Reading the footprints of strained islands Journal Article

Author(s): Rastelli, Armando; Stoffel, Mathieu; Katsaros, Georgios; Tersoff, Jerry; Denker, Ulrich; Merdzhanova, Tsvetelina; Kar, Gouranga S; Costantini, Giovanni; Kern, Klaus; Von Känel, Hans; Schmidt, Oliver G
Article Title: Reading the footprints of strained islands
Abstract: We report on recent advances in the understanding of surface processes occurring during growth and post-growth annealing of strained islands which may find application as self-assembled quantum dots. We investigate the model system SiGe/Si(0 0 1) by a new approach based on "reading the footprints" which islands leave on the substrate during their growth and evolution. Such footprints consist of trenches carved in the Si substrate. We distinguish between surface footprints and footprints buried below the islands. The former allow us to discriminate islands which are in the process of growing from those which are shrinking. Islands with steep morphologies grow at the expense of smaller and shallower islands, consistent with the kinetics of anomalous coarsening. While shrinking, islands change their shape according to thermodynamic predictions. Buried footprints are investigated by removing the SiGe epilayer by means of selective wet chemical etching. Their reading shows that: (i) during post-growth annealing islands move laterally because of surface-mediated Si-Ge intermixing; (ii) a tree-ring structure of trenches is created by dislocated islands during their "cyclic" growth. This allows us to distinguish coherent from dislocated islands and to establish whether the latter are the result of island coalescence.
Keywords: Self-assembled quantum dots; Ge/Si; Morphological transitions; Selective etching
Journal Title: Microelectronics Journal
Volume: 37
Issue 12
ISSN: 09598324
Publisher: Elsevier  
Date Published: 2006-12-01
Start Page: 1471
End Page: 1476
Sponsor: This work was supported by the BMBF (03N8711)
DOI: 10.1016/j.mejo.2006.05.029
Open access: no