Fine details in satellite HOLZ reflection discs of CBED from a GaAs/AlAs multilayer

Abstract

Fine details of satellite higher-order Laue zone (sHOLZ) reflection discs from a GaAs/AlAs multilayer in plan view are observed and investigated. Computer simulation based on the dynamical theory of electron diffraction shows good agreement with the experimental observations. Apart from the two lines reported previously, some weak lines and a few other features in sHOLZ reflection discs are found and investigated. The investigation confirms the previous two-line explanation and also reveals the origin of the additional weak lines and the other features. The weak lines are due to the interference between Bloch waves, and their location depends on specimen thickness. Some other features are determined to be caused by multiple diffraction from neighbouring sHOLZ reflections. The phenomenon of the interruption of lines in sHOLZ reflection discs, in comparison to the lines in fundamental higher-order Laue zone (fHOLZ) discs, originates mainly from sHOLZ reflection coupling. Furthermore, intensities of sHOLZ reflections are shown to depend on their structure factors rather than on the excitation of their corresponding fundamental reflections. Details of the computer simulation are given. Finally a simple method, not relying on computer simulation, to identify the lines in sHOLZ reflections is presented.