Quantification of the In-distribution in embedded InGaAs quantum dots by transmission electron microscopy

The In-concentration in InGaAs quantum dots located within a GaAs matrix was determined with the composition evaluation by lattice fringe analysis (CELFA) technique. However, the results obtained with this method cannot account for the three-dimensional shape of quantum dots and their embedding in GaAs. A correction procedure was developed that takes into consideration the shape of the quantum dots and the TEM sample thickness and quantum-dot size. After correction, In-concentration profiles show an increasing Incontent towards the top of the quantum dots which is consistent with the effect of In-segregation and earlier studies using other experimental techniques. Dedicated to Prof. Wolfgang Neumann on the occasion of his 65 th birthday