Quantitative Energy-Filtered Convergent Beam Electron Diffraction-Matching Theory to Experiment

Quantitative Convergent Beam Electron Diffraction (CBED) is now established as a means of accurate loworder structure factor determination. Using energy-filtered zone-axis CBED patterns it has been demonstrated that the 111 structure factor at the <110> zone-axis in Si can be measured to better than 0.1%. In order to achieve this accuracy, it is essential to have a full understanding of the zone-axis pattern matching technique (ZAPMATCH) and the microscope system on which the data is acquired. Before any patterns can be analyzed, the effects of the detector system [in our case a Gatan Imaging Filter (GIF)] on the recorded intensities must be understood. Consideration must also be given to the number of structure factors that can be refined from any given data set. Our recent implementation of ZAPMATCH on a Topcon 002B with GIF provides an illustrative example of the former. Measurements of the low-order structure factors of nickel serve to demonstrate the latter.