The mechanism of ion induced amorphisation 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 back-scattering spectrometry. The threshold dose for amorphisation is found to be just below ∼ 15 eV/atom with saturation occurring above 17 eV/atom. Amorphisation is seen to be a nucleation and growth process with the direct impact mechanism suppressed by recoil induced recrystallization. At a dose above the amorphization threshold, unlike the lower dose case, the amorphous-to-crystalline (a/c) interface is found to be smooth. The smooth a/c interface, as seen for a high dose, indicates a transition to a stress relaxed amorphous phase in line with earlier observations.