Germanium “quantum dots” embedded in silicon: Quantitative study of self-alignment and coarsening

We report on experiments aiming to produce Ge quantum dots embedded in Si. Employing cross-sectional transmission electron microscopy, we have studied the misfit stress-induced self-alignment of islands belonging to consecutive Stranski–Krastanov layers of Ge buried in Si by molecular beam epitaxy. Quantitative evaluation of the micrographs has revealed the critical Si interlayer thickness below which the island positions in successive Ge layers begin to correlate. Moreover, we have quantitatively analyzed the influence of the Si interlayer thickness on the coarsening of the Ge islands from one buried Ge layer to the next.