Ultrafast carrier dynamics in high-density photo-doped MoS ₂ : monolayer vs multilayer

Monolayer and multilayer MoS 2 are extremely fascinating materials for optoelectronics, particularly in scenarios involving high excitation carrier densities. Consequently, it is essential to understand the various processes and their associated time scales in monolayer and multilayer two-dimensional materials under such high excitation densities. Here, We demonstrate that carrier dynamics in monolayer and multilayer MoS 2 exhibit distinctly different behaviors above the Mott density, with monolayers showing faster carrier relaxation and enhanced many-body interactions compared to multilayers. Despite the similarity in band structure near the K -point and the formation of A-excitons, pronounced differences in the transient response are observed, highlighting the influence of the overall band structure. Exciton dissociation, bandgap renormalization, and intervalley relaxation play a consequential role in dictating the ultrafast transient properties of these samples. The study in this paper provides a detailed understanding of the fundamental optoelectronic properties of the two-dimensional MoS 2 at high excitation densities, paving the way for its potential applications in various photonic and optoelectronic domains.