Correlated disorder by defects clusters in LiNbO3 single crystals after crystal ion-slicing

LiNbO3 (LNO) is a material suitable for high-frequency and wideband RF filters as well as photonic applications due to its outstanding piezoelectric and optical properties. Applications such as thin-film bulk acoustic wave resonators or highly confined electro-optic modulators require thin films, which are still challenging to be obtained with the necessary crystalline quality by deposition methods. Alternatively to deposition, crystal ion-slicing (CIS) or Smart CutTM enables obtaining thin films hundreds of nanometers thick from the bulk single-crystal utilizing high-energy and dose implantation of light atoms. The price to pay is the partial degradation of the initial crystalline perfection, which translates to a degradation of the piezoelectric performance of the material if the CIS-induced damage is not eliminated. This work aims to understand the physics of the recrystallization process of the CIS-damaged LNO crystal upon thermal annealing. The study of the coherent and diffuse scattering by high-resolution X-ray diffraction, complemented by micro-Raman backscattering spectroscopy and Transmission Electron Microscopy (TEM), allowed to study the recovery of the crystallinity from the CIS-induced lattice strain and stress and the progressive reduction of the defects clusters dimension.