Effect of defect accumulation on ion-beam damage morphology by electronic excitation in lithium niobate: A MonteCarlo approach

We present a MonteCarlo approach to the non-radiative exciton-decay model recently proposed to describe ion-beam damage in LiNbO3 produced in the electronic excitation regime. It takes into account the statistical (random) spatial distribution of ion impacts on the crystal surface. The MonteCarlo approach is necessary to simulate the evolution of the damage morphology with irradiation fluence from the single track regime to the overlapping track regime. A detailed comparison between the morphologies found for sub-threshold and above threshold irradiations is presented. Moreover, a good representation of the Avrami's type kinetics for amorphization has been achieved and it is in fair accordance with experiment. For moderate fluences where homogeneous amorphous layers are generated, the new approach predicts that the amorphous and crystalline layers are separated by a diffuse (thick) boundary that includes a mixed amorphous-crystalline composition. (c) 2010 Elsevier B.V. All rights reserved.