DOI: 10.1209/epl/i2003-00513-x
Europhys. Lett., 63 (2) , pp. 268-274 (2003)

On the driving forces for the vertical alignment in nitride quantum dot multilayers

V. Chamard^{1, 2}, T. H. Metzger¹, M. Sztucki¹, V. Holý³, M. Tolan², E. Bellet-Amalric⁴, C. Adelmann⁴, B. Daudin⁴ and H. Mariette<sup>4

1</sup>  European Synchrotron Radiation Facility - BP 220, 38043 Grenoble Cedex, France
²  Experimentelle Physik I, Universität Dortmund - Otto Hahn Str. 4, 44221 Dortmund
³  Institute of Condensed Matter Physics, Masaryk University 61137 Brno, Czech Republic
⁴  CEA-CNRS group, "Nanophysique et semiconducteurs" Département de Recherche Fondamentale sur la Matière Condensée, CEA/Grenoble 17 rue des Martyrs, 38054 Grenoble Cedex 9, France

chamard@physik.uni-dortmund.de

(Received 6 January 2003; accepted in final form 14 May 2003)

Abstract
The layer-to-layer vertical alignment of quantum dots in multilayers is quantified as a function of the spacer layer thickness and the number of bilayers, using grazing-incidence X-ray scattering. Although the density of dots is comparable to the density of (0001) threading dislocations, we observe that the strong vertical ordering is strain induced by the buried dots. Elasticity theory calculations confirm this experimental result and explain the observation of the exceptionally strong vertical alignment in nitride compared to other classical systems.

PACS
68.55.Ac - Nucleation and growth: microscopic aspects.
61.10.Eq - X-ray scattering (including small-angle scattering).
61.72.Lk - Linear defects: dislocations, disclinations.

© EDP Sciences 2003