Ponente
Descripción
Among transparent conducting oxides (TCOs), ZnO has become one of the most important materials in optoelectronic last years. This is related to its unique properties, allowing a wide and increasing range of applications, such as light emitting diodes, semiconductor lasers, transparent electrodes for panel displays, solar cells and resistive sensors of harmful gases. The last two applications are relevant in view of the urgency of solving the increasing necessity of energy and stopping the growing deterioration of the environment. Moreover, this material can be obtained through simple, low cost and suitable for mass production processes, such as spray pyrolysis, making this material competitive regarding ITO (indium-tin oxide), the classical and so far most used TCO. Previously we reported on the characterization of sprayed ZnO thin films deposited on grass substrates by using a classical homemade spray set up and zinc nitrate as starting precursor. ZnO layers with stable and repetitive properties were obtained. However, low magnification SEM images exhibited a pattern of circular spots, as formed by impact of the spray droplet on the hot substrate. It is indicative of liquid-solid reactions during film deposition, thus providing inadequate film properties for most optoelectronic applications. In the present work we report on the development of a new set up, based on an ultrasonic nozzle. Almost transparent, nanostructured, with stable and repetitive properties ZnO layers were deposited on glass and c-Si substrates from zinc acetate solution. Preliminary results, as obtained through SEM, optical transmittance and photoluminescence spectra measurements are described here.
