Aluminum oxide thin films deposited on silicon substrates from Al(NO ₃)₃ and an organic solvent by spray pyrolysis

Aluminum oxide thin films were deposited on silicon substrates at temperatures in the range from 500 to 650 °C, from Al(NO₃) ₃ dissolved in N,N-Dimethylformamide and using the spray pyrolysis technique. The films of aluminum oxide resulted stoichiometric, amorphous and optically transparent in the visible spectrum, with a refractive index close to 1.66 when a 0.2 molar solution of Al(NO₃)₃ was used. The films as deposited had a surface roughness as low as 3.8 nm and were almost free of Al-OH bonds, depending on the experimental deposition conditions. The best films were incorporated in a Metal-Oxide-Semiconductor structure and were able to stand electric fields up to 2 MV/cm without destructive break-down and a dielectric constant of 7.95.