Influence of nitrogen annealing on structural and photoluminescent properties of ZnO thin film grown on c-Al2O3 by atmospheric pressure MOCVD

ZnO thin films on (0 0 0 1) sapphire large area substrates (Φ50×0.43 mm) have been deposited by atmospheric pressure MOCVD. To investigate the effects of post-annealing treatment on the structural and luminescent properties of ZnO thin films, films have been annealed in nitrogen at various annealing temperatures from 400 to 800 °C. The best crystal quality of ZnO films was obtained with annealing temperatures up to 800 °C by measuring the FWHM of (1 0 2) and (0 0 2) peak. At annealing temperature above 700 °C, the intensity of UV (377 nm) peak is greatly decreased, and the deep-level emission peak (500 or 500-525 nm) is enhanced. The study of structural and luminescent properties of ZnO thin films annealed in nitrogen shows that the crystallinity of ZnO thin films is not easily degraded by oxygen vacancies, or say, the deficient oxygen nonstoichiometric ZnO single crystal films may be of better crystallinity as that of the deficient nitrogen nonstoichiometric single crystal GaN films reported.