Effects of wetting layer structure on surface phase stability and on indium surface diffusion

We study the effects of surface reconstruction and step formation on the surface phase stability, of an InAs wetting layer on GaAs(001). In particular we focus our attention on the α2 and β2 (2 × 4) surface reconstructions. The two investigated reconstructions have been shown to be formed at an high In coverage, at the onset of the 2D→3D transition. The analysis of the connection between the step stability and the strain distribution around the step edges leads to the conclusion that the favoured step geometries are those minimising the strain. Finally, In diffusion on the flat reconstructed wetting layers has been investigated.We find: (i) the elements of the surface reconstructions favouring In diffusion; (ii) that In diffusion on these surfaces is strongly anisotropic, favoring the [-110] direction; (iii) that the As surface dimers introduce additional adsorption sites with high barriers for In escape.