Optical Properties of MoSe2 Monolayer Implanted with Ultra-Low-Energy Cr Ions

This paper exploresthe optical properties of an exfoliatedMoSe(2) monolayer implanted with Cr+ ions, acceleratedto 25 eV. Photoluminescence of the implanted MoSe2 revealsan emission line from Cr-related defects that is present only underweak electron doping. Unlike band-to-band transition, the Cr-introducedemission is characterized by nonzero activation energy, long lifetimes,and weak response to the magnetic field. To rationalize the experimentalresults and get insights into the atomic structure of the defects,we modeled the Cr-ion irradiation process using ab initio moleculardynamics simulations followed by the electronic structure calculationsof the system with defects. The experimental and theoretical resultssuggest that the recombination of electrons on the acceptors, whichcould be introduced by the Cr implantation-induced defects, with thevalence band holes is the most likely origin of the low-energy emission.Our results demonstrate the potential of low-energy ion implantationas a tool to tailor the properties of two-dimensional (2D) materialsby doping.

Automated summary

This paper investigates the optical properties of an exfoliated MoSe(2) monolayer implanted with Cr+ ions accelerated to 25 eV. The photoluminescence of implanted MoSe2 exhibits an emission line from Cr-related defects, which is only observed under weak electron doping. Unlike band-to-band transitions, the emission introduced by Cr is characterized by nonzero activation energy, long lifetimes, and weak response to the magnetic field. By modeling the Cr-ion irradiation process using ab initio molecular dynamics simulations and electronic structure calculations, the authors provide insights into the atomic structure of the defects, suggesting recombination of electrons on acceptors with valence band holes as the most likely origin of the low-energy emission. The results demonstrate the potential of low-energy ion implantation as a doping tool to tailor the properties of two-dimensional materials.