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(Color online) Schematic representation of the two possible (GaAs) interfaces: (a)–(c) Chain model and (d)–(f) shadow model, viewed along [(b) and (e)] and  [(c) and (f)], respectively. The spacing labeled “” marks the spacing between the last In–Ga column and the As column in the first ErAs layer.
(Color online) HAADF/STEM image of the interface viewed along . The overlay represents atomic column positions consistent with the chain model and the observed image contrast. Large blue disks represent As and small red and yellow disks represent Er and Ga, respectively.
(Color online) HAADF/STEM image of (a) the and (b) the viewed along , i.e., perpendicular to the viewing direction in Fig. 2. The overlay in (a) shows the atomic column positions identified from the image. Arrows mark the positions of the last row of Ga (Ga–In) atoms in the zinc blende semiconductor.
(Color online) Intensity profiles (averaged over a 0.05 nm wide area) across HAADF/STEM images of interfaces recorded from different regions of the TEM sample. The background (thick dashed lines) is greater in the ErAs relative to the . The block arrows indicate the positions of As columns. The column spacing labeled “” marks the spacing between the last In–Ga column and the As column in the first ErAs layer [see also Fig. 1(b)]. (a) Thicker sample region, showing an column intensity ratio of about 2.9 and (b) thinner region that shows an intensity ratio of columns close to 3.4. The expected intensity ratio is 3.4, if the image intensity is proportional to .
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