Virgin (100) single crystals, and single crystals which contained implanted He, were implanted with 15keV D and H ions to doses ranging from 2 x 1015 to 2 x 1016/cm2. The samples were annealed at temperatures between ambient and 950K. The defects which were produced by H, and the trapping of H at the defects, were monitored by means of photon absorption and positron-beam analysis. The depth distributions of defects could be determined for implantation depths of up to 2000nm. The technique was very sensitive to vacancies and vacancy-clusters; that is, sites with a low electron density. After annealing at 950K, micro-cavities were observed for doses of 2 x 1016/cm2; but not after a 10-times lower dose. During annealing at up to 750K, the point defects were mobile but the defect clusters remained small and H-filled. In samples which already contained micro-cavities, point defects and D arising from D implantation were accumulated by the micro-cavities.

Hydrogen Implantation Defects in MgO. A.Van Veen, H.Schut, A.V.Fedorov, E.A.C.Neeft, R.J.M.Konings, B.J.Kooi, J.T.M.De Hosson: Nuclear Instruments and Methods in Physics Research B, 1999, 147[1-4], 216-20