Influence of Rhenium Concentration on Charge Doping and Defect Formation in MoS2

TL;DR

This study investigates how varying rhenium concentrations influence charge doping, defect formation, and exciton behavior in MoS2 monolayers, providing insights for optimizing TMD-based electronic and photonic devices.

Contribution

It reveals the effects of Re doping levels on defect clustering, ionization energy, and exciton trapping in MoS2, combining experimental and theoretical approaches.

Findings

Re doping reduces sulfur-site defects at low concentrations.

Re clustering occurs near 2 atom% Re, affecting doping efficiency.

Re clusters create defect states that trap excitons.

Abstract

Substitutionally doped transition metal dichalcogenides (TMDs) are the next step towards realizing TMD-based field effect transistors, sensors, and quantum photonic devices. Here, we report on the influence of Re concentration on charge doping and defect formation in MoS2 monolayers grown by metal-organic chemical vapor deposition. Re-MoS2 films can exhibit reduced sulfur-site defects; however, as the Re concentration approaches 2 atom%, there is significant clustering of Re in the MoS2. Ab Initio calculations indicate that the transition from isolated Re atoms to Re clusters increases the ionization energy of Re dopants, thereby reducing Re-doping efficacy. Using photoluminescence spectroscopy, we show that Re dopant clustering creates defect states that trap photogenerated excitons within the MoS2 lattice. These results provide insight into how the local concentration of metal dopants affect carrier density, defect formation, and exciton recombination in TMDs, which can aid the development of future TMD-based devices with improved electronic and photonic properties.