Al（NO₃）₃ Catalysis Fabrication And Characterization Of Nano ZnO By CVD On Si Substrate

ZnO as important member ofⅡ-Ⅵwide band gap compound semiconductormaterial which has semiconductor, piezoelectric and pyroelectricity prosperities,commonly used in area of optical device, photo electronics, sensor and brake. Recentyears, various and novel nanostructures of ZnO was prepared by researcher, includingnanowires, nanotubes, nanobelts, nanocombs and nanorings, have been fabricated bydifferent methods, such as wet-chemical method, electrochemical deposition,templating method, molecular beam epitaxy method, radio-frequency magnetronsputtering deposition and metal-organic chemical vapor deposition.Our group had fabricated the long tail diode-shape ZnO nanostructures, the shorttail diode-shape ZnO structures and multipod ZnO nanostructures with simple andefficient method. The X-ray diffraction （XRD）, Scan electron microscope （SEM）,Transmission electron microscope （TEM）, High resolution transmission electronmicroscope （HRTEM）, Photoluminescence （PL） and X-ray photoelectron spectroscopy（XPS） were used to analyse the structure, morphology, luminescent properties andchemical composition. Preliminary discussion the special function of the polar faceorientation growth in the formation process and the growth mechanism was researched.1. The long tail diode-shaped ZnO nanostructures and the short tail diode-shaped ZnO structuresThe long tail diode-shaped ZnO nanostructures and the short tail diode-shaped ZnOstructures were prepared at different reaction time on the Si （111） substrate which wascoated by concentration of 10% aluminum nitrate in ethanol solution use CVD method at 1050℃. In the react process, the Al（NO₃）₃decompose into Al2O3cover on thesubstrate which provide nucleation sites and promote the growth of crystal and play therole of catalyst. The long tail diode-shaped ZnO nanostructures and the short taildiode-shaped ZnO structures which have smooth surface, high quantity and highcrystallinity were fabricated by adjust the temperature, time, gas flow. The long taildiode-shaped ZnO nanostructures were studied by XRD and TEM. The result indicatethat the nanostructures are single crystal wurtzite structure and the growth direction is[0001]. EDS analysis shows that the sample atomic ratio of Zn and O is about 1. Roomtemperature photoluminescence spectra （PL） shows the diode-shaped ZnOnanostructures exist UV emission peak and green emission peak, peak centers arelocated at 384nm and 540nm. The light-emission mechanism is analysised. The XRD,SEM, HRTEM, SAED and EDS were used to research the structure, morphology andcomposition of short tail diode-shaped ZnO structures.The results indicate that the shorttail diode-shaped ZnO structures also have high crystallinity and the structure is ZnOhexagonal wurizite structure. At last, the formation mechanism of diode-shaped ZnOnanostructures is discussed. This novel ZnO nanostructures have a greater significantfor study on performance and application of novel ZnO nanostructures.2. The multipod ZnO nanostructuresThe multipod ZnO nanostructures were prepared on the Si （111） substrate which wascoated by concentration of 10% aluminum nitrate in ethanol solution use CVD method.Under the condition of Al（NO₃）₃decompose into Al2O3layer on the substrate form somedefects which supply nucleation point for the multipod ZnO nanostructures. Usecarbothermal reduction chemical vapor deposition method and adjust the temperature,time, gas flow to preparation the multipod ZnO nanostructure. The morphology ofsample was researched by SEM. The multipod ZnO nanostructures have smooth surface.The XRD and TEM study indicate that the whole nanostructure is monocrystal and thegrowth direction is perpendicular to the （0110）. Each leg’s diameter is became more andmore small from the base to the tip and radial growth. The XPS result of the multipodZnO nanostructure shows the sample only contain Zn and O no other impurities.