In-situ observation of stability of nanosized amorphous zones in Ge

In-situ transmission electron microscopy was used to observe the instability of isolated, nanosized amorphous zones in Ge at elevated temperatures as induced by implantation of 50 keV Kr⁺ and Xe⁺ ions. It was revealed that the lifetime of the amorphous zones is strongly dependent on temperature and the process of dynamic annealing for ion implantation observed is very different from the case of Si. It was also observed that the apparent activation energy for the process induced by Kr⁺ ion implantation is much higher than that induced by Xe⁺ ion implantation. This implies that the formation and disappearance of the amorphous zones is also ion mass dependent and can be well accounted for by the newly-proposed model of energetic beam irradiation-induced soft mode and lattice instability.