Research On Controllable Preparation And Optical Properties Of ZnO Quantum Dots On Nanobelts

In this paper,ZnO/CuO hetero-structures and ZnO/SnO2 hetero-structures were synthesized by thermal evaporation. The catalyst was characterized by scanning electron microscopy(SEM), powder X-ray diffraction(XRD), transmission electron microscopy(TEM), and energy disperse spectroscopy(EDS). The structure and optical properties of materials were obtained via Ramam scattering and photo-luminescence(PL) spectroscopy. Besides, such as the conditions of ZnO quantum dots growth on CuO Nanobelt, the morphology control of CuO nanobelt, the growth mechanism of SnO2 Nanowire and ZnO quantum dots growth mechanismon SnO2 nanowire were also studied in this paper.1. ZnO/CuO nanobelts hetero-structure controlled synthesis and their optical propertiesFirst, CuO nanobelts were fabricated by thermal evaporation, and the best growth conditions were found. Subsequently, the CuO nanobelt were soaked into the solution of zinc acetate, which formed a thin film on the CuO nanobelt and annealed under certain conditions. The best growth condition,which are very beneficial to controll growth of ZnO quantum dots on CuO nanobelt is annealing at 450℃ for 3h in an Air atmosphere, among them, the gas flow of Ar is 200 sccm. TEM and XRD analysis results reveal that quantum dots uniformly distributed on the CuO nanobelt with an average thickness of 5-10 nm. Ramam spectrum show that there are peak shift at 297.6,345.7,and 630.5cm-1. Among them, the Raman peak at 297cm-1 is the characteristic peak of crystalline CuO, which is corresponding to A2/B2 vibration mode. The Raman peak at 345.7cm-1is the correspongding A1/E1 longitudinal mode of Zinc Oxide. The Roman vibration mold at 630.5cm-1 is the correspongding IR-activemodes.2. The praperation of ZnO/SnO2 nanobelts hetero-structure by thermal evaporation and their optical propertiesZnO/SnO2 nanobelts hetero-structure were synthesized via a two-steps method.The first step, SnO2 nanobelts hetero-structure were prepared by thermal evaporation.Subsequently, the SnO2 nanobelts were soaked into the solution of zinc acetate and then annealing in the tube furnace. The optical properties of pure SnO2 nanobelts and ZnO/SnO2 hetero-structure were studied by PL and Ramam, which show that the pureSnO2 nanobelts has two convolution sub band at 613 nm and 727 nm. The PL spectra of SnO2/ZnO hetero-structures reveal that two convolutions sub band are located at636.6nm and 840.8nm by Gaussian fitting. The phenomenon of red-shift is due to ZnO quantum dots which changeed the bandgap of SnO2.