Giant enhancement of material damage associated to electronic excitation during ion irradiation: The case of LiNbO3

The structural damage induced by ion irradiation on dielectric materials and associated device degradation has been, so far, explained on the basis of collisional processes mostly ignoring the electronic excitation. Recent work, focused on lithium niobate, offers conclusive evidence that at high ion energy and moderate mass (A >= 15) electronic excitation may induce a giant enhancement over the damage rate due to nuclear collisions. As a consequence the material becomes amorphized at irradiation fluences far below those required for nuclear collisions alone. These results are expected to have a deep impact on many technologies including storage of radioactive waste, radiation-resistant materials for fusion reactors, life-time of components and devices in space missions, nanopatterning in electronics and photonics, and possibly heavy-ion therapy in medicine. The role of electronic excitation for the generation of point defects by swift ion irradiation on LiNbO3 has been assessed and compared to the effect of elastic nuclear collisions. For sufficiently high stopping powers S. the electronic generation rate is over where dominant over the collision generation rate and leads to lattice amorphization at much lower irradiation fluences. a, illustrated in the figure for F ions at 22 MeV. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim