Electron-hole pair condensation in Graphene/MoS2 heterointerface

TL;DR

This paper reports the first observation of electron-hole pair condensation in a graphene/MoS2 heterointerface at 10K, demonstrating a new platform for high-temperature excitonic Bose-Einstein condensation.

Contribution

It provides experimental evidence of electron-hole pair condensation in a graphene/MoS2 heterostructure at 10K, with suppressed recombination and high BEC temperature, advancing excitonic quantum states.

Findings

Vanished Hall drag voltage indicating e-h pair condensation

High BEC temperature of 10K, much higher than in quantum wells

Interfacial properties dominate excitonic transport

Abstract

Excitons are electron-hole (e-h) pair quasiparticles, which may form a Bose-Einstein condensate (BEC) and collapse into the phase coherent state at low temperature. However, because of ephemeral strength of pairing, a clear evidence for BEC in electron-hole system has not yet been observed. Here, we report electron-hole pair condensation in graphene (Gr)/MoS2 heterointerface at 10K without magnetic field. As a direct indication of e-h pair condensation, we demonstrate a vanished Hall drag voltage and the resultant divergence of drag resistance. While strong excitons are formed at Gr/MoS2 heterointerface without insulating layer, carrier recombination via interlayer tunneling of carriers is suppressed by the vertical p-Gr/n-MoS2 junction barrier, consequently yielding high BEC temperature of 10K, ~1000 times higher than that of two-dimensional electron gas in III-V quantum wells. The observed excitonic transport is mainly governed by the interfacial properties of the Gr/MoS2 heterostructure, rather than the intrinsic properties of each layer. Our approach with available large-area monolayer graphene and MoS2 provides a high feasibility for quantum dissipationless electronics towards integration.