MOCVD growth and properties of ZnO films using dimethylzinc and oxygen

The ZnO films were grown by low pressure metal-organic chemical vapor deposition (LP-MOCVD) using dimethylzinc (DMZn) and oxygen. The as-grown film has strong (0002) oriented characteristic, containing the chain-like network grains in small sizes, A well-resolved shoulder emission at 3.03 eV in the photoluminescence (PL) spectra has been ascribed to the interstitial zinc in the crystal, implying a serious oxygen deficiency state of the MOCVD growth, in good agreement with the analysis of XPS results. Post-annealing of the films leads to the remarkable improvement of the structure, morphology, components and optical properties. Large hexagonal columnar grains were then observed by atomic force microscope (AFM). The luminescence efficiency was enhanced greatly due to the reduction of the nonradiative defects. Meanwhile, chemisorbed oxygen gives rise to surface acceptor states, resulting in the different radiative recombination. Photoluminescence excitation measurement shows good agreement with the above conclusions.