Strain maps at the atomic scale below Ge pyramids and domes on a Si substrate

In this letter, the strain field below uncapped Ge islands of a different shape on a Si(001) substrate is estimated by molecular dynamics simulations at a realistic scale. Comparison to the Fourier transform maps of transmission electron micrographs, recently reported in literature, shows a very good agreement. We point out that the complex deformation in silicon, just below the edges of the Ge islands, is far from being uniaxial. The stress distribution generated by such a strain determines the range of interdot repulsion. (C) 2002 American Institute of Physics.