Suppressed out-of-plane polarizability of free excitons in monolayer WSe${}_2$

Abstract

Monolayer semiconductors are atomically thin quantum wells with strong confinement of electrons in two-dimensional (2D) plane. Here, we experimentally study the out-of-plane polarizability of excitons in hBN-encapsulated monolayer WSe${}_2$ in strong electric fields of up to 1.6 V/nm (16 MV/cm). We monitor free and bound exciton photoluminescence peaks with increasing electric fields at a constant carrier density, carefully compensating for unintentional photodoping in our double-gated device at 4K. We show that the Stark shift is < 0.4 meV despite the large electric fields applied, yielding an upper limit of polarizability α${}_z$ to be ~ 10${}^{-11}$ Dm/V. Such a small polarizability, which is nearly two orders of magnitude smaller than the previously reported value for MoS${}_2$, indicates strong atomic confinement of electrons in this 2D system and highlights the unusual robustness of free excitons against surface potential fluctuations.

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Cited by in corpus (10)

• Giant Stark splitting of an exciton in bilayer MoS${}_2$
• Electronic polarizability as the fundamental variable in the dielectric properties of two-dimensional materials
• Accessing high optical quality of MoS2 monolayers grown by chemical vapor deposition
• Dielectrics for Two-Dimensional Transition Metal Dichalcogenide Applications
• Anomalous Stark Shift of Excitonic Complexes in Monolayer Semiconductor
• Active control of excitonic strong coupling and electroluminescence in electrically driven plasmonic nanocavities
• In-Plane Electric Field Induced Orbital Hybridization of Excitonic States In Monolayer WSe2
• Harmonic to anharmonic tuning of moiré potential leading to unconventional Stark effect and giant dipolar repulsion in WS${}_2$/WSe${}_2$ heterobilayer
• Electrical Control of Excitons in Bare-MoSe2 and MoSe2/NbSe2 Heterostructure
• Interlayer exciton mediated second harmonic generation in bilayer MoS2