The Preparation And The Structural And Optical Properties Of ZnO Nanoparticles Embedded In SiO₂

ZnO is a versatile semiconductor material with hexagona1 wurtzitestructure and has a band gap of 3.3 eV and a 1arge exciton binding energyof 60 meV at room temperature. ZnO has attracted much more interest inthe field of the intbrmation and display like GaN due to the applicationof UV emission. ZnO has some advantages, $uch as resource-richness,cheapness and innocuity. In the past, the structure and optical propertiesof ZnO film has been investigated extensively, in contrast, we are lessknown about the structure and optica1 properties of ZnO nanopartic1esembedded in dielectric tnatrix. By utilizing the wave guide structure ofZnO/SiO, and the optica1 properties of quantum dots, ZnO nanoparticlesembedded in SiO, can decrease the intensity of the photon scattering andse1fabsorption and increase the ZnO nanoparticles UV emission.For the first time, ZnO nanoparticles embedded in SiO, thin fi1mwith the intense ultra-violet emission was fabricated by using electron beam evaporation silica, synchronously thermal evaporation metal zinc on silicon substrate and followed by post-thermal annealing. The results of surface contour analysis, JR spectra, X-ray diffraction spectra and X- ray photoelectron spectra indicated that ZiiO nanoparticles embedded in SiO were formed in oxygen ambient at the annealing temperature of 7000C as the annealing time increased to 2 hours. Micro- photoluminescence spectra showed the existence of a lot of defects, the nonuniform distribution of ZnQ nanoparticles size and the distribution of nanoparticles low density in Si02. As the annealing time increased, the distribution of ZnO nanoparticles in SiO-, gradually displayed mono- distribution of ZnO nanoparticles size. Taking into account the influence of the stress on the energy band of ZnO nanoparticles, the results of the effective mass approximation calculation indicated the formation of ZnO nanoparticles embedded in SiO,. The UV emission of ZnQ nanoparticles at room temperature can be attributed to the free exciton emission. For the first time, high quality ZnQ nanoparticles embedded in SiO, was fabricated by zinc ion implantation (160 keV, 3x10? cm~2) into optical-grade silica substrate, followed by post-thermal annealing. The dependence of the component, orientation, Stress, average grain size and the quality of ZnO nanoparticles on the annealing temperature, ambient and time was studied by X-ray diffraction spectra, surface contour analysis and X-ray photoelectron spectra. The experimental results indicated that the component and orientation of ZnO nanoparticles embedded in Si02 were influenced by the annealing time. The annealing time of 3 hours is not enough to oxidize zinc atom in silica at 5000C. The ZnO nanoparticles without Zn phase embedded in SiO, were prepared at 9000C. During the annealing process, zinc atom diffusion from silica inside to silica surface and zinc atom effusion from silica surfaceoccurred. The density of ZnO nanoparticles embedded in SiO, wasdecreased. The annealing time can control the orientation, average grainsize and stress of ZnO nanopartic1es embedded in SiO, at 700'C. Thezinc ion implantation with high dose and zinc atoms effusion from si1icasurface can give rise to micro-hole, weak bond and breaken bond in silicanear the implantation layer. During the annealing process, the dissppearof micro-hole and the reconstitution of weak and breaken bond will occur.High quality ZnO nanoparticles embedded in SiO, was obtained as theannea1ing time increased to 2 hours at 700'C, We can control the averagegrain size and density of ZnO nanopartic1es by sequentia1 post-thermalannealing zinc-implanted si1ica in nitrogen and...