Growth of ZnO nanorods on A-plane (11(2)over-bar-0) sapphire by metal-organic vapor phase epitaxy

The growth mode of ZnO on a-plane (11 (2) over bar0) sapphire in metal-organic vapor phase epitaxy exhibited stronger tendency toward three-dimensional nucleation at lower temperature (less than or equal to700degreesC) and toward two-dimensional layered growth at higher temperature (900degreesC), resulting in the formation of rods and films, respectively. ZnO nanorods with diameters smaller than 10 nm were fabricated at the appropriate precursor flow rate and growth temperature. Blue shift of emission from free excitons, in a photoluminescence spectrum was observed for the nanorods, particularly for those grown at 400degreesC. Because the diameters of those nanorods were sufficiently small for quantum confinement, the blue shift was reasonably attributed to quantum size effects.