The mechanism of ion induced amorphization in Si

Damage build up and amorphization in Si, induced by 25 keV Si 5 cluster ions and similar mass Cs ions have been studied using transmission electron microscopy and channeling Rutherford backscattering spectrometry. Amorphization is found to be a nucleation and growth process, under the direct impact mechanism. A transition to a completely amorphized state is indicated at a dose of around 17 eV/atom, which is higher than 6-12 eV/atom as predicted by simulations. This indicates a partial suppression of the direct impact mechanism due to recrystallization induced by recoils. At a dose above the amorphization threshold, the amorphous-to-crystalline (a/c) interface is found to be smooth. The smooth a/c interface indicates a transition to a stress relaxed amorphous phase in line with earlier observations.