Formation mechanism and photoelectric properties of Al2O3 film based on atomic layer deposition

The formation mechanism of metal oxide films is very important to nanomanufacturing and microelectronic devices. We have prepared the aluminum oxide (Al2O3) films with the thicknesses ranging from 1 to 30 nm by using atomic layer deposition technology. By investigating their morphologies and optoelectrical properties, we found that the Al2O3 films grow on substrate via a layer growth mode by atomic force microscope measurement. Grazing incidence small-angle x-ray scattering further proved that a layer structure parallel to the substrate at the thickness of 5 nm. The water contact angle revealed that 5 nm is critical thickness of physical-film formation. The analysis of dielectric characteristics and the performance of thin film transistors revealed that 30 nm is critical thickness of dielectric-film formation. The understanding on structure–function relationships is necessary to realize the potential application of metal oxide films.