掺铝氧化锌薄膜及纳米棒阵列的制备与表征

【作者】 徐迪；

【导师】 段学臣；

【作者基本信息】 中南大学 ， 材料学， 2008， 硕士

【摘要】 ZnO∶Al(ZAO)透明导电薄膜具有优良的光电性能,被认为是ITO薄膜的理想替代品,在平板显示、电磁屏蔽、热阻挡层、气敏传感器、太阳能电池等领域具有广阔的应用前景。同时,ZnO一维纳米结构具有独特的光电性能,在激光、场发射、光电子器件等领域有新的潜在应用前景,因而近年来得到了广泛而深入的研究。但迄今为止还很少有关于水热法合成掺铝氧化锌纳米棒阵列的报道。本文选择合理的实验方法,将ZAO透明导电薄膜和纳米棒阵列这两项研究有机结合起来,展开系统的研究。首先采用溶胶凝胶法,在普通玻璃基片上成功制备出具有完好C轴取向的ZAO薄膜,系统研究了溶胶浓度、Al掺杂量、旋涂次数、预处理温度和退火温度等工艺参数对薄膜微观结构和光电性能的影响。研究结果表明薄膜的光电性能与其晶体取向、表面形貌有密切关系,C轴取向可有效地降低薄膜的电阻率,未经预处理不能获得高度C轴择优取向的薄膜。当掺杂浓度为2at%,预处理温度为300℃,旋涂次数为15次,退火温度为550℃时,薄膜样品在可见光区域的透射率高于80%,方块电阻低至515Ω/□。探讨了薄膜的生长机理,初始阶段的非均匀形核和随后晶核的择优生长促使薄膜择优取向。然后采用低温水热法在修饰了ZAO薄膜的玻璃衬底上制备了窄直径分布、晶体取向高度一致的ZAO纳米棒阵列。研究了各工艺参数对纳米棒形貌、尺寸和性能的影响。研究结果表明:纳米棒阵列垂直于衬底沿[002]方向取向生长,平均直径为50nm左右;表面活性剂PEI具有促进ZAO纳米结构棒状生长的作用;随着铝掺杂量的增加,阵列薄膜的紫外辐射峰发生蓝移,铝掺杂量为2at%的薄膜具有最好的光致发光性能。研究结果表明铝掺杂可以提高ZnO阵列薄膜的发光强度,这为开拓一维ZnO纳米结构在光学领域的应用提供了新的思路。更多还原

【Abstract】 Because of its excellent optical and electrical properties, ZnO:Al(ZAO)thin films are regarded as an alternative transparent conductive material to ITO,which are of interest for a various applications such as displays,window coating,gas sensors and solar cells. Owing to its special photoelectric properties,1D ZnO nanostructures have attracted much research attention for a wide range of applications such as ultraviolet,piezoelectric devices,field emission.But to the best of our knowledge,by far few reports have been made on Al-doped ZnO nanorod arrays by hydrothermal method.In this paper,the research of ZAO thin films and nanorod arrays was combined organically by a reasonable experimental method.ZAO thin films with high preferential c-axis orientation were deposited on glass substrates using sol-gel method.The effects of the processing parameters,including solution concentration,Al doping, preheating and annealing temperature,on the microstructure,electrical and optical properties of the films were investigated.The results showed that the optical and electrical properties of the films were strongly related to the crystallographic orientation and surface morphology of the films. And higher crystal orientation was favorable for reducing the resistivity. The film without preheat treatment exhibited only a small preferential c-axis.The lowest sheet resistivity(515Ω/□)was achieved in the film that contained 2at%of aluminum with 15 layers,using 300℃as the preheating temperature,and 550℃as the annealing temperature.In this case,the transmittance of the film was over 83%with the visible wavelength region.The probable mechanisms underlying the preferential c-axis orientation of the films are the initial orientation due to heterogenous nucleation and the final growth orientation at the film/substrate interface.Well-aligned Al-doped ZnO nanorod arrays with a narrow diameter distribution were successfully grown on glass substrates by hydrothermal method,where the substrates were spin-coated with seed layer.The effects of the processing parameters on the morphology,size and properties were investigated.The results showed as follows:well-aligned ZAO nanorods with an average diameter of 50 nm crystallized along[002] direction were grow vertically on the substrate;the surfactant PEI can promote the rod-like growth of the ZAO nanostructures;with increasing Al doping,the ultraviolet emission of the arrays blue shifted.The best photoluminescence performance appeared when the Al doping is 2at%.The results showed that the Al-doping can enhance the photoluminescence intensity of ZnO nanorod arrays,which provide a new method on the application of 1D ZnO nanostructures in the optical field.更多还原