edfas.org ELECTRONIC DEVICE FAILURE ANALYSIS | VOLUME 26 NO. 1 10 t is the sample thickness, and h is Planck’s constant.[42] Therefore, by analyzing the 4D dataset, the strength of the electromagnetic field can be obtained by measuring the deflection angle via the shift of the transmitted beam at each scan point. Two important components of this framework are measuring the disk shift as precisely as possible and understanding the limits of this model. The “rigid-intensity-shift model” or “rigid disk shift” model assumes that the electromagnetic field shifts the diffraction disk in the far-field. While its limits have been discussed in detail elsewhere,[62-64] the basics are that the scattering behavior will depend on the width of the electron beam relative to the phase gradient induced by the electromagnetic potential. If a potential does not induce I. II. (a) (a) (b) (c) (d) (b) Fig. 4 Panel I: Electric field vector color maps of a GaN/AlGaN heterostructure obtained from the [1120] zone axis, with (a) no tilt-scan averaging and (c) tilt-scan averaged DPC images. The scale bars denote 30 nm. (b) and (d) show the line profiles of COM X and COM Y of (a) and (c), respectively. Reproduced with permission from Ref 67. Panel II: A Landau domain structure, comparing results from the same region obtained by (a) traditional COM and (b) analysis based on the circular Hough transform, where the fidelity of the analysis has been improved. Reproduced with permission from Ref 47.
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