Situ Growth And Luminescent Properties Of ZnO Nanocrystals In The Amorphous Silica

As a wide band gap semiconductor nanomaterial, ZnO nanocrystals havebeen broadly applied to optoelectronic devices because their potential advantages suchas simple and low-cost preparation route and controllable growth process. For itsluminescence properties, there is an important issue for controlling the size of ZnO particlesand consequently it’s the color difference between sizes. In this paper, ZnO nanocrystals weresitu growth in the SiO₂network which was studied in detail. The defect emissioncharacteristics corresponding to particles size and related luminescence mechanism wereproposed and discussed.For its equivalent radius with Zn²⁺, Mg²⁺doped ZnO was prepared and the influence ofMg²⁺on the defect luminescence of ZnO was studied. We found that Mg-doped ZnOnanocrystals show the red shift in absorption edge which is due to band-gap narrowing effect.Then Mg²⁺doped ZnO nanocrystals was modified by SiO₂which show the blue shift inabsorption edge which is due to the quantum confinement effect and moss-burstein effect.With the reaction time enhancing, the absorption edge exbihited red shift which is consideredas the influence of Mg-doped on the crystal field of ZnO nanocrystals.P-type NiO was prepared by ultrasonic and then annealing process. With modified bydifferent amount p-type NiO, ZnO@NiO composite materials was formed and theirluminescent spectra were gently compared. PL spectra showed that ultraviolet emission ofZnO nanocrystals was enhanced gradually with the increased amount of NiO, which is due tothe reduced radiationless transition center of ZnO nanocrystals surface and the increasedexciton concentration of ZnO nanocrystals.