The lattice sites of implanted 8Li were studied by using the -emission channelling technique. In both materials, tetrahedral interstitial sites were found to be the occupied (60 to 80% in Si, 40 to 60% in Ge) lattice sites following room-temperature implantation. Depending upon the doping characteristics of the sample, up to 55% of the Li was found on bond-center sites in Si after implantation at temperatures of between 425 and 475K. The occupation amounted to up to 40% in Ge after implantation at temperatures of between 325 and 400K. At higher temperatures, the Li occupied increasingly random lattice sites. The change in lattice site, from tetrahedral to bond-centered, was attributed to the onset of interstitial Li diffusion and to its capture by additional defects. The latter were expected to be vacancy-type defects which arose from implantation. The trapping of Li at these defects inhibited its long-range diffusion.

U.Wahl, S.G.Jahn, M.Restle, H.Quintel, H.Hofsäss, Isolde: Materials Science Forum, 1995, 196-201, 115-20