Excitonic properties of semiconducting monolayer and bilayer MoTe2

Abstract

MoTe2 belongs to the semiconducting transition metal dichalcogenide family with some properties differing from the other well-studied members (Mo,W)(S,Se)2. The optical band gap is in the near infrared region and both monolayers and bilayers may have a direct optical band gap. We first simulate the band structure of both monolayer and bilayer MoTe2 with DFT-GW calculations. We find a direct (indirect) electronic band gap for the monolayer (bilayer). By solving the Bethe-Salpeter equation, we calculate similar energies for the direct excitonic states in monolayer and bilayer. We then study the optical properties by means of photoluminescence (PL) excitation, time-resolved PL and power dependent PL spectroscopy. We identify the same energy for the B exciton state in monolayer and bilayer. Following circularly polarized excitation, we do not find any exciton polarization for a large range of excitation energies. At low temperature (T=10 K), we measure similar PL decay times of the order of 4 ps for both monolayer and bilayer excitons with a slightly longer one for the bilayer. Finally, we observe a reduction of the exciton-exciton annihilation contribution to the non-radiative recombination in bilayer.

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• Measurement of the Spin-Forbidden Dark Excitons in MoS2 and MoSe2 monolayers
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• Direct versus indirect band gap emission and exciton-exciton annihilation in atomically thin molybdenum ditelluride (MoTe${}_2$)
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• Low-loss integrated nanophotonic circuits with layered semiconductor materials
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• Electron recoil effect in electrically tunable MoSe2 monolayers
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• Room temperature infrared photodetectors with hybrid structure based on 2D materials
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• Geometric Stiffness in Interlayer Exciton Condensates
• MoTe2 as a natural hyperbolic material across the visible and the ultraviolet region
• Quantum phase transition of a two-dimensional quadrupolar system
• Quasiparticle and Optical Properties of Carrier-Doped Monolayer MoTe${}_2$ from First Principles
• Luminescence anomaly of dipolar valley excitons in homobilayer semiconductor moiré superlattices
• Charge-carrier complexes in monolayer semiconductors
• The deep-acceptor nature of the chalcogen vacancies in 2D transition-metal dichalcogenides
• Hybrid moiré excitons and trions in twisted MoTe${}_2$-MoSe${}_2$ heterobilayers
• Optical Switching of Moiré Chern Ferromagnet
• Phonon Assisted Exciton Processes in Two-Dimensional Tungsten Monocarbide
• Excitonic Complexes and Optical Gain in Two-Dimensional Molybdenum Ditelluride Well below Mott Transition
• Extremely high excitonic $g$-factors in 2D crystals by alloy-induced admixing of band states
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• Excitonic Transport and Intervalley Scattering in Exfoliated MoSe2 Monolayer Revealed by Four-Wave-Mixing Transient Grating Spectroscopy