The properties of the dark-field diffraction contrast of a dislocation that was imaged by weak reflections were analyzed by means of experiment and dynamic calculations. Near to the center of the contour of a weak reflection, g, the contrast of a dislocation appeared as a multiple image. The number of images was directly related to the magnitude of the inner product, g•b. Upon departing from the center of the reflection contour, the main dislocation contrast shifted to one side of the real dislocation line; depending upon the sense of g•b. These properties provided a new method for the determination of g•b and the Burgers vector; including both the latter’s direction and magnitude. Multiple images of a single dislocation in GaAs, for g•b= 1, 2, 3, 4, 5 and 6, were considered systematically for the first time, and the complete Burgers vector was identified by means of diffraction contrast experiments.

J.Feng, Z.Zhang, X.Duan, Q.Xu: Philosophical Magazine Letters, 1996, 74[3], 195-202