Influence of Te on the morphology of InAs self-assembled nanocrystals

InAs nanocrystals were grown by MBE on GaAs(1 0 0) with Te coverage (0(Te)) ranging from zero to 0.45 monolayers (ML). The height, radius and surface density of these nanocrystals (nominal InAs coverage varying from 1.8 to 4. 5 ML) were measured by atomic force microscopy (AFM). We observed that for 0(Te) = 0.45 ML the transition coherence-incoherence is either delayed or a bsent for the InAs coverage range studied. Te deposition has the opposite e ffect of the pressure of As. regarding the size the islands. The size of th e nanocrystals, for 0.45 monolayers of Te, varies smoothly up to 3.5 monola yers of InAs. Samples with Te resulted in 'soft' small nanocrystals. which could be a sign of a lack of stoichiometry in the small nanocrystals. (C) 1 999 Elsevier Science B.V. All rights reserved.