ZnO nanostructures: Growth processes, structure, resulting properties and applications
Monica Tirado, S Real, N Vega, E Tosi, P Gallay, P Alastuey, O Espindola, O Marin, G Grinblat and D Comedi
Universidad Nacional de TucumÃÂ¡n, Argentina
: J Nanomater Mol Nanotechnol
The use of low dimensional structures is a key technological factor in the creation of new functional and sensing devices which benefit from their large surface area to volume ratio. Also, many properties of nanomaterials depend not only on their size but also on their surface state. The properties of nanosized semiconductors are largely determined by surface effects and hence much effort has been directed recently to study and engineer these effects. One of the strategies has been the quest for a proper understanding and control of the relation between nanostructure growth processes, structure, and resulting properties. Among the semiconductors materials, the ZnO is considered an important and promising material. Reasons for this include low-cost, simple and controllable synthesis processes of a wide diversity of nanostructures, such as nanoparticles, nanowires, nanocones, nanostructured films. ZnO nanostructures are subject of increasing interest due to their interesting potential applications in photonics, and chemical and biological sensing. These motives led our research group to develop different techniques for the manufacture of ZnO nanostructures. The production of nanoparticles (precipitation methods), thin films (sol-gel) and nanowires, nanocones (steam technique or electrophoretic deposition) will be detailed. We will also explain the efforts we are making to understand and control the surface processes that mainly affect two aspects: 1) recombination of electrons and holes, and therefore the optical emission and 2) the electrochemical processes. These studies are very important for applications in luminescent emitters (LEDs, lasers) and in the development of amperometric biosensors based on ZnO nanowires or ZnO thin films. Finally, we will discuss photoluminescence, impedance spectroscopy and electroluminescence or electrochemistry in structures and devices of ZnO/MgO, ZnO/PEDOT, and ZnO/GOx (glucose oxidase) nanostructures.