Fig. 3: STM empty-state (group-III related) filtered image of GaAs (a) and GaInP (b). Both images are low- and high-passed filtered to reduce pixel-to-pixel noise and flatten the image, respectively. Individual atomic positions are marked in both images. (a) shows the area of GaInP surrounded by the Green box in Fig. 1. This is an area of about 14 atoms by 23 atoms. Note the uniform appearance of the atoms. The open rectangle mark the Ga atoms. (b) shows the area of GaInP surrounded by the Red box in Fig. 1. This is an area of about 27 atoms by 45 atoms. Note the bright and dark appearance of the atoms. The open rectangles mark the dark atoms with height less than 2 B/W units as Ga, and open diamonds mark the bright atoms with height greater than 5 B/W units as In.

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