Modelling of the implantation and the annealing stages of 800 keV 3He implanted tungsten: Formation of nanovoids in the near surface region

The formation of voids in tungsten implanted at room temperature with 800 keV He-3 atoms and subsequently annealed from 300 K to 900 K is modelled using an Object Kinetic Monte Carlo code. Different fluences are investigated ranging from 10(17) to 5 x 10(20) ions m(-2) and comparisons are made with Positron Annihilation Spectroscopy results. Good agreements with the experimental results are obtained regarding the temperature range at which the vacancy clustering occurs and the dependency of the nanovoid size with thence. Despite the small amount of He atoms in the investigated region named "track region", their role is underlined and it is shown that they act as nuclei for the nanovoid formation. The non trivial consequence is that the higher the fluence, the smaller the nanovoids in the track region. (C) 2012 Elsevier B.V. All rights reserved.