Theoretical phase diagram for the room temperature Electron-Hole Liquid in photo-excited quasi-2D monolayer MoS$_2$

TL;DR

This paper presents a theoretical phase diagram showing that photo-induced electron-hole liquids can exist at room temperature in monolayer MoS2 due to strong correlations in quasi-2D systems, enabling room-temperature many-body physics studies.

Contribution

The study provides the first theoretical phase diagram for the electron-hole liquid transition in monolayer MoS2, highlighting the role of quasi-2D effects and screening in enabling room-temperature EHL.

Findings

EHL can form at and above room temperature in monolayer MoS2.

Quasi-2D nature enhances charge correlations compared to bulk semiconductors.

Phase transition is driven by photo-excitation and is first-order.

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-2D monolayer transition metal dichalcogenides (TMDCs) provide 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 enabling the existence of the EHL at high temperatures. Here we construct the phase diagram for the photo-induced first-order phase transition from a plasma of electron-hole pairs to a correlated EHL state in suspended monolayer MoS2. We show that 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.