MOVPE strip-like self-organization of InAs grown on InP vicinal surfaces

We have investigated the influence of MOVPE growth parameters on the surface morphology of InAs nanostructures grown on 0.2 degrees misoriented (001)InP substrates. Thin layers of nominal thickness of about 3 and 6 ML were deposited at 500 degreesC with V/III flux ratios ranging from 50 to 240. The samples were cool down from 500 to 350 degreesC during 6 minutes under either arsine or phophine atmosphere. The influence of this step has been found to greatly determine the surface morphology of the nanostructures observed by atomic force microscopy. Dots self-aligned along the steps and forming a non continuous strip, regularly spaced every 3-4 terraces have been obtained. The morphology of the strips can be varied with the growth conditions (V/III flux ratio). In this work, we will propose a mechanism for the formation of the strips observed during the cooling under phosphine atmosphere taking into account an As --> P exchange.