Attraction of indirect excitons in van der Waals heterostructures with three semiconducting layers

Abstract

We study a capacitor made of three monolayers of transition metal dichalcogenide (TMD) separated by hexagonal Boron Nitride (hBN). We assume that the structure is symmetric with respect to the central layer plane. The symmetry includes the contacts: if the central layer is contacted by the negative electrode, both external layers are contacted by the positive one. As a result a strong enough voltage $V$ induces electron-hole dipoles (indirect excitons) pointing towards one of the external layers. Antiparallel dipoles attract each other at large distances. Thus, the dipoles alternate in the central plane forming a 2D antiferroelectric with negative binding energy per dipole. The charging of a three-layer device is a first order transition, and we show that if $V_1$ is the critical voltage required to create a single electron-hole pair and charge this capacitor by $e$, the macroscopic charge $Q_c=eS{n}_c$ ($S$ is the device area) enters the three-layer capacitor at a smaller critical voltage $V_c<V_1$. In other words, the differential capacitance $C(V)$ is infinite at $V=V_c$. We also show that in a contact-less three-layer device, where the chemically different central layer has lower conduction and valence bands, optical excitation creates indirect excitons which attract each other, and therefore form antiferroelectric exciton droplets. Thus, the indirect exciton luminescence is red shifted compared to a two-layer device.

References in corpus (12)

• Observation of Long-Lived Interlayer Excitons in Monolayer MoSe2-WSe2 Heterostructures
• High-temperature superfluidity with indirect excitons in van der Waals heterostructures
• Large capacitance enhancement and negative compressibility of two-dimensional electronic systems at LaAlO${}_3$/SrTiO${}_3$ interfaces
• Excitonic condensation in a symmetric electron-hole bilayer
• Probing the inter-layer exciton physics in a MoS${}_2$/MoSe${}_2$/MoS${}_2$ van der Waals heterostructure
• Anomalously large capacitance of a plane capacitor with a two-dimensional electron gas
• Excitons and biexcitons in symmetric electron-hole bilayers
• Enhanced interlayer neutral excitons and trions in trilayer van der Waals heterostructures
• Phase diagram of bilayer electron-hole plasmas
• The effect of electron dielectric response on the quantum capacitance of graphene in a strong magnetic field
• Giant capacitance of a plane capacitor with a two-dimensional electron gas in a magnetic field
• Cooperative Charging in a Nanocrystal Assembly Gated By Ionic Liquid

Cited by in corpus (6)

• Broken mirror symmetry in excitonic response of reconstructed domains in twisted MoSe${}_2$/MoSe${}_2$ bilayers
• Quantum phase transitions of tri-layer excitons in atomically thin heterostructures
• Evidence for Exciton Crystals in a 2D Semiconductor Heterotrilayer
• Quantum supercapacitors
• Attractive and repulsive dipolar interaction in bilayers of indirect excitons
• Crystal Phases of Charged Interlayer Excitons in van der Waals Heterostructures