All the diffraction patterns are indexed to the hexagonalwurtzite structure
(JCPDS card, no. 65-3411). The sharp diffraction patterns indicate
that the prepared ZnO nanocrystals are in their high crystallinity. Furthermore,
no other impurity peak patterns were detected with the detection
limit, which supports the idea that the prepared ZnO nanorods
are pure ZnO. In comparisonwith the diffraction patterns fromthe ZnO
seed films in Fig. 8 (a), the (002) diffraction peak at 34.65° is strongly
enhanced in Fig. 8 (b), which is distinct from that of the ZnO substrate
film (a). The result demonstrates that the preferential orientation of
ZnO nanorod growth is c-axis, showing that the ZnO nanorods grow
fastest perpendicular to the substrate surface. Furthermore, the result
is well matched with the corresponding SEM image in the inset.