Growth of ZnO Nanorods on A-Plane (1120) Sapphire by Metal-Organic Vapor Phase Epitaxy

The growth mode of ZnO on a-plane (11 0) sapphire in metal-organic vapor phase epitaxy exhibited stronger tendency toward three-dimensional nucleation at lower temperature (≤700°C) and toward two-dimensional layered growth at higher temperature (900°C), 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 400°C. Because the diameters of those nanorods were sufficiently small for quantum confinement, the blue shift was reasonably attributed to quantum size effects.