Optical Properties Of Doped ZnO (ZYO, ZMEO) And ZnO Nanocomposites (MgO/ZnO,Ag/ZNTs)

ZnO nanomaterials exhibit extensive prospect of application in optoelectronicdevices. How to realize the controllable growth of ZnO nanomaterial is veryimportant for their applications. This dissertation aims to achieve the controllablegrowth of rare-earth （RE） ZnO nanomaterial and ZnO nanocomposites by simplephysical or chemical methods. Their structure, properties and applications areinvestigated in detail by the methods of X-ray diffraction （XRD）, feld emissionscanning electron microscope （FE-SEM）, transmission electron microscopy （TEM）,X-ray photoelectron spectrum （XPS）, photoluminescence （PL） and Raman specture.The major obtained achievements are listed as follow:In the aspect of RE-doped ZnO nanomaterials: Firstly, we synthesized ZYOnanoparticles by a simple sol-gel method. The defect density in the ZnOnanoparticles could be effectively suppressed by the yttrium compensates effect,which strongly improved the luminescent performance of ZnO nanoparticles.Secondly, Mg²⁺and Eu³⁺co-doping ZnO （ZMEO） with novel flower-likemorphology were prepared by coprecipitationan method. The nanoflowers werecomposed by small petals with the width of200nm and the length of0.5-1μm. Theroom-temperature PL spectrum of ZMEO demonstrated a dramatic enhancement ofred luminescence originating from intra-4f shell transition of5D570-7F2andD0-F0 caused by Mg²⁺codoping, which proved this composite was an attractive candidatesfor nanophotonic device application.In the aspect of ZnO nanocomposites: Firstly, MgO/ZnO core-shell nanorodarrays were synthesized successfully by the hydrothermal growth method. PLemission from the core-shell nanorods showed remarkable enhancement after thedeposition of the MgO layer. Since the MgO/ZnO core-shell nanorods belong to thetype-I heterostructures, both the electrons and holes are confned in the core of thenanorods, as a result, leading to the increase of the photoluminescence intensity inthis system. In addition, another reason for the enhancement of PL emission was thatthe deposition of MgO shell can suppress the surface defects of ZnO nanorods.Secondly, the Ag/ZNTs substrate prepared with a wet-chemical method and DCsputtering represents a new strategy for the creation of SERS-active substrates. Theenhancement factor can be as high as105when using4-mercaptopyridine in solutionas a SERS probe. We soaked the as-prepared sample in the deionized water for30days for the subsequent SERS measurement. It was noted that there is no significantchange in the SERS spectra from the substrate soaked in water for30days. Therelative standard deviations of signal intensities for the major SERS peaks are <7%.The results in this paper not only provides the optimization of growth conditionsof RE-doped ZnO nanomaterials and ZnO nanocomposites, but also obtained someuseful results in the aspect of their luminescence properties, which providestheoretical and experimental basis for the extensive application of ZnOnanomaterials.