Wahra, Assma, Tan, C. -H., Xie, J., Vines, P. and Beanland, R. (2011) Three-dimensional measurement of composition changes in InAs/GaAs quantum dots. Journal of Physics: Conference Series, Volume 326 (Conference 1). Article number 012048. doi:10.1088/1742-6596/326/1/012048

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Abstract

We present a transmission electron microscope (TEM) analysis of InAs/GaAs quantum dots (QDs) which have been subject to thermal annealing. Annealing produces a significant shift in infrared detector response to longer wavelengths, indicating changes in QD size, composition, or both. A three-dimensional reconstruction of an 'average' QD is obtained by combining compositionally-sensitive dark field 002 TEM images of many QDs, followed by fitting to a structural model assuming cylindrical symmetry. Errors in compositional measurements are estimated, and the validity of the model is assessed by TEM image simulations using 2-beam dynamical electron diffraction theory. As-grown material exhibits an increasing concentration of In towards the top of the QDs, whereas annealed material shows diffusion of indium from the upper part of the QD towards the sides and base. There is no measurable change in the position of the outer interface of the QD.

Item Type:	Journal Article
Divisions:	Faculty of Science > Physics
Journal or Publication Title:	Journal of Physics: Conference Series
Publisher:	IOP PUblishing
ISSN:	1742-6596
Official Date:	2011
Dates:	Date Event 2011 Published
Volume:	Volume 326
Number:	Conference 1
Page Range:	Article number 012048
DOI:	10.1088/1742-6596/326/1/012048
Status:	Peer Reviewed
Publication Status:	Published
Description:	17th International Conference on Microscopy of Semiconducting Materials 2011 4–7 April 2011, Churchill College, Cambridge, UK

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