From the SEM photographs,
it is clearly noticed that ZnO nanorods have a welldefined
hexagonal facet. They grow perpendicular to
the substrates in a well-defined manner on Si substrate.
On sapphire, the nanorods are found to grow
aligned in two directions: vertical to the substrate as
well as inclined to a particular angle. In both cases,
the grown nanorods are in high density and uniform
over a large area