Surface modifications of LiNbO3 single crystals induced by swift heavy ions

Single crystals of LiNbO3 (Y-cut orientation) have been irradiated at GANIL using different ions (Sn-112, Gd-155 and U-238) accelerated in the GeV range. All the irradiations were performed at room temperature, with fluences extending from 10(10) to 10(12) ions cm(-2). Rutherford backscattering spectrometry in channeling geometry (RBS-C) was employed to investigate the lattice disorder resulting from the high electronic stopping power (dE/dx)(e) (between 18 and 40 keV nm(-1)). Surface swelling of the irradiated samples was evidenced using a profilometer, in conjunction with direct observations in the nanometer scale by means of atomic force microscopy (AFM). According to RBS-C analysis, the damage cross section A(d) varies from 4 x 10(-13) to 1.4 x 10(-12) cm(2) and depends on both (dE/dx)(e) and the velocity of the incident ions. A correlation was pointed out between the height of the out of plane step and the (dE/dx)(e)-induced damage. AFM observations, performed on samples irradiated at the lowest fluences, indicate a significant broadening of the latent track radius at the surface.