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 consecuti ve Stranski-Krastanov layers of Ge buried in Si by molecular beam epitaxy. Quantitative evaluation of the micrographs has revealed the critical Si int erlayer 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 on e buried Ge layer to the next. (C) 1999 American Institute of Physics. [S00 03-6951(99)03502-0].