Morphology of nanometric size particulate aluminium-doped zinc oxide films

Aluminium-doped zinc oxide films were prepared through an alcoholic sol–gel route using Zn(CH3COO)2 · 2H2O as non-alcoxide precursor. Al(NO3)3 · 9H2O was used as dopant with an aluminium to zinc ratio of 5% (mol). Lactic acid was used as the hydrolysis promoter. Acetylacetone and diethanolamine were used as additives to improve film homogeneity. The dip-coating process was used for the sol transfer. The chemical processes that occur during thermal decomposition of the precursors were followed by Fourier transform infrared spectroscopy. It is observed that the ZnO stretching (400 cm−1) appears after treatment at 200 °C as the intensity of the asymmetric and symmetric carboxylate peaks (1580 and 1430 cm−1) decrease. Evidence for the presence of aluminium was obtained by energy-dispersive X-rays analysis. Atomic force micrographs of the films were obtained in the non-contact mode and it was shown that the additives as well as the firing temperature of the transferred sols change the particle size of the oxide films, but the morphology is not affected by the alteration of these conditions. In both cases, the particles have average size in the range of 50–60 nm. Film crystallinity is increased with temperature.