Molecular dynamics simulation on the effect of dislocation structures on the retention and distribution of helium ions implanted into silicon

To investigate the effect of dislocation structures on the initial formation stage of helium bubbles, molecular dynamics (MD) simulations were used in this study. The retention rate and distribution of helium ions with 2 keV energy implanted into silicon with dislocation structures were studied via MD simulation. Results show that the dislocation structures and their positions in the sample affect the helium ion retention rate. The analysis on the three-dimensional distribution of helium ions show that the implanted helium ions tend to accumulate near the dislocation structures. Raman spectroscopy results show that the silicon substrate surface after helium ion implantation displayed tensile stress as indicated by the blue shift of Raman peaks.