ZnO nanorods were epitaxially grown by metalorganic chemical vapour deposition (MOCVD) on sapphire (0001) and substrates. The nanorods were elongated along the ZnO c-axis which was parallel to the substrate normal. Good alignment among the rods was achieved both in the length direction and in the in-plane orientations. The line width of bound exciton emissions was  meV at low temperatures. Emissions due to free excitons were observed from low to room temperature. Biexciton emissions were observed up to  K. The band edge emission at room temperature was found to be a mixture of emissions due to free excitons and other impurity-related emissions, indicating that care must be taken when assigning the emission peak at higher temperatures.

Three-dimensional (3D) Ta 2 O 5 /SiO 2 photonic crystals in the visible-violet spectral region are fabricated by an auto-cloning technique on patterned substrates with triangular lattice configurations and their in-plane (the stack XY plane) optical properties are studied. Reflection measurements by normal incidence of light on to the cleaved facet of the photonic crystal reveal maximum reflections at certain photon energies. Comparison with calculated band structure demonstrates that the reflection peaks are either due to the photonic bandgap (PBG) within which the light propagation is forbidden, or due to heavy photons associated with flat bands. A two-step deposition method is adopted to insert luminescent rhodamine 590 into the photonic crystal and the emission property is strongly modified by the photonic crystal. Possible applications of such 3D photonic crystals in optical components are discussed.