Selective area growth of InAs nanostructures on faceted GaAs microstructures by migration enhanced epitaxy is studied. By an optimization of the growth conditions and a study of the facet development, well-defined GaAs microstructures with facets mostly belonging to the crystal plane families {01n}, {11n} and (001) are fabricated. Subsequently deposited InAs shows a preferred nucleation on (001) top facets as well as on {012}/{013} and {011} facet boundaries. By the understanding of the InAs nucleation mechanism, precisely positioned In(Ga)As/GaAs nanostructures such as quantum dots and quantum dot chains are achieved. To investigate the interface properties, transmission electron microscopy and energy-dispersive x-ray spectroscopy measurements are performed. The measurements reveal a relatively high incorporation of Ga into the InAs nanostructures even for InAs deposited at a low growth temperature of 470 degrees C. (c) 2013 Elsevier B.V. All rights reserved.