Al/Al2O3 film growth and laser-induced transformation

The cermet, Al/Al2O3 deposited on clean Si(1 0 0), was investigated for the mechanism of its transformation induced by laser irradiation. The films were deposited by reactive sputter deposition and, subsequently, irradiated with a single 1064 nm laser pulse in ambient air and 10−2 Torr vacuum. Characterization included X-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy. Irradiation in vacuum led to re-distribution of components within the first ∼35 nm beneath the surface. Irradiation in air increased the concentration of Al2O3 in the same region. Irradiation increased the RMS surface roughness by a factor of 10 in both environments (from 3.5 to 36 nm). On the other hand, Al films irradiated in air do not oxidize measurably with a single laser pulse. Model calculations indicate that a single laser pulse (∼16 MW cm−2) can increase the local temperature of cermet from 300 to 1200 K. We interpret the observed transformations as a result of local heating and, in air, as accompanying thermal oxidation.