Volume 93, Number 6, March 2011
|Number of page(s)||6|
|Section||Condensed Matter: Structural, Mechanical and Thermal Properties|
|Published online||28 March 2011|
Composition and strain of Ge domes on Si(001) close to the dome/susbtrate interface
IQFR-CSIC - Madrid, Spain, EU
2 Aix-Marseille Université, IM2NP-CNRS, Faculté des Sciences et Techniques - F-13397 Marseille Cedex, France, EU
3 ICMA, Departamento Fisica de la Materia Condensada, CSIC-Universidad de Zaragoza - Zaragoza, Spain, EU
4 LMGP, Grenoble INP-Minatec - Grenoble, France, EU
5 CEA-UJF, INAC, SP2M - Grenoble, France, EU
6 Institut für Halbleiter- und Festkörperphysik, Johannes Kepler Universität Linz - Linz, Austria, EU
Accepted: 23 February 2011
Strain fields and composition gradient in epitaxial Ge dome-shaped islands grown on Si(001) substrates are determined by combining grazing-incidence multiwavelength anomalous diffraction and grazing-incidence diffraction anomalous fine-structure spectroscopy. This unique combination, together with numerical X-ray diffraction calculations carried out in the frame of the distorted-wave Born approximation with a structural model obtained by molecular dynamics, is shown to probe unambiguously the Ge composition even in the difficult region close to the island/substrate interface and to elucidate the vertical compositional profile inside the dome-shaped islands. A rather abrupt chemical composition profile close to the interface and a slight increase of the average Ge composition from the base to the top are observed for islands grown at a temperature of 650 °C. These experiments provide unique fundamental knowledge on the mechanism of Si-Ge intermixing during island growth, clarifying and quantifying the effects of growth conditions and morphology on the structural local properties of the nano-islands.
PACS: 61.46.-w – Structure of nanoscale materials / 61.05.-a – Techniques for structure determination / 81.07.Ta – Quantum dots
© EPLA, 2011
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