Strongly-bound excitons and trions in anisotropic 2D semiconductors

Abstract

Monolayer and few-layer phosphorene are anisotropic quasi-two-dimensional (quasi-2D) van der Waals (vdW) semiconductors with a linear-dichroic light-matter interaction and a widely-tunable direct-band gap in the infrared frequency range. Despite recent theoretical predictions of strongly-bound excitons with unique properties, it remains experimentally challenging to probe the excitonic quasiparticles due to the severe oxidation during device fabrication. In this study, we report observation of strongly-bound excitons and trions with highly-anisotropic optical properties in intrinsic bilayer phosphorene, which are protected from oxidation by encapsulation with hexagonal boron nitride (hBN), in a field-effect transistor (FET) geometry. Reflection contrast and photoluminescence spectroscopy clearly reveal the linear-dichroic optical spectra from anisotropic excitons and trions in the hBN-encapsulated bilayer phosphorene. The optical resonances from the exciton Rydberg series indicate that the neutral exciton binding energy is over 100 meV even with the dielectric screening from hBN. The electrostatic injection of free holes enables an additional optical resonance from a positive trion (charged exciton) ~ 30 meV below the optical bandgap of the charge-neutral system. Our work shows exciting possibilities for monolayer and few-layer phosphorene as a platform to explore many-body physics and novel photonics and optoelectronics based on strongly-bound excitons with two-fold anisotropy.

arXiv comment20 pages, 4 figures, Sangho Yoon, Taeho Kim contributed equally to this work

References in corpus (29)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Black phosphorus field-effect transistors
• Rediscovering Black Phosphorus: A Unique Anisotropic 2D Material for Optoelectronics and Electronics
• Observation of tightly bound trions in monolayer MoS2
• Exciton Binding Energy and Nonhydrogenic Rydberg Series in Monolayer WS2
• Excitons in atomically thin transition metal dichalcogenides
• Optical Spectrum of MoS${}_2$: Many-body Effects and Diversity of Exciton States
• Electrical Control of Two-Dimensional Neutral and Charged Excitons in a Monolayer Semiconductor
• Moiré Excitons in Van der Waals Heterostructures
• Signatures of moiré-trapped valley excitons in MoSe${}_2$/WSe${}_2$ heterobilayers
• Observation of Moiré Excitons in WSe2/WS2 Heterostructure Superlattices
• BerkeleyGW: A Massively Parallel Computer Package for the Calculation of the Quasiparticle and Optical Properties of Materials and Nanostructures
• Direct Observation of Layer-Dependent Electronic Structure in Phosphorene
• Photovoltaic effect in few-layer black phosphorus PN junctions defined by local electrostatic gating
• Evidence of high-temperature exciton condensation in 2D atomic double layers
• Screening and Many-Body Effects in Two-Dimensional Crystals: Monolayer MoS${}_2$
• Truncation of Periodic Image Interactions for Confined Systems
• Infrared fingerprints of few-layer black phosphorus
• Revealing the Biexciton and Trion-exciton Complexes in BN Encapsulated WSe2
• Neutral and Charged Inter-Valley Biexcitons in Monolayer MoSe${}_2$
• Thickness-Controlled Black Phosphorus Tunnel Field-Effect Transistor for Low Power Switches
• Coulomb-hole summations and energies for GW calculations with limited number of empty orbitals: a modified static remainder approach
• Determination of layer-dependent exciton binding energies in few-layer black phosphorus
• Coulomb-bound four- and five-particle valleytronic states in an atomically-thin semiconductor
• Excitons in anisotropic 2D semiconducting crystals
• Biexciton fine structure in monolayer transition metal dichalcogenides
• All-optical trion generation in single walled carbon nanotubes
• Non-uniform sampling schemes of the Brillouin zone for many-electron perturbation-theory calculations in reduced dimensionality
• Theoretical investigation of electron-hole complexes in anisotropic two-dimensional materials

Cited by in corpus (6)

• Signatures of Dimensionality and Symmetry in Exciton Bandstructure: Consequences for Time-Evolution
• Layer-dependent exciton polarizability and the brightening of dark excitons in few-layer black phosphorus
• Magnetoexcitons in phosphorene monolayers, bilayers, and van der Waals heterostructures
• When Cubic Is Not Isotropic: Phonon-Exciton Decoupling in CuInSnS${}_4$ Single Crystals
• Interaction effects on electronic Floquet spectra: Excitonic effects
• Electric field tunable magnetoexcitons in Xenes-hBN-TMDC, Xenes-hBN-BP, and Xenes-hBN-TMTC heterostructures