DEPTH DISTRIBUTION OF DEUTERIUM ATOMS AND MOLECULES IN BERYLLIUM IMPLANTED WITH D-IONS

In-depth concentration profiles of deuterium atoms and molecules in be ryllium implanted with 9 keV D ions to fluences, Phi, in the range fro m 6 x 10(19) to 9 x 10(22) D/m(2) at temperatures, T-irr, of 300 and 7 00 K have been determined using SIMS and RGA (residual gas analysis) m easurements in the course of surface sputtering. The microstructure of implanted specimens was studied by TEM. Implanted deuterium is retain ed in Be matrix in the form of both D atoms and D-2 molecules. The tot al amount of gas captured within the sub-surface layer of similar to 7 00 nm in thickness as a result of implantation at 300 and 700 K reache s 4 x 10(21) and 1 x 10(21) D/m(2), correspondingly. The ratio of deut erium quantities retained in the form of atoms and molecules, Q(D):Q(D 2), varies from 1:3 for T-irr = 300 K to 1:4 for T-irr = 700 K. At T-i rr = 300 K the concentration of D-2 molecules at the depth of the ion mean range reaches its maximum of 4 x 10(27) molecules/m(3) at Phi app roximate to 2 x 10(21) D/m(2). The molecules are present in tiny bubbl es which show a tendency toward interconnection at higher fluences. At T-irr = 700 K, along with relatively small facetted bubbles (near the very surface), large oblate gas-filled cavities and channels forming extended labyrinths appear and they accumulate most of the injected ga s. The maximum D-2 concentration in the latter case is of 1 x 10(27) m olecules/m(3). The high concentration of D atoms in the ion stopping z one after implantation at T-irr = 300 and 700 K (about 2 x 10(27) and 1 x 10(27) atoms/m(3), respectively) is attributed to deuterium (i) tr apped in radiation vacancies, (ii) adsorbed on the walls of bubbles an d channels and (iii) bonded to/by BeO formed on the surface and presen t in the form of metallurgical inclusions in the bulk.