The ability of high-resolution X-ray diffraction to provide information on atomic diffusion was analyzed. The analysis focussed on the study of Ti-diffused crystalline wave-guide layers. Samples were prepared by depositing a 35nm-thick Ti layer onto 75mm Y-cut niobate wafers, and annealing (995C, 0.5 to 6h). Depth-resolved profiles of the interplanar spacing, derived from X-ray diffraction data, were compared with Ti-concentration profiles which had been measured by means of secondary ion mass spectrometry. It was shown that both results could be used to determine Ti diffusion coefficients. The Ti diffusivity at 995C was estimated to be equal to 6.4 x 10-13cm2/s. Comparison of the techniques produced a numerical factor which related the Ti concentration to the modified lattice parameter, and permitted a quantitative characterization of the extent of lattice contraction due to Ti incorporation. The factor was found to increase with annealing time; thus indicating a variable strain contribution to the structural parameters. The variations were attributed to high-temperature phase transformation processes which accompanied Ti diffusion.

Diffusion and Structural Modification of Ti:LiNbO3, Studied by High-Resolution X-Ray Diffraction. Y.Avrahami, E.Zolotoyabko: Journal of Applied Physics, 1999, 85[9], 6447-52