| Zinc oxide (ZnO), due to its direct wide electron energy bandgap of3.37eV and large exciton binding energy of60meV at room temperature (RT), has caused great concern in material field for its excellent photoelectricity performance and abundant nanostructures. Besides, ZnO nano-semiconductor material is considered to have potential application in photoelectron, solar cells, sensors and bio-devices. So far, doping and morphology controlling have been two mainly means in improving performance of materials. As for ZnO, although the efforts about these respects have been made great advances, there are still many problems to be solved, such as P-doping ZnO and morphology tailor based on application in devices.In this paper, ZnO-based nanomaterials are the main research object. In the condition of effective combination of doping and morphology tailor, highly-transparent Al-doped ZnO porous network thin films have been prepared by sol-gel and low-temperature hydrothermal methods. Then on this basis, we fabricated Co doped ZnO textured thin films. Finally, one dimensional (1D) and heavily doped Zn1-xCoxO six-prism nanorods have also been successfully synthesized. Morphology, structural, optical and magnetic properties of ZnO-based nanomaterials have been investigated. Besides, the influence of growth temperature, time, the content of sodium hydroxide (NaOH) and the dopant on these properties has been discussed. During this process, we characterized ZnO-based samples by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Photoluminescence spectrum (PL), UV-vis spectrophotometer, vibrating specimen magnetometer (VSM), and discussed optical, magnetic and related machenism. The main contents of this paper could be summarized as follows:1. Highly-transparent Al-doped ZnO (ZAO) porous network thin films are prepared via sol-gel and solvothermal method for the first time. It is found that the morphology of the nanostructures evolved from nanosheets to porous network structures because of the different annealing temperature, time and the content of NaOH in the solution. The incorporation of Al and the contents of NaOH play important roles in the morphology of porous network nanostructures. A growth mechanism is proposed to explain these findings. Al is successfully doped into the ZnO wurtzite lattice structure as revealed by X-ray diffraction (XRD) and verified by the energy dispersive X-ray detector (EDX). The unique nanostructure thin films exhibit a typical wurtzite structure and strong violet emission. Ultraviolet-visible spectroscopy (UV-vis) shows the films have a good transparency, and the absorption edges are obviously blue shifted with a temperature increase.2. Depending on the ZnO seed-layers, a new kind of cobalt doped zinc oxide (Zn1-xCoxO) thin films with controllable morphology were prepared by a facile solvothermal method. A series of ZnO thin films with different Co contents were applied to study the effect of doped Co on morphology, structural and optical properties. It is found that the doped content plays an important role on morphology evolution of Zn1-xCoxO films. The results of scanning electron microscope (SEM) indicate that the Zn1-xCoxO films are highly uniform and porous. Co has been successfully doped into the ZnO lattice structure and revealed by X-ray diffraction (XRD) and energy dispersive spectrum (EDS). It can be found that Zn1-xCoxO thin films possess good crystalline quality through the characterization of transmission electron microscope (TEM) and high-resolution transmission electron microscopy (HRTEM). All of the samples show a stronger violet emission and ultraviolet absorption, and the violet emission peaks shift towards red with increasing of Co content. In addition, the magnetic result demonstrates that the prepared Co-doped ZnO thin films are room-temperature ferromagnetic materials.3. One-dimensional (1D) and heavily doped Zn1-xCoxO (x=0.05,0.1,0.15and0.2) nanorods (NRs) were successfully fabricated by a new solvothermal method. Such a Zn1-xCoxO nanorod exhibits a hexagonal prism-like microcrystal with a pyramidal top. Analyses from transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) indicated that Zn1-xCoxO NRs possess perfect single crystal wurtzite structures. The influence of Co doping on the structural, optical and magnetic properties of NRs was investigated in detail. It was verified that Co was successfully doped into the ZnO wurtzite lattice structure by X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS), and the result of X-ray photoelectron spectroscopy (XPS) also supports this affirmation. The Zn1-xCoxO NRs show an obvious blue-green emission except for the weak UV emission. The corresponding luminescence mechanism was discussed, and the environment of cobalt in the ZnO wurtzite lattice was also identified through UV-vis spectroscopy. In addition, the magnetic hysteresis (M-H) curves demonstrated that the Zn1-xCoxO NRs possess obvious ferromagnetic characteristics at room temperature. |
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