| Zn-based wide band gap semiconductor with large exciton binding energy is a compound semiconductor material located in the II-VI family.Nano-ZnO is a n-type semiconductor with a band gap 3.37eV,and Nano-ZnS is a good performance fluorescent material with band gap in the 3.66eV3.8eV range.Therefore,which are considered ideal optoelectronic materials.In recent years,composite semiconductor materials have gradually become a development trend in exploring the excellent performance of semiconductor materials,two or more than two nano-structural units are effectively assembled to optimize the performance of the material.In this paper,the preparation,characterization,field emission and optical properties of Nano-ZnO,Mn/ZnO and ZnO/ZnS composites are explored,and then the influence of process parameters on the structure,morphology,field emission and optical properties of Nano-ZnO materials is analyzed,and the key words are expressed as follows:1.Nano-ZnO with different morphologies was fabricated by hydrothermal method and orthogonal test.XRD test shows that samples are pure phase Nano-ZnO crystal with good crystalline quality of hexagonal wurtzite structure.And then,the flower-like Nano-ZnO is selected to deposit uniform field emission cathode coating on Ti substrate and Ni substrate by electrophoresis and spin coating respectively.The results indicate that the Nano-ZnO coatings deposited on the Ti substrate and Ni substrate by electrophoresis present the flower morphology.But compared with the Ti substrate,the cathode coating on the Ni-substrate surface is densely distributed and tips of the field emitter are more numerous,besides,the particles of the coating on the surface become finer and more uniform.In addition,the Nano-ZnO cathode deposited on the Ni substrate shows relatively stable field emission characteristic;ZnO coating deposited on Ni substrate by spin coating method is uniform and has prominent emitter tips,the cathode field emission current density increases with increasing of doped-ZnO powder and turn-on electric field decrease gradually.Finally,the field emission mechanism of the coating is discussed.2.Mn-doped ZnO materials were synthesized by hydrothermal reaction at low temperature,and then the morphology,structure and luminescence properties of the samples were characterized by SEM,XRD,EDS and PL respectively.The results show that the product prepared is crystal with hexagonal wurtzite structure.EDS spectra confirm that Mn element is successfully incorporated into the Nano-ZnO crystal,besides,diffraction peak intensity of crystal decreases,and crystal size gets smaller for part of the Zn2+is replaced by Mn2+,which makes morphology of samples changed from nanorods to nanowires.The PL spectra shows that the fluorescence intensity of emission peak in the visible light region is significantly enhanced after doping Mn element,and the bathochromic shift phenomenon in the emission peak is found.Finally,the luminescence mechanism of the sample is analyzed.3.ZnO/ZnS composites with different morphologies were synthesized by hydrothermal reaction,which uses Zn?CH3COO?2·2H2O and CH3CSNH2 as Zn source and S source respectively as well as ZnO is a precursor solution.The concentration of S elements in solution gradually increases via adjusting the content of CH3CSNH2.The results indicate that ZnO/ZnS complex structure is transformed from the original hexagonal wurtzite to sphalerite structure with the increase of the concentration of S elements,and the morphology of the product also changes from the initial microsphere to the nanosheets structure.However,when the molar concentration ratio of the Zn2+to the S2-in the solution is 1:4,the sample exhibits better fluorescence characteristics.Meanwhile,the photoluminescence property of ZnO/ZnS is better than ZnO. |
PDF Full Text Request