Fabrication Of ZnO thin film and nanostructures for optoelectronic device applications

Abstract

Zinc oxide, as one of the promising semiconductor materials, has attracted considerable attention in optoelectronic applications due to its promising properties, including a wide band gap of 3.37 eV at room temperature, a large excitation binding energy of 60 meV, high chemical stability, and transparency. Recently, one-dimensional ZnO nanostructures have been extensive investigated due to their potential application for nanodevices such as solar cells, lighting, chemical sensors, and electrical devices and a variety of display units. In this chapter, we introduce the most convenient method to deposit reproducible and homogeneous ZnO thin films over a large-area substrate at a lower deposition temperature. The critical parameters which will influence on the property of ZnO thin film are investigated. It is found that the gas ratio (Ar/O2) and deposition pressure significantly influence the structural and optical properties of ZnO film. In order to apply the ZnO nanostructures to the photovoltaic device, we also developed a novel method to fabricate well-aligned ZnO nanostructures from as-deposited ZnO thin film by thermal annealing method. The substrate dependence and growth mechanism are analyzed. Moreover, a novel mist chemical vapor deposition method is introduced for the first time to modify the obtained ZnO nanostructures. The morphology of ZnO nanostructures could be controlled well by adjusting the deposition time and carrier gas. This work provides a much useful technique to fabricate high quality ZnO thin film and nanostructures which can be expected to apply in thin film transistor, sensor, dye-sensitized solar cell industries in the near future.