Electrolytic synthesis of Al-doped ZnO nanopowders with low electrical resistivity

Al-doped ZnO (AZO) nanopowders with different Al content were fabricated by a galvanostatic electrolytic method. The electrical resistivities were measured by a cell method, which reached its minimum (28 Ω.cm) at 0.93 at.% of Al with its grain size of ̃30 nm. Microstructures of powders were characterized by X-ray diffraction and transmission electron microscopy (TEM), which showed a decrease in grain size with the increase of Al content. In addition, the distributions of Al and the chemical bonding nature of Al atoms were examined by STEM-EDS and by X-ray photoelectron spectra, respectively, which suggested the substituational incorporation of Al atom into the ZnO lattice. Absorption properties were investigated for wavelength ranging from 250 to 2500 nm, which showed that the film coated with AZO nanopowders exhibited a rapid decrease in transmittance below 370 nm to ̃0% and beyond 1250 nm to ̃40% (at 2000 nm).