Dresden 2009 – scientific programme

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DS: Fachverband Dünne Schichten

DS 1: Thin Film Characterisation: Structure Analyse and Composition (XRD, TEM, XPS, SIMS, RBS, ...) I

DS 1.4: Talk

Monday, March 23, 2009, 11:00–11:15, GER 37

Formation of Ge NC’s out of (GeO_x-SiO₂) superlattice structures — •Nicole M. Jeutter, Manuel Zschintzsch, Johannes von Borany, and Carsten Baehtz — Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, 01328 Dresden, Germany

Semiconductor Nanocrystals (NC), consisting only of a few hundred of atoms, are of great interest for new generations of light emitters, non-volatile memories or high efficiency solar cells [1]. However, it remains a remarkable challenge to achieve a high density (>10¹²cm²) of equal-sized, small (<5 nm) NC’s of Ge or Si embedded in dielectric films. In this study we present the fabrication of Ge-NC’s by decomposition of GeO_x (1<x <2) out of a (GeO_x -SiO₂) superlattice structure (SL). The SL was grown by dual reactive DC magnetron sputtering from elemental targets. Different Ge/O ratios in the SL structures were realized by the variation of oxygen flow and deposition temperature. Using in-situ x-ray reflectivity and grazing incidence diffraction at the CRG Beamline ROBL at ESRF we studied the deposition of the SL and the Ge NC’s evolution during subsequent annealing. Depending on the GeO_x stoichiometry closed nanocrystalline films or separated Ge NC’s with grain or particle sizes between 2-5 nm have been obtained with grazing incidence x-ray diffraction. The size of the NC’s can be tuned with thickness of the GeO_x sublayer, its density exceeds 10¹²cm².

[1] A.Rogach (ED.), Semiconductor nanocrystal quantum dots, Springer, Wien 2008, ISBN 978-3211752357