On the morphology and composition of InAs/GaAs quantum dots

InAs/GaAs quantum dots are analysed in the plan view and in the cross sectional high resolution TEM using the DALI program in order to investigate their morphology and composition. The analysis is based on the comparison of the experimental results with finite element calculations performed with different dot shapes. The simulated strain maps are used to infer about the dot shape; in particular the case in which the thin TEM foil does not include the whole quantum dot is considered. The cross section images are well explained if the dots are round based as suggested by plan view observations. Strain effects that could mimic In segregation are also evidenced. (C) 2002 Elsevier Science B.V. All rights reserved.