High quality-low temperature aluminum oxide films deposited by ultrasonic spray pyrolysis

High quality aluminum oxide thin films have been prepared at relatively low substrate temperatures using aluminum acetylacetonate as source material. The structural properties were analyzed by ellipsometry and infrared spectroscopy. The electrical integrity was analyzed by I–V and C–V measurements performed in metal/oxide/semiconductor structures where the deposited oxides were incorporated. Good quality aluminum oxide films were obtained at substrate temperatures as low as 350 °C. The deposition rate has relatively high values from 7.0 to 11.4 nm/min. The refractive index takes values around 1.645, which is of the order of those obtained using vacuum processes. Destructive breakdown electric field is higher than 6 MV/cm. The capture cross section per unit area (9.3×10^-15cm²) is associated with trapping centers with coulombic potential. From quasistatic and high frequency C–V measurements, a density of interface states at midgap of 1.6×10¹¹ (eVcm²)^-1 was calculated.