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 lattice fringe spacings from high-resolution micrographs is discussed. Focusing on highly lattice mismatched GaAs/InAs/GaAs heterostructures the local strain distribution of the layers is calculated by finite element simulations to determine the atom positions in elastically relaxed transmission electron microscopy specimens. By analysing simulated images a significant decoupling between the layer structure and the contrast pattern motifs is found for relevant imaging conditions, which may result in an incorrect determination of strain profiles and layer compositions when examining experimental micrographs.