Study on band gap and dispersion model of Al2O3 thin films with different oxygen flow rates by ion beam sputtering

Six groups of single-layer Alumina (Al₂O₃) thin films with different oxygen flow rate were prepared by ion beam sputtering. The oxygen flow rate changed from 0 sccm to 50 sccm with the interval of 10 sccm. The transmission spectrum, reflection spectrum and ellipsometric reflection spectrum of Al₂O₃ thin films were analyzed by cody-lorentz model inversion calculation. The surface roughness of six groups of samples was measured by white light interferometer. The effects of oxygen flow on band gap, Urbach band-tail absorption, deposition rate, surface roughness, deposition rate of Al₂O₃ thin films were studied. The experimental results showed that oxygen flow directly affects the band gap, Urbach tail absorption, deposition rate, surface roughness and deposition rate of Al₂O₃ thin films.