Anomalous X-ray reflectivity study of metal oxide thin films

Anomalous X-ray reflectivity measurements have been performed to extract electron density profile as a function of depth. Using a model independent analysis scheme based on distorted wave Born approximation, we have demonstrated that element-specific density profiles in a film can be obtained from reflectivity measurements done at two different X-ray energies, one at an absorption edge of the corresponding metal and another one away from it. The merit of this technique has been demonstrated with the results on high dielectric constant metal oxide Ta2O5 films on Si(001). Our results show different Ta profiles near interfaces for Ta2O5/Si interface and Ta2O5/SiO2 interface, implying different kinetics at these interfaces during annealing process.