Impact of column bending in high-resolution transmission electron microscopy on the strain evaluation of GaAs/InAs/GaAs heterostructures

The accuracy of strain profiles obtained by a quantitative analysis of latt ice fringe spacings from high-resolution micrographs is discussed. Focusing on highly lattice mismatched GaAs/InAs/GaAs heterostructures the local str ain distribution of the layers is calculated by finite element simulations to determine the atom positions in elastically relaxed transmission electro n microscopy specimens. By analysing simulated images a significant decoupl ing between the layer structure and the contrast pattern motifs is found fo r relevant imaging conditions, which may result in an incorrect determinati on of strain profiles and layer compositions when examining experimental mi crographs. (C) 2000 Elsevier Science B.V. All rights reserved.