Controlled Growth And Photoluminescence Properties Of ZnO Nanorod Arrays

Zinc oxide is a Ⅱ-Ⅵ semiconductor withwide band gap of3.37eV and largeexciton binding energy of60meV at room temperature. It has aroused interesting ofstudy in the UV emission field, and can be applied in many aspects for researchingand application. One dimensional （1-D） ZnO nano-materials have unique crystal andoptical properties. It remains hot in the optical emission field. Controlled growth ofZnO nanorod （NR） arrays can be perfectly used in energy transition, optical catalysis,sensors et al. it is widely studied in the controlled growth and optical properties ofZnO nanorod arrays.Hydrothermal method is commonly used in fabricating ZnO nanorods. It hasadvantages in low-cost and simple synthesis in contrast to other methods. Nanorodswith different aspect-ratio and optical properties can be synthesized throughcontrolling the precursor concentration ratio and reaction time et al. Optical propertiesof ZnO can be improved by impurities incorporating or surface decorating, whichmakes it excellent materials in optoelectronics. Sulfidized ZnO nanorod arrays can beobtained by chemical method, among which sulfidizing process is the mostconvenient method. In a sulfidizing process, the synthesized ZnO nanorod arraysshould be immersed into Na2S aquesous solution and react in a water bath condition.The sulfide element, which can be incorporated into the ZnO nanorod, could influencethe optical properties of ZnO nanorod arrays.The major works in this paper list as following:（1） ZnO NRs arrays have been fabricated by hydrothermal method. The ratiovariation of Zn（Ac）₂·2H₂O:HMT in the precursor could influence the morphology andoptical properties of the ZnO nanorod arrays. In our experiment, the concentrationratios were set at3:1,2:1,1:1,1:2and1:3. X-ray diffraction （XRD） measurement,scanning electron microscope （SEM） measurement, photoluminescence properties（PL） measurement have been carried out to characterize the ZnO nanorod arrays. Asthe concentration ratio of Zn（Ac）₂·2H₂Oto HMT decreases from3:1to1:3, thediameter of ZnO nanorod decreases. Smooth hexagonal ZnO crystals are obtainedwhen the ratio of Zn（Ac）₂·2H₂Oto HMT equals1. Besides the peak of （002）,diffraction peaks of （100） and （101） have also been measured. The ZnO nanorod arrays have better crystal quality and arrange more uniformly.（2） Controlling the ratio of Zn（Ac）₂·2H₂O:HMT as1:1, reaction time was tuned.And the product was characterized by XRD, SEM and PL. The growth process ofZnO nanorod arrays in a hydrothermal method was studied. The intensive propertiesand length of ZnO NRs increase as the reaction time increases from1h to2.5h. Butthe disorder of ZnO nanorod arrays becomes more and more obvious..（3） Sulfidized ZnO nanorod arrays can be obtained by thermal sulfidizingprocess. Three emission bands including UV, blue and green range are measured forthe ZnO nanorod arrays. The little UV emission enhancement of ZnO nanorod arrayscan be obtained by sulfidizing the defects of ZnO including surface defects andoxygen defects.