ION-DRIVEN PERMEATION AND SURFACE RECOMBINATION COEFFICIENT OF DEUTERIUM FOR COPPER

The flux density of deuterium permeation through polycrystalline copper membrane driven by an ion beam (5 keV D3+) was measured as a function of temperature (80-500-degrees-C) and implantation flux [(0.2-1.0) X 10(15) D atoms cm-2 s-1]. The observed dependence of permeation flux on both parameters changed around 200-300-degrees-C. This was found to be due to the transition in rate-controlling processes. The surface recombination coefficient of deuterium was evaluated from the permeation flux. In order to discuss it, the model for recombination coefficient based on one-dimensional potential-energy surface was extended, taking account of subsurface solution sites. The comparison between the experimentally and theoretically determined values supported the existence of the activation barrier for hydrogen chemisorption on copper.