PRINCIPLES OF THE MEASUREMENT OF COMPOSITION AND STRAIN IN EPITAXIAL LAYERS USING CONVERGENT-BEAM ELECTRON-DIFFRACTION

A theoretical model is developed which allows the deformation of a mismatched epitaxial layer to be obtained using the position of HOLZ lines in the blight field disk of a CBED pattern. By measuring the position of the lines relative to those in a reference sample, it is possible to obtain a solution for the deformation of the material with respect to the reference. However, it is found that it is not possible to solve for both the lattice parameter and strain of the material in the general case. This means that there must always be some assumption made about the state of strain in the TEM sample before a lattice parameter measurement can be obtained.