640 Applied SurfaceScience36 (1989) 6'10-.647 North-Holland, Amsteldam EXC|MER LASER lNDUCED CRYSTALLIZATION AND OXIDATION OF AMORPHOUS Cr THIN FILMS I. URSU, M.L BIILTEGA, M. DINESCU, I.N. MIHAILESCU, N. POPESCU-POGRION, L. R~BCO Central Institute of Physics, Bucharest, POB MG-6, Romania A.M. PROKHOROV, V.I. KONOV and V.N. TOKAREV Institute of General Physics, Moscow, USSR Received 2 June 1988; accepted for publication 23 July 1988 TEM and TED results are reported on the crystallizationand oxidation of 20 and 30 nm thick amorphous Cr films supported on electron microscopecopper grids when submitted in air to the action of a single excimer laser pulse (~ = 0.308 gin) of 20 ns width (FWHM). The energy incident on the target was varied using calibrated attenuators ensuring, in spots of 0.7 to 0.9 mm diameter, laser intensitiesranging from 0.6 × 10s to 1.2 × 106 W cm- 2. Crystallizationphenomena are noticed beginning from 0.6×105 W cm-2. Crystallizationand oxidation of the thin film not involving full deterioration are seen to occur for laser spot intensities ranging from 0.17 × 106 to 0.27 x 106 W cm- 2. The copper grid meshes(~ ~ 120/Lm) which support the chromium thin film, channel the incident laser beam so that at mesh level in the irradiated spot, temperature gradients develop from the center of the mesh towards its borders. Thus at grid mesh level in the irradiated area, a sequenceof microstructurescould be noticed beginning with a-Cr small crystals followed by a-Cr and Cr304 small crystals, Cr304 and o-Cr203 small crystals and finally large a-Cr203 crystals. 1. Introduction We have previously studied [1-5] the crystallization/recrystallization and oxidation of thin amorphous/polycrystalline Cr films, < 80 nm thick sup- ported on electron microscope grids, under the action of low power (a few W) cw CO2 laser irradiation by TEM and TED techniques. We have shown that depending on the power densities and dwell times, after completion of tile crystallization/recrystallization process, the oxidation proceeds with the, for- mation of a spinel-like T-Cr~O3, which is thereafter accompanied and finally replaced by the formation of stable a-Cr20 3 crystals. In this work we report TEM and TED investigations on the crystallization and oxidation ih air of 20 and 30 nm thick amorphous Cr films supported on eiectron microscope (EM) copper grids under the action of a single laser pulse, 29 ns in width (FWHM), delivered from an excimer laser (;k = 0.308 pm). 0169-4332/89/$03.50 © Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division)