Synthesis and Growth of ZnO Nanowires

One dimensional nanostructures are useful materials for investigating the dependence of electrical and thermal transport or mechanical properties on dimensionality and size reduction (or quantum confinement). These materials are expected to play an important role as both interconnects and functional units in fabricating electronic, optoelectronic, electrochemical and electromechanical nanodevices. Nanowire-like structures are the ideal system for studying the transport process in one-dimensionally (1D) confined objects, which are of benefit not only for understanding the fundamental phenomena in low dimensional systems, but also for developing new generation nanodevices with high performance. ZnO is one of the most fascinating material that has a diverse group of growth morphologies, such as nanocombs, nanorings, nanohelixes/nanosprings, nanobelts, nanowires, nanocages etc. As with any semiconductor, 1-D ZnO nanostructures provide an attractive candidate system for fundamental quantization and low-dimensional transport studies. The large surface area of the nanorods and bio-safe characteristics of ZnO makes them attractive for gas and chemical sensing and biomedical applications, and the ability to control their nucleation sites makes them candidates for micro-lasers or memory arrays. The ability to control the synthesis of high quality ZnO nanowires leads to potential applications in UV photodetection, gas sensing, light-emitting nanodevices and transparent electronics. Therefore the controlled and large scale synthesis of these one dimensional nanomaterials are of potential importance. Various methods as thermal evaporation, wet chemical, laser ablation, hydrothermal etc have been widely imployed for the growth of ZnO nanostructures. This review represents the review of current research activities on the synthesis of ZnO nanorods (or nanowires) and the various growth process and mechanism have been discussed. Some possible application of these nanomaterials are also discribed.