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模板辅助下氧化锌微纳结构的生长研究
Templates Assisted Preparation of ZnO Micro/Nanostructures
【作者】 陶颖镭;
【导师】 王永生;
【作者基本信息】 北京交通大学 , 凝聚态物理, 2010, 硕士
【摘要】 利用模板辅助对ZnO微纳结构的大小、形貌、结构和排布等进行控制,在ZnO微纳器件制备及应用方面具有重要意义。在本文中,我们首先采用低温液相水热法,在预修饰了磁控溅射制备的籽晶层的衬底上,成功制备了大密度且高度取向的ZnO纳米棒阵列,首次对籽晶层制备时的磁控溅射参数对ZnO纳米棒形貌的影响进行了探讨。通过调节前驱体溶液浓度、加入柠檬酸钠或聚乙醇胺,制得了不同形貌、不同长径比的取向ZnO纳米棒/塔/线阵列。在此基础上,通过在籽晶层上覆盖光刻胶层做为模板, ZnO微纳结构的在衬底上的空间分布控制得以实现,在调整生长参数后,得到了周期性排列的ZnO纳米棒/管/线/环状阵列。更为重要的是,通过将生长过程分为两步,并使用柠檬酸钠和聚乙醇胺这两种作用相反的辅助剂,在光刻胶模板微孔的限制下实现了籽晶层多晶晶种的融合,首次在多晶衬底上以传统光刻技术精确控制了单个ZnO晶体的生长位置,并将控制单个ZnO棒晶的模板尺寸由文献普遍报道的100nm左右拓展至微米量级。提出了模板限制与辅助剂修饰双重作用下的生长机理,在模板微孔的作用下,相同水热生长条件下制得的纳米柱增粗至了光刻胶微孔粗细,制备的一维棒晶的直径和长度均可控制。最后,通过使用自组装聚苯乙烯胶体晶体做模板,我们发展了一种采用磁控溅射技术制备面积达到厘米尺寸的ZnO纳米碗阵列薄膜的方法。通过改变聚苯乙烯微球直径及磁控溅射时间,制备的纳米碗尺寸及纳米碗阵列薄膜的厚度均可调整。
【Abstract】 Using templates to control the size, morphology, structure and arrangement of ZnO micro-nano structures is of great significance in preparations and applications of ZnO micro/nano-devices.In this thesis, we synthesized well-aligned ZnO nanorod arrays by hydrothermal method on Si substrates that were covered with pre-deposited ZnO films as seed layers. The ZnO seed layers were deposited by RF magnetron sputtering. We explored the effect of sputtering parameters of seed layers such as oxygen partial pressure and annealing on the morphology of ZnO nanorod arrays. To the very best of our knowledge, these works have seldom been done before. By adjusting the precursor concentration, or adding different capping agents like sodium citrate and polyethylenimine(PEI), aliened ZnO nanrod/towe/wire arrays with different morphologies and aspect ratios were successfully synthesized.Besides, by patterning photoresist layer on the surface of seed layers via conventional lithography, a simple aqueous solution route was demonstrated to control the growth positions of ZnO micro/nanno-structure arrays on the substrates. Through adjusting the growth parameters, periodic ZnO nanorod/tubes/wire/circular arrays were prepared with the assist of photoresist templates.Furthermore, under the functions of capping agents like citrate and polyethylenimine (PEI), two kinds of organic molecules that could hinder the axial and lateral growth of the nanorod and separating the growth process into two steps, multi grains within one photoresist hole fused together into single crystal with restriction of photoresist template. For the first time, it is possible to define the position of single oriented one dimensional ZnO crystal on polycrystalline substrates instead of expensive single crystal substrates at low temperatures and large scale. The size of template to control the growth position of single ZnO nanorods has been extended from 100nm that literature generally reported to the range of micrometer. A crystal growth mechanism was proposed when growing under the functions of photoresist templates and capping agents.With restriction of photoresist templates, the diameters of nanorods were enlarged to the size of photoresist holes under the same hydrothermal growth conditions, the prepared ZnO one dementional structures have controlled diameters and lengths.At last, ordered ZnO nanobowl arrays over cm2 areas were prepared by magnetron sputtering using the self-assembled colloidal crystals as templates. The process started with self-assembled sedimentation of there-dimensional (3D) hexagonal polystyrene sphere arrays. By depositing ZnO within the interstitials of 3D colloidal crystal templates using magnetron sputtering, large-area ordered ZnO nanobowl sheets were prepared after removing the spheres by annealing. The whole nanobowl sheet could be lifted off, leaving accidentally observed inverse opal structures. The sizes of the nanobowls could be controlled by the size of the polystyrene spheres, the height of nanobowl sheets could be altered by changing sputtering parameters.