Inducing room-temperature valley polarization of excitonic emission in transition metal dichalcogenide monolayers

Abstract

The lowest energy states in transition metal dichalcogenide (TMD) monolayers follow valley selection rules, which have attracted vast interest due to the possibility of encoding and processing of quantum information. However, these quantum states are strongly affected by the temperature-dependent intervalley scattering causing complete valley depolarization, which is hampering any practical applications of TMD monolayers at room temperature. Therefore, for achieving clear and robust valley polarization in TMD monolayers one needs to suppress parasitic depolarization processes, which is the central challenge in the growing field of valleytronics. Here, in electron-doping experiments on TMD monolayers, we demonstrate that strong doping levels beyond $10^{13}$~cm${}^{-2}$ can induce 61\% and 37\% valley contrast at room temperature in tungsten diselenide and molybdenum diselenide monolayers, respectively. Our results indicate that charged excitons in TMD monolayers can be utilized as quantum units in designing of practical valleytronic devices operating at 300 K.

References in corpus (11)

• Control of valley polarization in monolayer MoS2 by optical helicity
• Valley polarization in MoS2 monolayers by optical pumping
• Excitons in atomically thin transition metal dichalcogenides
• Optical Generation of Excitonic Valley Coherence in Monolayer WSe2
• Polarization and time-resolved photoluminescence spectroscopy of excitons in MoSe2 monolayers
• Optical valley Hall effect for highly valley-coherent exciton-polaritons in an atomically thin semiconductor
• Trion Valley Coherence in Monolayer Semiconductors
• Room Temperature Valley Polarization and Coherence in Transition Metal Dichalcogenide-Graphene van der Waals Heterostructures
• Resonance profiles of valley polarization in single-layer MoS${}_2$ and MoSe${}_2$
• Exciton-to-trion conversion as a control mechanism for valley polarization in room-temperature monolayer WS${}_{\text{2}}$
• Valley Phenomena in the Candidate Phase Change Material WSe${}_{2(1-x)}$Te${}_{2x}$

Cited by in corpus (1)

• An atlas of photonic and plasmonic materials for cathodoluminescence microscopy