BURGERS VECTOR DETERMINATION IN TEM BY USING THE DISLOCATION PARITY ANALYSIS

A modified method of identifying the Burgers vector b is proposed, which is based on the extended analysis of dislocation contrast features. High voltage electron microscopy (HVEM) as well as the computer simulation of the electron micrographs are applied to study the contrast behaviour of mixed dislocations with a large screw component of the Burgers vector under different diffraction conditions in order to check the validity of the method proposed. The analysis of the contrast oscillations along inclined dislocations or the image shift relative to the projection of the dislocation line enables us to determine the 'dislocation parity' P = sgn (l x b . B) while the halo contrast can be used to define the orientation of the 'additional half plane', which is characterized by the normal e = l x b/\l x b\ to the glide plane. The parity and sgn (g . e) analysis enables the unambiguous b vector determination whenever solely one invisibility criterion is applicable. The dislocation parameters in heterostructures are investigated by the above method.