Chemical composition and strain distribution of InAs/GaAs(001) stacked quantum rings

4 páginas, 4 figuras.-- Proceedings of the 14th Conference, April 11–14, 2005, Oxford, UK.-- A. G. Cullis and J. L. Hutchison (eds.).The strain and composition distributions of InAs/GaAs(001) stacked self-assembled quantum rings (QRs) grown by MBE have been analyzed. Transmission electron microscopy (TEM) images revealed a high degree of vertical arrangement of quantum rings for samples spaced by a GaAs spacer layer thickness ts < 6 nm. The peak finding method was applied to high resolution transmission electron micrographs in order to plot strain maps, revealing that the higher strained areas were in the ring core and close to it. The existence of another layer with similar strain to the wetting layer was also clear from the peak finding strain analysis. The transverse compositional profiles taken from 002 DF TEM images show the existence of In-rich regions within the nano-rings and an In(Ga)As well defined layer surrounding them, which is formed during the growth process.This research was supported by Spanish MCyT under project NANOSELF (TIC-2002-04096- C03-02), Junta de Andalucía (PAI research group TEP-0120) and network of excellence SANDiE (Contract NMP4-CT-2004-500101 of the VI European Framework Programme).TEM measurements were carried out in the DME-SCCYT, University of Cádiz and UCM.Peer reviewe