Dynamical diffraction effects on higher-order laue zone lines in CBED patterns of semiconductors

We studied the dynamical diffraction effects on the defect lines of higher-order Laue zone reflections (HOLZ lines) in bright field disks of convergent-beam electron diffraction (CBED). The positions of the HOLZ lines were confirmed experimentally to deviate by a small amount from the positions expected from the kinematical approximation. The amount of line shift is represented by the corresponding deviation of the accelerating voltage Δ E. In the case of [111] incidence, one HOLZ reflection can generate two lines with negative and positive values of Δ E. Calculations based on the dynamical diffraction theory clarified that the HOLZ lines with negative and positive Δ E arise from the first and second branches of the zeroth-layer dispersion surface, respectively. Either, or occasionally both, of the lines is observed in the HOLZ pattern, depending upon which branch is dominantly excited. The dependency of Δ E on the material species and thickness of specimen and on the zone axis is discussed in detail for Si, Ge and some III-V compound semiconductors.