Revealing the many-body interactions and valley-polarization behavior in Re-doped MoS2 monolayers

Abstract

Substitutional doping has proved to be one of the most important approaches to tune and improve the opto-electronic performance of traditional semiconductors. Similarly, controllable substitution of cations in two-dimensional layered materials can effectively modify and manipulate the band structures, which help to explore sciences and broaden the related applications. In this paper, the salt-assisted one-step chemical vapor deposition method was used to achieve Re substitution in MoS2 monolayers. High-resolution scanning transmission electron microscopy confirms the substitution of Re atoms in Mo sites. X-ray photoelectron spectroscopy and micro-photoluminescence (PL) characterization studies suggest that the Re substitution introduces typical n-type doping in MoS2 monolayers, resulting in the distinct many-body interactions in the doped sample with a higher trion ratio than in the pristine sample in the wide temperature window. The result is further confirmed by the shorter recombination lifetime observed in the Re-doped sample acquired by time-resolved PL measurements. More intriguingly, the circularly polarized PL characterization studies demonstrate that Re doping can improve the valley polarization of the MoS2 monolayer. Our work provides a deep understanding of the optical properties and the associated many-body interactions in the Re-doped MoS2 system and offers a potential way to enhance the valley polarization for spin-/valley-photonic applications.