Increased surface ordering of InAs island arrays using a multidot column subsurface structure

We report experimental evidence of improved in-plane self-organization resulting from vertically stacked self-assembled InAs islands in a GaAs matrix. Samples under investigation were grown by molecular beam epitaxy in Stranski-Krastamow growth mode and consisted of one, five, ten, and twenty layers of coherently strained islands of InAs with all but the last layers covered with GaAs. We have studied atomic force microscope images of the sample surface morphology and performed real space, as well as Fourier space image processing. Along with the evolution of island size and long range surface roughness, we clearly observe the onset of in-plane island ordering with stacking.