An experimental study, using transmission electron microscopy, was made of the kinetics of amorphization and of recrystallization of Ge during ion implantation (Ge, P and B) and further annealing. As in Si, the crystalline to amorphous phase transition occurred through the linear accumulation of damage with the dose until a certain threshold was reached above which the material turns amorphous. It was shown that the critical damage energy density model could be used in germanium to predict the existence, position and extension of amorphous layers resulting from the implantation of ions for almost all mass/energy/dose combinations reported here and in the literature. During annealing, these amorphous layers recrystallized via solid-phase epitaxy, obeying an Arrhenius-type law. It was observed that this re-growth resulted in the formation of extended defects of interstitial type. During annealing these defects evolved in size and density following an Ostwald ripening mechanism which became non-conservative (defects evaporated) as the temperature was increased to 600C. These results had important implications for the modelling of diffusion of implanted dopant in Ge. Transient diffusion could also exist in Ge; driven by an interstitial component not usually evident under equilibrium conditions.

Amorphization, Recrystallization and End of Range Defects in Germanium. A.Claverie, S.Koffel, N.Cherkashin, G.Benassayag, P.Scheiblin: Thin Solid Films, 2010, 518[9], 2307-13