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Phys Rev Lett. 2013 Dec 27;111(26):265501. Epub 2013 Dec 27.

Strain-induced formation of fourfold symmetric SiGe quantum dot molecules.

Author information

  • 1Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, prospekt Lavrent'eva 13, 630090 Novosibirsk, Russia.
  • 2Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, prospekt Lavrent'eva 13, 630090 Novosibirsk, Russia and Novosibirsk State University, 630090 Novosibirsk, Russia.

Abstract

The strain field distribution at the surface of a multilayer structure with disklike SiGe nanomounds formed by heteroepitaxy is exploited to arrange the symmetric quantum dot molecules typically consisting of four elongated quantum dots ordered along the [010] and [100] directions. The morphological transition from fourfold quantum dot molecules to continuous fortresslike quantum rings with an increasing amount of deposited Ge is revealed. We examine key mechanisms underlying the formation of lateral quantum dot molecules by using scanning tunneling microscopy and numerical calculations of the strain energy distribution on the top of disklike SiGe nanomounds. Experimental data are well described by a simple thermodynamic model based on the accurate evaluation of the strain dependent part of the surface chemical potential. The spatial arrangement of quantum dots inside molecules is attributed to the effect of elastic property anisotropy.

PMID:
24483803
[PubMed]
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