The effect of scanning jitter on geometric phase analysis in STEM images

Geometric phase analysis (GPA) is a useful method to map strain distribution in atomically resolved scanning/transmission electron microscopy (S/TEM) images. Nevertheless, the inevitable periodic jitter of electron probe in STEM along the scanning direction due to the interference of electric power supply, including grounding, can give rise to major artifacts, as evidenced by the appearance of satellite spots surrounding all main peaks in the power spectrum of the images. Here we reveal the origin of the image artifacts related to the probe jitter by mapping the image distortion component epsilon(xx) using the GPA algorithm. The effect is verified by introducing a periodic displacement field to a STEM image simulated from a perfect crystal structure, and the calculated epsilon(xx) maps show very good agreement with the experimental observations. Based on the quantitative analysis of the images distortion, we propose and test a feasible strategy to eliminate the effect of probe jitter from STEM images. Successful examples illustrate that the approach can help improve the accuracy in quantification of STEM images.