Influence of the self-buffer layer on ZnO film grown by atmospheric metal organic chemical vapor deposition

ZnO films with and without a self-buffer layer were grown on c-plane sapphire substrates by atmospheric metal organic chemical vapor deposition. The influence of the buffer layer thickness, annealing temperature and annealing time on ZnO films has been investigated. The full width at half maximum of the ω-rocking curve of the optimized self-buffer layer sample is only 395 arc sec. Its surface is composed of regular columnar hexagons. After the buffer layer was introduced, the A1 longitudinal mode peak at 576 cm− 1, related to the defects, disappears in Raman spectra. For the photoluminescence, besides the strong donor binding exciton peak at 3.3564 eV, an ionized donor binding exciton and a free exciton peak is respectively observed at 3.3673 and 3.3756 eV at the high-energy side in the spectrum of the sample with the buffer layer.