STRUCTURAL MODIFICATIONS IN HE-IMPLANTED WAVE-GUIDE LAYERS OF LINBO3

He-implanted and heat-treated optical waveguide layers in Y-cut LiNbO3 wafers were studied by means of high-resolution X-ray diffraction. Th e depth-resolved profiles of the lattice parameter were derived from t he measured diffraction spectra as a function of annealing temperature . Using these data, the spatial distribution of the electron density r elated to the post-implantation lattice swelling was determined, which shed light on the waveguide formation in damaged layers. Heat treatme nts at temperatures T > 200 degrees C resulted in the deterioration of waveguide properties due to annealing of the implantation-induced dam age. Lattice recovery was found to be a thermally activated process wi th an activation energy of E(a) = 0.32 +/- 0.03 eV. This is accompanie d by defect clustering, giving rise to diffuse scattering components i n the diffraction spectra.