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 we re deposited by reactive sputter deposition and, subsequently, irradiated w ith a single 1064 nm laser pulse in ambient air and 10(-2) Torr vacuum. Cha racterization included X-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy. Irradiation in vacuum led to re-dis tribution of components within the first similar to 35 nm beneath the surfa ce. Irradiation in air increased the concentration of Al2O3 in the same reg ion. Irradiation increased the RMS surface roughness by a factor of 10 in b oth environments (from 3.5 to 36 nn). On the other hand. Al films irradiate d in air do not oxidize measurably with a single laser pulse. Model calcula tions indicate that a single laser pulse (similar to 16 MW cm(-2)) can incr ease the local temperature of cermet from 300 to 1200 K. We interpret the o bserved transformations as a result of local heating and, in air, as accomp anying thermal oxidation. (C) 2001 Elsevier Science B.V. All rights reserve d.