Optimized Growth of ZnO Nanowires and Nanorods Using MOCVD

ZnO NWs were grown on Si (111) and Al₂O₃ substrates using MOCVD. ZnO (002) NWs on Si were randomly orientated while the NWs grown on sapphire were mostly vertically aligned as evident from scanning electron microscope images. The c-axis lattice constant corresponding to ZnO (002)/Si(111) demonstrated a dominant peak at 34.47°(2θ) attributed to ZnO along (002) with a FHWM of 0.0948°(θ) with corresponding c and a-lattice axes constants of 5.1996Å and 3.2456Å, respectively. The c-axis lattice constant for ZnO/sapphire was estimated to be 5.205Å resulting in an out of plane strain of only 0.03%. Photoluminescence of ZnO nanowires grown on sapphire shows absorption peaks associated to exciton-exciton recombination and native defect such as zinc interstitial. In the case of NWs grown on Si, only exciton to exciton recombination was observed.