LATERAL AND VERTICAL ORDERING IN MULTILAYERED SELF-ORGANIZED INGAAS QUANTUM DOTS STUDIED BY HIGH-RESOLUTION X-RAY-DIFFRACTION

We have studied multiple layers of self-organized InGaAs-islands grown on GaAs by x-ray diffraction reciprocal space mapping. We found an an isotropy of the dot spacing in [100] and [110] direction consistent wi th an ordering of the dots in a two-dimensional square lattice with ma in axes along the [100] direction and a lattice parameter of 55 nm. Th e nearly perfect vertical alignment (stacking) of the dots was deduced from the diffraction peak shape. (C) 1997 American Institute of Physi cs.