Amorphous pockets in Si: Comparison of coupled molecular dynamics and TEM image contrast simulations with experimental results

The size of collision cascades of heavy ions in silicon as calculated by molecular dynamics or other simulation methods is considerably larger than the size of the amorphous pockets observed by transmission electron microscopy (TEM). Using multislice TEM image contrast simulations with atom coordinates from molecular dynamics simulations, we show that the peripheries of the collision cascades should be visible in the TEM if they existed at the time of analysis. We argue that the most likely reason for the discrepancy is thermal annealing. In order to guarantee exactly the same TEM conditions in the simulation and the experiment, we have performed low-dose Ge, Te, and Pb implantations at cryogenic and room temperature, and use them in the comparison.