Effect of VI／II Ratio on Structure and Optoelectrical properties of Zinc oxide Thin Films Deposited by Metal—Organic Chemical Vapour Deposition

ZnO thin films with the c-axis orientation on the (0001) sapphire substrate were grown by metal-organic chemical vapour deposition.It was demonstrated that the Ⅵ/Ⅱ precursor flow-rate ratio can influence strongly on the structure and opto-electrical properties.With the increasing Ⅵ/Ⅱ ratio of 130:1,the full width at half maximum of (0002) peak in x-ray diffraction is only 0.184°,the near-band-edge emission enhances remarkably and the intensity ratio of the near-band-edge emission to the deep-level emisson reaches 237:1 in the photoluminescence spectrum.At the same time,the resistivity and mobility increases of 3.28×10^2Ω·cm and 25.3cm^2V^-1S^-1.These facts indicates that the quality of the ZnO thin films could be improved by increasing the Ⅵ/Ⅱ flow rate ratio during the growth.