Role of Te on the morphology of InAs self-assembled islands

The effect of Te presence on the morphology and distribution of InAs islands grown by molecular beam epitaxy on GaAs is investigated. Atomic force microscopy was used to follow the dependence of height, radius, and surface density on Te and InAs coverages. They ranged from zero to 0.45 monolayers (ML) of Te, and from 1.8 to 3.5 ML for InAs. We obtained a higher density of islands for samples covered with 0.3 ML of Te. The number of islands is essentially the same for samples covered with 0 and 0.45 hit of Te. A delay on the onset of island growth is observed for samples with theta(Te) = 0.45 ML. The surface morphology is also different for samples with Te when compared with the Te free sample. We suggest that for theta(Te) = 0.45 ML the coherence-incoherence transition is either delayed or absent for the InAs coverage range studied. (C) 1998 American Vacuum Society.