Structure of droplet-epitaxy-grown InAs/GaAs quantum dots

We have used a direct x-ray phasing method, coherent Bragg rod analysis, to obtain sub-angstrom resolution electron density maps of the InAs/GaAs dot system. The dots were grown by the droplet heteroepitaxy (DHE) technique and their structural and compositional properties are compared with those of dots grown by the strain-driven Stranski-Krastanov method. Our results show that the Ga diffusion into the DHE-grown dots is somewhat larger; however, other characteristics such as the composition of the dots' uppermost layers, the interlayer spacing, and the bowing of the atomic layers are similar. (C) 2011 American Institute of Physics. [doi:10.1063/1.3599063]