Modification of optoelectronic properties of TMDC monolayers by ion implantation

The efficient integration of 2D materials, like graphene, transition metal dichalcogenides (TMDs) and h-BN into the current electronic device technology requires mastering the techniques of effective tuning of their optical, electronic and magnetic properties. It is crucial to understand how we can tune their conductivity (e.g. n-type or p-type doping), induced ferromagnetism, or valley polarization. For the conventional bulk semiconductors, ion implantation is the most developed method to do this.
In this work, we have investigated the optical and structural properties of different TMDCs modified by ion implantation. We have demonstrated the applicability of ion implantation and post-implantation non-equilibrium thermal processing for tuning the carrier concentration in 2D materials. We demonstrate p-type and n-type doping in TMDCs flakes (starting with 1 ML) realized by low-energy ion implantation of P+ and Cl+ ions through a thin capping layer followed by millisecond-range flash lamp annealing (FLA). We further show that FLA for 3 ms is enough to recrystallize implanted MoSe2 and remove ion induced defects.
The comparison between the density functional theory calculations and experimental temperature-dependent micro-Raman spectroscopy data indicates that Cl atoms are incorporated into the atomic network of MoSe2 as substitutional donor impurities. Our results clearly indicate that using our experimental approach, the conventional ion implanters can easily be used to modify the optical, electronic and magnetic properties of various 2D materials on demand