There are two basic approaches of synthesizing nanowires: top-down and bottom-up pproach. In a top-down approach a large piece of material is cut down to small pieces hrough different means such as lithography and electrophoresis. In a bottom-up approach he nanowire is synthesized by the combination of constituent ad-atoms. Most of the ynthesis techniques nowadays are based on bottom-up approaches. | 10 Doping of Polymers with ZnO Nanostructures for Optoelectronic and Sensor Applications Aga and Mu Fisk University USA 1. Introduction The discovery of new materials with unique properties often leads to new technology. After discovery of conductive polymers at the end of the 1970s it opened up a whole new research which eventually led to a new technology of plastic electronics Chiang et al. 1978 . When interesting material properties are observed in the laboratory efforts are made to understand their mechanisms which leads to the fine control of the fabrication process of this new and potentially important material. If future applications are anticipated optimization of material properties becomes a continuous and sometimes a lifelong process. Doping of materials is one of the ways of modifying their physical properties. For example a pure silicon Si which has a very poor electrical conducting properties can be doped with boron or arsenic to make it a good hole or electron conductor respectively. This opened up a new class of doped-Si materials which is now the basis of perhaps the largest global electronics industry. Polymers which consist of large molecules linked together in repeated fashion to form long chains have naturally existed for a long time. Examples are tortoise shell tar and horns. Today synthetic polymers are finding important applications in many areas. Polyolefins epoxies and engineering resins are crucial materials for construction commerce transportation and entertainment. They are very appealing alternative materials because of the simple processing they offer such as drop casting spray painting and printing. In addition they almost provide low cost large-area scalability. In most applications however polymeric materials are multicomponent systems. The integration of fillers such as minerals ceramics metals or even air can generate an infinite variety of new materials with unique physical properties and possibly reduced production cost. .
