The ZnO (0002)
plane has epitaxial planer relation with sapphire along
four particular directions, which includes one (0001)
and three (10¯14) sapphire directions with a rotation
of 120◦ to one another to reduce the in-plane lattice
mismatch[27]. Thus, in addition to the vertical alignment,
the growth of ZnO nanorods can incline to the
sapphire substrate due to their in-plane compatibility
(Fig. 9(b)).