Surface oxidation kinetics of Cr film by Nd-YAG laser

Surface microstructures of Cr films by Nd-YAG laser oxidation and annealing oxidation were studied by SEM, FESEM, AFM and XRD. Cr films with different grain sizes varying from 30 to 200 nm were obtained with the change of laser parameters. The calculated activation energy is of 1.13 eV and it was less than the lattice diffusion activation energy. Fick's law and average field method was applied to simulate the laser oxidation kinetics in Cr films. The differential form of homogeneous grain growth formula at equivalent constant temperature was used to establish laser oxidation kinetics. The inverse logarithm relation between oxidation rate and laser acting time was observed when the grain sizes of film were in 100-200 nm and it complied with Wagner theory and the parabola kinetics curve. The oxidation kinetics complied with Carbrea-Mott theory when the oxide film grain sizes were less than 100 nm. Cabrera-Mott oxidation kinetics was applied to not only the grain sizes within 10 nm, but also the grain sizes up to 100 nm. This result filled up the blank in the oxidation kinetics with grains sized of 10-100 nm. These results from the laser enhanced desorption which could reach rather deeper layer in the film under laser oxidation.