Modeling of the impurity-induced silicon nanocone growth by low energy helium plasma irradiation

The formation mechanism of nanocone structure on silicon (Si) surface irradiated by helium plasma has been investigated by experiments and simulations. Impurity (molybdenum) aggregated as shields on Si was found to be a key factor to form a high density of nanocone in our previous study. Here to concrete this theory, a simulation work has been developed with SURO code based on the impurity concentration measurement of the nanocones by using electron dispersive x-ray spectroscopy. The formation process of the nanocone from a flat surface was presented. The modeling structure under an inclining ion incident direction was in good agreement with the experimental result. Moreover, the redeposition effect was proposed as another important process of nanocone formation based on results from the comparison of the cone diameter and sputtering yield between cases with and without the redeposition effect.