A study of the relationship between lattice fringes and lattice planes in electron microscope images of crystals containing defects

Abstract

Recently several very clear lattice fringe images have been published in which the perturbing influence of lattice defects is evident in the form of bending and terminating fringes. Detailed analyses of these images have been given, based on the assumption that there exists a one-to-one correspondence between fringe distribution and lattice plane distribution. From studies of the properties of calculated images, doubt has been cast upon the validity of such a straightforward interpretation. Analysis of these calculated images suggested that a change in the diffraction geometry could produce changes in the number of terminating fringes and in the fringe bending which were not related to the lattice plane geometry in any simple way. In this paper a summary of the predicted image properties arising from the calculations is given. By examining lattice fringe images of inclined dislocations in deformed Ge, these properties are verified experimentally. As a result it is shown that it is not correct to analyse fringe images on the basis of a one-to-one correspondence with lattice planes because the fringe distribution and number of terminating fringes are dependent upon the diffraction geometry.