Solid-phase epitaxy of Ni-doped amorphous Si films on crystalline Si substrates was investigated. It was found that the crystallization mode of the amorphous films depended strongly upon the Ni concentration. Below about 5 x 1018/cm3, redistribution of Ni into the crystalline substrate occurred and re-growth was controlled by a normal ordinary thermally-activated solid-phase epitaxial crystallization process. On the other hand, above 5 x 1018/cm3 segregation of Ni in the amorphous films was observed and crystallization was driven by impurity-enhanced solid-phase epitaxial crystallization and/or silicide-mediated crystallization in the bulk of the amorphous film. The redistribution of Ni during crystallization could be described in terms of an effective distribution coefficient which accounted for the actual crystallization rate of amorphous Si and for Ni diffusivity in amorphous Si. The dissolution of implantation-induced (311) defects was observed in samples which exhibited Ni diffusion into the crystalline phase during ordinary solid-phase epitaxial crystallization. This indicated annealing and/or suppression of (311) defects due to Ni which accumulated in the region of end-of-range defects.

Nickel Distribution in Crystalline and Amorphous Silicon during Solid-Phase Epitaxy of Amorphous Si A.J.Kuznetsov, B.G.Svensson, O.Nur, L.Hultman: Journal of Applied Physics, 1998, 84[12], 6644-9