Films of ZnO were grown onto Si (111) substrates by using a metal organic chemical vapour deposition method. Samples with different stoichiometric composition of Zn and O were obtained by varying the I/VI molar ratio between 3 and 1/3 in precursors. The X-ray photo-electron spectroscopy and photoluminescence results showed that the ultra-violet emission increased with increasing Zn/O composition ratio of the samples. It was suggested that the superfluous Zn atoms piled up at interstitial positions to form Zn interstitial defects. The radiated recombination of the coupling of free excitons with donor Zn interstitial enhances the ultraviolet emission of the samples.

Effect of Zn Interstitials on Enhancing Ultraviolet Emission of ZnO Films Deposited by MOCVD. Z.Zhong, L.J.Sun, X.Q.Chen, X.P.Wu, Z.X.Fu: Chinese Physics Letters, 2010, 27[9], 096101