Theoretical Phase Diagram for the Room-Temperature Electron-Hole Liquid in Photoexcited Quasi-Two-Dimensional Monolayer MoS₂.

Abstract

Strong correlations between electrons and holes can drive the existence of an electron-hole liquid (EHL) state, typically at high carrier densities and low temperatures. The recent emergence of quasi-two-dimensional (2D) monolayer transition metal dichalcogenides (TMDCs) provides ideal systems to explore the EHL state since ineffective screening of the out-of-plane field lines in these quasi-2D systems allows for stronger charge carrier correlations in contrast to conventional 3D bulk semiconductors and enables the existence of the EHL at high temperatures. Here we construct the phase diagram for the photoinduced first-order phase transition from a plasma of electron-hole pairs to a correlated EHL state in suspended monolayer MoS₂. We show that the quasi-2D nature of monolayer TMDCs and the ineffective screening of the out-of-plane field lines allow for this phase transition to occur at and above room temperature, thereby opening avenues for studying many-body phenomena without the constraint of cryogenics.