Room temperature observation of biexcitons in exfoliated WS2 monolayers

Abstract

Single layers of WS2 are direct gap semiconductors with high photoluminescence (PL) yield holding great promise for emerging applications in optoelectronics. The spatial confinement in a 2D monolayer together with the weak dielectric screening lead to huge binding energies for the neutral excitons as well as other excitonic complexes, such as trions and biexcitons whose binding energies scale accordingly. Here, we report on the existence of biexcitons in mechanically exfoliated WS2 flakes from 78 K up to room temperature. Performing temperature and power dependent PL measurements, we identify the biexciton emission channel through the superlinear behavior of the integrated PL intensity as a function of the excitation power density. On the contrary, neutral and charged excitons show a linear to sublinear dependence in the whole temperature range. From the energy difference between the emission channels of the biexciton and neutral exciton, a biexciton binding energy of 65-70 meV is determined.

arXiv comment21 pages, 7 figures

References in corpus (22)

• Electric Field Effect in Atomically Thin Carbon Films
• Atomically thin MoS2: A new direct-gap semiconductor
• Boron nitride substrates for high-quality graphene electronics
• Observation of tightly bound trions in monolayer MoS2
• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Photovoltaic effect in an electrically tunable van der Waals heterojunction
• Probing Excitonic Dark States in Single-layer Tungsten Disulfide
• Lattice dynamics in mono- and few-layer sheets of WS2 and WSe2
• Entangled Photon Pairs from Semiconductor Quantum Dots
• Non-linear Optical Spectroscopy of Excited Exciton States for Efficient Valley Coherence Generation in WSe2 Monolayers
• Identification of excitons, trions and biexcitons in single-layer WS2
• Binding energies of exciton complexes in transition metal dichalcogenides and effect of dielectric environment
• Analytical approach to excitonic properties of MoS2
• Intervalley biexcitons and many-body effects in monolayer MoS2
• Coherent Electronic Coupling in Atomically Thin MoSe2
• Binding energies and spatial structures of small carrier complexes in monolayer transition metal dichalcogenides via diffusion Monte Carlo
• Optical control of charged exciton states in tungsten disulfide
• Exciton complexes in low dimensional transition metal dichalcogenides
• Excitonic effects in two-dimensional semiconductors: Path integral Monte Carlo approach
• Trion and Biexciton in Monolayer Transition Metal Dichalcogenides
• Spatial Non-Uniformity in Exfoliated WS2 Single layers
• Photoluminescence from localized states in disordered indium nitride

Cited by in corpus (14)

• Charge-tuneable biexciton complexes in monolayer WSe${}_2$
• Revealing the Biexciton and Trion-exciton Complexes in BN Encapsulated WSe2
• Diffusion quantum Monte Carlo study of excitonic complexes in two-dimensional transition-metal dichalcogenides
• Zeeman Splitting and Inverted Polarization of Biexciton Emission in Monolayer WS2
• Guide to optical spectroscopy of layered semiconductors
• Prominent room temperature valley polarization in WS2/graphene heterostructures grown by chemical vapor deposition
• Broadband pump-probe study of biexcitons in chemically exfoliated layered WS${}_2$
• Monolayer WS${}_2$ electro- and photo-luminescence enhancement by TFSI treatment
• Controlling valley splitting and Polarization of dark- and bi-excitons in monolayer WS${}_2$ by a tilted magnetic field
• $\Gamma$-valley assisted intervalley scattering on monolayer and bilayer WS2 revealed by time-resolved Kerr rotation spectroscopy
• Enhanced exciton-exciton collisions in an ultra-flat monolayer MoSe2 prepared through deterministic flattening
• Tensile strain induced brightening of momentum forbidden dark exciton in WS${}_2$
• Electrostatic control of the trion fine structure in transition metal dichalcogenide monolayers
• Electron density control in tungsten diselenide monolayers via photochlorination