for the InGaAs(001)-(2× 3) surface alloy.