Figure 2
From: Migration mechanism of a GaN bicrystalline grain boundary as a model system
Step migration of the bicrystalline GB.
(a) Low-magnification overview taken after annealing at 500 °C for 86 min of the GB region between the grains with the surface normal directions of [2 −1 −1 0] and [1 0 −1 0]. A basal-plane stacking fault is seen below the GB, which is used as a gauge of the step and GB migration distances throughout the present study. The [0001] direction indicated by the white arrow is common to both the grains. (b) Enlarged HRTEM image of the GB as in (a). The inset is a simulated HRTEM image obtained by employing the multislice method within the MacTempas software package23 at a defocus of 16 nm and a specimen thickness of 23 nm based on an atomic model. The atomic positions in the model (blue for gallium and yellow for nitrogen) were determined by contrast matching between the experimental image and simulated images at different defocus and specimen thickness values. For more details on the determination of the GB position, see Supplementary Information (Fig. S1). (c) is taken 20 s after (b).
