Low current MeV Au2+ ion-induced amorphization in silicon: Rutherford backscattering spectrometry and transmission electron microscopy study

The amorphization due to MeV Au2+ ion implantation in Si(1 1 1) has been studied using Rutherford backscattering spectrometry/channeling (RBS/C) and transmission electron microscopy (TEM) methods. 1.5 MeV Au2+ ions were implanted into Si(1 1 1) substrates at various fluences at low currents (0.02–0.04 μA cm−2) while the samples were kept at room temperature. The RBS/C results for as-implanted specimen shows the onset fluence for amorphization to be &ap;<f>5×1013</f> ions cm−2 which is much lower than the fluence reported earlier. Selected area diffraction (TEM) for a sample implanted at a of <f>1×1014</f> ions cm−2 confirms the occurrence of the amorphization. Earlier, amorphization studies by Alford and Theodore, using 2.4 MeV gold ions in silicon (1 0 0) reported a threshold fluence of <f>1.8×1015</f> ions cm−2 for amorphization when the implantation was carried out at higher currents (0.2–5 μA cm−2) [J. Appl. Phys. 76 (1994) 7265]. The nuclear energy loss (<f>Sn</f>) for 1.5 MeV gold ions in silicon is &ap;13% greater than the value for 2.4 MeV and cannot be the sole reason for lower threshold fluence for the amorphization. The amorphization at a relatively lower fluence for the low current implantations could be possible due to reduction in the dynamical annealing effects. [Copyright &y& Elsevier]