The defect structure of He+- and H+-implanted crystals was investigated means of micro-Raman scattering and infra-red reflection spectroscopy. Analysis of the data led to the conclusion that the defects which were introduced by He+ implantation had a non-point nature, and were instead likened to large clusters having a new crystalline structure and a specific lattice vibration spectrum. In case of H+-implanted samples, the main lattice defects were found to be of point nature and introduced only weak crystalline disorder.

Comparative Study of Defects Induced by Proton and Helium Implantation in LiNbO3 Crystals. S.M.Kostritskii, P.Moretti: Radiation Effects and Defects in Solids, 1999, 150[1-4], 543-8