One-dimensional analytical model for oxide thin film growth on Ti metal layers during laser heating in air

This paper presents the theoretical and experimental results for oxide thin film growth on titanium films previously deposited over glass substrate. T i films of thickness 0.1 mum were heated by Nd:YAG laser pulses in air. The oxide tracks were created by moving the samples with a constant speed of 2 mm/s, under the laser action. The micro-topographic analysis of the tracks was performed by a microprofiler. The results taken along a straight line perpendicular to the track axis revealed a Gaussian profile that closely ma tches the laser's spatial mode profile, indicating the effectiveness of the surface temperature gradient on the him's growth process. The sample's mic ro-Raman spectra showed two strong bands at 447 and 612 cm associated with the TiO2 structure. This is a strong indication that thermo-oxidation react ions took place at the Ti film surface that reached an estimated temperatur e of 1160 K just due to the action of the first pulse. The results obtained from the numerical integration of the analytical equation which describes the oxidation rate (Wagner equation) are in agreement with the experimental data for film thickness in the high laser intensity region, This shows the partial accuracy of the one-dimensional model adopted for describing the f ilm growth rate. (C) 2001 Elsevier Science B.V, All rights reserved.