In summary, ZnO nanorods with in-situ controllable diameters
ranging from 30 nm to 200 nm have been synthesized by hydro-
thermal method on sol_gel derived ZnO seeds/p-Si substrates. The
effect of annealing temperature of ZnO seed layers on the
morphological, structural and optical properties were investigated.
All ZnO nanorods show a strong diffraction peak at 34.781
corresponding to ZnO (002) plane and no impurity phase was
observed. Photoluminescence (PL) spectrum study shows that all
samples possess strong near band edge emissions at 392 nm and
defect related broad visible emissions centered at 550 nm. With
increasing ZnO seeds annealing temperature, the morphologies of
ZnO nanorods change from tapered needle- to hexagonal-like
structures and the visible emission intensity decreases gradually
as decreases of oxygen vacancies at high annealing temperature.