FIG. 3: (a) (f) Topographies measured by STM at six different positions along [001] direction with ∼ 5 µ m distance apart. Each STM image has dimension of 300 nm × 300 nm.The measured positions were indicated roughly in the (g) SEM image near sample edge (top of (g)). of dislocations as indicated by a horizontal arrow. Figure 4 (b) and (c) show the higher- magnification SEM and STM images, respectively. Dislocations, as indicated with horizontal arrows, were clearly observed. Besides the dislocations, a more dramatic height change was seen in fig. 4 (a) (around the middle of the image). This dramatic height change separates two very different topographies: smooth (below) and textured (above) regions. The STM images scanned in these two regions are shown in fig. 4 (d) and (e), at positions indicated by dashed arrows. Note that, again, the STM arrows do not indicate the exact positions for the STM images, but the relative positions reference to the dramatic height change, which can 5