Exposing the trion's fine structure by controlling the carrier concentration in hBN-encapsulated MoS₂

Abstract

Atomically thin materials, like semiconducting transition metal dichalcogenides, are highly sensitive to the environment.

Revealing the impact of strain in the optical properties of bubbles in monolayer MoSe2

“…For instance, recent experiments in ML MoS 2 revealed that doping effects drastically modify the exciton and trion g-factors 84 and that the fine structure of trions is indeed relevant, with different g-factors associated to different trion states. 85 Furthermore, recent calculations have shown that the interplay of doping and dielectric confinement can significantly alter the fine structure of excitons and trions. 86 Although there has been some recent developments on the theory of magneto-excitons [87][88][89] and doping effects on trions, 77,86,90 a more complete picture that incorporates magnetic field, strain effects, doping, and dielectric confinement on an equal footing is still missing.…”

Broadband infrared study of pressure-tunable Fano resonance and metallization transition in 2H-$$\hbox {MoTe}_2$$

“…Within this still debated picture, the role played by intrinsic doping in the metallization process has never been adequately considered, although experimental evidence indicates that defect-related intra-gap levels strongly contribute to the optical and electronic response of semiconducting TMDs 16 , 17 . Photoluminescence (PL) spectra of few-layers compounds exhibit excitonic bands ascribable to radiative recombination processes involving doping states 18 – 20 , and resistivity measurements show that these extra levels significantly modify the transport properties of the samples, even when the doping is unintentional and, thus, the correspondent carrier density very low 17 .…”

Upconversion photoluminescence excitation reveals exciton–trion and exciton–biexciton coupling in hBN/WS$$_{2}$$/hBN van der Waals heterostructures

“…In addition to neutral excitons, a manifold of exciton complexes may be formed with binding energies of tens of meV [6][7][8] ; however, their identification in optical spectra was beyond the reach of simple structures exfoliated directly on standard SiO 2 /Si substrates 9 . Recent progress in elaborating high-quality van der Waals (vdW) heterostructures based on hBN-encapsulated TMDC monolayers allows for observing the subtle optical properties of the exciton complexes thus offering the exploration of many-body effects including electron-electron and electron-phonon interactions [10][11][12][13][14][15][16][17] .…”

“…Recent progress in elaborating high-quality van der Waals (vdW) heterostructures based on hBN-encapsulated TMDC monolayers allows for observing the subtle optical properties of the exciton complexes thus offering the exploration of many-body effects including electron-electron and electron-phonon interactions [10][11][12][13][14][15][16][17] . For W-based vdW structures, electron-electron interactions manifest themselves in a trion photoluminescence (PL) line splitting into an inter-valley triplet and intra-valley singlet whose energies are separated by about 6 meV 6,7,18 . Alternatively, the electron-electron coupling may yield the observation of the biexciton fine structure 19 .…”