Electron beam induced regrowth of ion implantation damage in Si and Ge

Si and Ge samples of different crystal orientations were implanted at room temperature with Xe+ ions to a dose around 10(11) cm(-2); this low dose produces spatially isolated amorphous zones. The samples were subsequently irradiated in a transmission electron microscope with electrons having energy from 25 to 300 keV. Complete crystallization occurred for some amorphous zones, but others only partially crystallized. The regrowth rate depended on the electron energy and the orientation of the crystal. With decreasing electron energy, the regrowth rate first decreased and then increased. The change in rate occurred at an electron energy just below the threshold displacement energy. For Ge, the sub-threshold electron process is faster for (001) than for (110) orientations, and for Si, it is faster for (001) than (111). For the sub-threshold electron process, we suggest that electron energy loss processes provide the energy for the induced crystallization. (C) 1999 Elsevier Science B.V. All rights reserved.