Spray pyrolytic deposition of transparent aluminum oxide (Al2O3) films

Optically transparent Al2O3 films has been synthesized, on quartz substrates at 500, 600 and 700 °C, from 0.02 M aluminum acetyl acetonate (Al(acac)3) in ethanol, by using ultrasonic spray pyrolysis technique. The films synthesized at 500, 600 and 700 °C are amorphous having average particle sizes 27 ± 6, 18 ± 3 and 14 ± 3, respectively. The films are found to be 95% optically transparent in the visible region. The optical transparency of the films in the ultraviolet region is found to increase with increase in deposition temperature. The observed increase in optical band gap and decrease in refractive index is attributed to the decrease in particle size with increase in deposition temperature. The stoichiometry and chemical bonding of the amorphous film studied using XPS and FTIR spectroscopy revealed the presence chemisorbed oxygen.

► Transparent thin films of alumina were synthesized by ultrasonic spray pyrolysis. ► The refractive index, film thickness and band gap were measured by ellipsometry and UV-vis spectroscopy. ► The compositional analysis and chemical bonding in the films were done using X-ray photoelectron and FTIR spectroscopy.