论文标题:金属/AAO纳米有序阵列复合结构的光学特性研究
Ordered Metal/AAO Nano-array Composite Structure and Their Optical Properties
论文作者 李燕
论文导师 王成伟,论文学位 硕士,论文专业 凝聚态物理
论文单位 西北师范大学,点击次数 147,论文页数 85页File Size4714k
2004-05-01论文网 http://www.lw23.com/lunwen_69701957/ 高度有序纳米阵列复合结构,光学特性,调制,多孔阳极氧化铝模板,电化学沉积
high ordered nano-array composite,optical properties,modulation,porous anodic aluminum oxide membrane,electrochemical deposition
本论文首先简要综述了国内外关于纳米结构的研究现状，并评述了当前模板法合成纳米有序阵列结构的工艺与物性研究方面的一些最新进展。接着论文全面总结了作者近几年以金属／AAO纳米有序阵列复合结构光学特性为选题的研究工作：进一步优化了制备金属／AAO纳米有序阵列复合结构的工艺参数，较系统地考察了分别由几种不同金属(Co、Ni、Ag、Cu)植入AAO模板后，合成的纳米有序阵列复合结构样品的光反射、透射和吸收等一般光学特性，还专门研究了各系列结构样品吸收边的频移、金属纳米粒子表面等离子激元共振吸收特性，以及特殊的半导体光学特性等。进而发现了这类复合结构独特的光学性质与制备工艺参数群之间有趣的相关性，并较深入地探讨了二者所遵循的内在规律。文中主要述及了以下几方面的研究结果： 1．调整制备多孔阳极氧化铝(AAO)模板的电化学工艺参数群(如电解质的种类及浓度、阳极电压及电流、温度、时间等)，可使AAO模板内的微孔分布高度有序且其结构参数，如孔的密度(10~8～10~(11)cm~(-2))、直径(10～200nm)和深度(500nm～100μm)，在很大范围内可控； 2．金属／AAO纳米有序阵列复合结构的金属组分含量、纳米粒子的长径比、纳米粒子的间距和分布密度等重要结构参数，都可以通过选用不同的AAO模板和改变电化学液相沉积工艺参数(如电压、频率、时间、浓度及pH值等)加以调控； 3．研究了Co／AAO纳米有序阵列复合结构的光学特性，结果表明，Co／AAO复合结构在可见至近红外波段不仅具有高且基本恒定的透射率，而且具有均一的光反射率。随体系中Co沉积量的增加，Co／AAO复合结构的吸收边将发生较大幅度的红移(观察到的频移量约为80nm)，而光反射率随之降低(调制幅度可从70％至6％)，且反射特性更加敏感于Co纳米线直径的变化； 4．实验比较研究发现，相同工艺条件下制备的Co／AAO和Ni／AAO纳米有序阵列复合结构，其光学特性却出现较大差异，二者虽然在可见至近红外波段均具有高且基本恒定的光透过率，但其光吸收特性却不尽相同，随着金属(C。或NO组份比的增加，Ni/AAO吸收边的红移量仅约13nln，而co/AAO的吸收边红移量却超过了80lun，分析发现Ni/AAO复合体系具有间接带隙半导体的光学特征，而CO从AO复合结构则具有直接带隙半导体的光学特征; 5.实验研究了A创AAO纳米有序阵列复合结构的光吸收特性，在其光吸收谱上出现了较强的Ag表面等离子体振荡吸收峰，随Ag沉积量的减少，吸收峰位发生红移，且逐渐展宽.用M一G有效介质理论计算模拟了A幼认O纳米有序阵列复合结构的共振吸收特性，其定性结果与实验规律完全一致，解释了化的主要原因;复合结构吸收峰位频移及宽6.制备并测试了系列纳米有序阵列复合结构的光吸收特性，实验发现了随Cu沉积量的增加，C可AAO的吸收边出现从近紫外至近红外的大幅度红移，并将随之稍有蓝移的Cu表面等离子共振吸收峰逐渐掩盖而使其消失的新的现象.实验观察到Cu表面等离子体共振吸收峰位在570lun附近的吸收边频移量超过了500 nln.理论分析表明，吸收峰位的移动主要源于偶极共振，而峰形的宽化主要由纳米粒子的表面效应和量子尺寸效应引起.
Recently, anodic aluminum oxide (AAO) membranes with a regular porous structure have been prepared by electrochemical methods and have widely been used to produce various nanostructured materials within highly ordered channels in the AAO membrane in which the diameters and lengths of the inserted nanowire can be well controlled. In this dissertation, after reviewing the latest development in research of the novel system of nano-array composite by using template method, reports my research work of fabricating metal/AAO nano-array composite and their novel optical properties in the past few years. Different metal/AAO composites ranging in volume fraction of the metal showed unusual size-dependent optical properties, some important results obtained are as following:1. Porous AAO are prepared by anodization of Al sheets in sulfuric, phosphoric and oxalic acid aqueous solutions. We have optimized the set of parameters, which make pore arrays in AAO membrane highly ordered. Changing the conditions of oxidizing, we obtained series of pore arrays with controlled structures, such as diameter (from 10 to 200 nm), depth (from 500 nm to 100 nm), and density (from 108 to 1011 cm-2).2. Series of aligned metal nano-arrays with controlled diameters, length, volume fractions and density are obtained by electrodepositing the metal in the corresponding AAO membranes which have the same structure parameters, or adopting different depositing conditions, such as voltage, time and pH.3. Ordered Co nano-arrays have been prepared via electrodeposition of the metal within the nanoporous AAO template. Measurements show that the optical properties of the Co/AAO composites depend on the length and the diameters of Co nano-wires. As the Co composition increased, the absorption band-edge is strongly red-shifted (115 nm) and the even reflectance of the composite change from 70 % to 6 %. Meanwhile the reflectance is more sensitive to the change of the diameter of Co nano-wire.4. We have fabricated Co/AAO and Ni/AAO nano-array composites in same conditions, and studied the optical properties of the two composite. The results show that the differences between the two composites are very large. Although the micrograph of the Ni nano-wire andthe Co nano-wire are nearly the same, as the metal composition increased, the absorption band-edge of the Ni/AAO composite is small red-shifted (13 run), however, the absorption band-edge of the Co/AAO composite is strongly red-shifted (80 nm). Meanwhile, the Ni/AAO and Co/AAO composite exhibit the optical features of the semiconductor with indirect and direct band gap respectively.5. Studied the plasma resonance absorption properties of the Ag/AAO nano-array composite. The spectral analysis shows that the surface plasmon resonance peak of Ag occurs at X =352 ~ 377 nm. As the Ag composition decreased, the dipolar plasma resonance absorption peak shifted to a longer wavelength, strengthened and gradually expanded. AAO membranes have small effect to the location of the absorption peak. The theoretical analysis shows the M-G calculated results are agreed well with the experimental ones.6. We have investigated the effect of Cu composition on the absorption properties of Cu/AAO nano-array composite in the wavelength range 200-1000 nm. The absorption characteristics was that the surface plasma absorption peak appeared around 570 nm shifted to a short wavelength and strengthened as the Cu composition increased. But the maximal shift range of the absorption-edge preponderated over 500 nm, and leaded that the dipolar plasma resonance absorption peak were covered up and gradually disappeared in the absorption spectrum. We theoretically explained the mechanism of the modulating action.
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