(a)
(b)
(c)
(d)
Figure 1: SEM images of the as-grown ZnO samples on the Al substrate. (a) Large-area view of the ZnO nanoflakes on the Al substrate, (b) top images of the ZnO nanorod arrays and (c) high magnification ZnO nanorod arrays, and (d) side views of the ZnO nanorod arrays.