DEFECT CREATION BY MEV CLUSTERS IN LINBO3

Single crystals of LiNbO3 (Y-cut orientation) were irradiated at room temperature with 3 MeV C-6(+) and 2.4 MeV C-8(+) clusters provided by CSNSM ''ARAMIS'' accelerator. The electronic stopping power was about 6.5 keV nm(-1) in both cases. The fluences extended from 10(10) to 4 x 10(12) C-6(+) or C-8(+) cm(-2). Rutherford Backscattering Spectrometr y in Channeling geometry (RBS/C) revealed the presence of extended def ects, which cannot be due solely to nuclear stopping and which we ascr ibe to the high density of electronic energy associated with the corre lated electronic stopping of the cluster components. The RBS/C analysi s, providing a lattice disorder profile, confirms this interpretation: the damaged thickness closely corresponds to the cluster components c orrelation length (between 50 and 100 nm). The fluence evolutions of t he disorder ratio, measured at the sample surface for C-6 and C-8 proj ectiles, correspond to damage cross sections close to 1.8 x 10(-13) cm (2) in the two cases.