Electrophoresis Deposition of ZnO Nanoestructures: Au Nano-clusters on the Substrates Induce Nanowire Growth

REAL, SILVINA; SANDOVAL, CLAUDIA; MARIN, OSCAR; COMEDI, DAVID; TIRADO, MONICA

Hernstein

Conferencia; International Conference on Electrophoretic Deposition V: Fundamental and Applications (EPD 2014); 2014

The American Ceramic Society

The present work reports the growth of ZnO nanowires on silicon substrate with nanometer sized Au clusters using electrophoresis deposition technique at room temperature.The ZnO nanostructures were grown from a low concentration of ZnO nanoparticles colloidal suspension in 2-propanol. The size of the nanoparticles obtained in the colloidal suspension was estimated from absorbance and photoluminescence measurements, which yielded an average diameter of 5 nm with a narrow size distribution, between 4 and 7 nm. The gap energy of synthetized nanoparticles was 3.47 eV. Chemical properties of the resultant colloidal suspension were measured: conductivity, pH, zeta potential, density and viscosity in order to calculate relevant parameters in EPD like electrophoresis mobility.In order to find the best way to obtain homogeneous and reproducible deposits, a careful design of the cell was performed. This allowed the engineering of the directionality and intensity of the applied electric field, which is one of the main parameters determining the effectiveness of the EPD method in producing complex nanostructures with controlled thickness and morphology. The effects of the electric field intensity and distribution on the properties of the nanostructures obtained were studied and discussed. Also, the effect of other process parameters, such as deposition time and adding zinc nitrate to colloidal suspensions at two different concentration 5% and 20 %, were analyzed.The substrates used were commercial Si wafer, and Si wafer covered with Au nano-clusters deposited by sputtering. To determine the quality of the ZnO nanostructures obtained by EPD, measurements of scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy and photoluminescence were performed The results show that the deposition of Au nano-clusters on the silicon substrate induces a vertical alignment of the ZnO nanoparticles which allows the formation of nanowires without the use of templates (see Fig.1). This particular growth is probably due to increased electric field intensity near the Au nano-cluster.The growth of semiconductors nanowires at room temperature is of a great industrial interest because it minimizes the production costs compared with conventional techniques and enables the growth on substrates that cannot withstand high temperatures, such as polymers.