Intrinsic and Extrinsic Defect-related Excitons in TMDCs

Abstract

We investigate an excitonic peak appearing in low-temperature photoluminescence of monolayer transition metal dichalcogenides (TMDCs), which is commonly associated with defects and disorder. First, to uncover the intrinsic origin of defect-related excitons, we study their dependence on gate voltage, excitation power, and temperature in a prototypical TMDC monolayer, $Mo{S}_2$. We show that the entire range of behaviors of defect-related excitons can be understood in terms of a simple model, where neutral excitons are bound to ionized donor levels, likely related to sulphur vacancies, with a density of $7\cdot 10^{11}c{m}^{-2}$. Second, to study the extrinsic origin of defect-related excitons, we controllably deposit oxygen molecules in-situ onto the surface of $Mo{S}_2$ kept at cryogenic temperature. We find that in addition to trivial p-doping of $3\cdot 10^{12}c{m}^{-2}$, oxygen affects the formation of defect-related excitons by functionalizing the vacancy. Combined, our results uncover the origin of defect-related excitons, suggest a simple and conclusive approach to track the functionalization of TMDCs, benchmark device quality, and pave the way towards exciton engineering in hybrid organic-inorganic TMDC devices.

arXiv comment15 pages, 4 figures, including Supplementary information with 6 pages and 5 figures

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Cited by in corpus (13)

• Enhanced Light-Matter Interaction in Two-Dimensional Transition Metal Dichalcogenides
• Strain control of hybridization between dark and localized excitons in a 2D semiconductor
• Spin/valley coupled dynamics of electrons and holes at the ${\text{MoS}}_2-{\text{MoSe}}_2$ interface
• Ultrafast photocurrents in MoSe${}_2$ probed by terahertz spectroscopy
• Extrinsic localized excitons in patterned 2D semiconductors
• Photoluminescence and charge transfer in the prototypical 2D/3D semiconductor heterostructure MoS${}_2$/GaAs
• Nonlocal Exciton-Photon Interactions in Hybrid High-Q Beam Nanocavities with Encapsulated MoS${}_2$ Monolayers
• Bound excitons and bandgap engineering in violet phosphorus
• Sublattice dependence and gate-tunability of midgap and resonant states induced by native dopants in Bernal-stacked bilayer graphene
• Nonclassical Light from Exciton Interactions in a Two-Dimensional Quantum Mirror
• Phonon-mediated exciton capture in Mo-based transition metal dichalcogenides
• Motion of 2D exciton in momentum space leads to pseudospin distribution narrowing on the Bloch Sphere
• Angular Emission Properties of Strained Transition-Metal Dichalcogenides