Novel metallic and semiconductor nanorod/nanowire architectures

本项目的重点是对新型半导体和金属纳米棒结构的详细研究，以便更好地了解其生长过程以及与块体材料在性能上的差异。利用纳米结构衬底可以外延生长单晶半导体纳米棒和周期性纳米棒阵列。自组装胶体颗粒(主要是聚苯乙烯亚微米级单分散球体)的单分子层的形成是公认的，并在各个研究领域得到广泛应用。纳米球光刻(NSL)将用于创建周期性和准周期性自组装球形对象，如直径在200至2000 nm范围内的聚苯乙烯或二氧化硅颗粒。二维和三维(2-D，3-D)有序颗粒将被用作随后沉积不同数量的不同金属的掩模。在蒸发过程之后，将执行面具的升空。金属二维和三维可变颗粒阵列允许控制纳米管之间的距离以及它们的立方体、六边形或更复杂的有序性。在纳米结构的衬底上生长的最终纳米管将通过等离子体增强化学气相沉积来完成。通过掩膜沉积催化剂的量可以决定纳米管的生长厚度，进而直接影响纳米管的光学和电学性质。纳米棒和纳米线的湿化学合成是通过表面活性剂在2-5 nm种子颗粒上的定向聚集/结合或外延生长来完成的。在大多数情况下，所涉及的不断增长的机制仍然未知；对这些不断增长的机制的阐明将是该项目的一个主要重点。正如人们可以预期的那样，不同的材料，如金属和半导体，生长机制不同，我们将研究金属和双金属，以及半导体纳米棒和纳米线。该项目的另一个重点将是调查最终材料的性能。将使用UV/Vis光谱、光学显微镜、原子力显微镜、透射电子显微镜和电子能量损失光谱进行研究。

The focus of this project is a detailed study of novel semiconductor and metallic nanorod architectures in order to gain a better understanding of the growing process and difference in properties to those of the bulk materials. Epitaxially grown single-crystalline semiconductor nanorods and periodic nanorod arrays can be realized by use of nanostructured substrates. The formation of monolayers of self-assembled colloidal particles (mainly polystyrene submicron-sized, monodisperse spheres) is well-established and widely used in various fields of research. Nanosphere lithography (NSL), will be used for the creation of periodic and quasiperiodic self assembly spherical objects like polystyrene or silica particles with a diameter in the range of 200 to 2000 nm. The two and three-dimensional (2-D, 3-D) ordered particles will be used as a mask for the following deposition of various amounts of different metals. After the evaporation process the liftoff of the mask will be performed. The metallic 2-D and 3-D varying particle arrays permit the control of the distance between the nanotubes as well as their cubic, hexagonal or more complicated ordering. The final nanotubes grown on nanostructured substrates will be done by plasma enhanced chemical vapor deposition. The amount of catalyst deposited through the mask can determine the thickness of growing nanotubes with can in turn directly influence their optical and electronic properties. Wet chemical synthesis of nanorods and nanowires has been done by surfactant directed aggregation/coalescence of - or epitaxial growth on 2-5nm seed particles. The growing mechanisms involved are in most cases still unknown; the elucidation of these growing mechanisms will be a major focus of this project. As one can expect that growing mechanisms differ for different materials such as metals and semiconductors, we will investigate metallic- and bimetallic-, as well as semiconducting nanorods and nanowires. A further focus of this project will be the investigation of the properties of the final materials. Investigations will be done applying UV/VIS- spectroscopy, optical microscopy, atomic force microscopy, transmission electron microscopy, and electron energy loss spectroscopy.