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Exciton manifolds in highly ambipolar doped WS₂
Publikationstyp
Journal Article
Date Issued
2022-09-01
Sprache
English
Author(s)
Journal
Volume
12
Issue
18
Article Number
3255
Citation
Nanomaterials 12 (18): 3255 (2022)
Publisher DOI
Scopus ID
Publisher
MDPI
The disentanglement of single and many particle properties in 2D semiconductors and their dependencies on high carrier concentration is challenging to experimentally study by pure optical means. We establish an electrolyte gated WS (Formula presented.) monolayer field-effect structure capable of shifting the Fermi level from the valence into the conduction band that is suitable to optically trace exciton binding as well as the single-particle band gap energies in the weakly doped regime. Combined spectroscopic imaging ellipsometry and photoluminescence spectroscopies spanning large n- and p-type doping with charge carrier densities up to 10 (Formula presented.) cm (Formula presented.) enable to study screening phenomena and doping dependent evolution of the rich exciton manifold whose origin is controversially discussed in literature. We show that the two most prominent emission bands in photoluminescence experiments are due to the recombination of spin-forbidden and momentum-forbidden charge neutral excitons activated by phonons. The observed interband transitions are redshifted and drastically weakened under electron or hole doping. This field-effect platform is not only suitable for studying exciton manifold but is also suitable for combined optical and transport measurements on degenerately doped atomically thin quantum materials at cryogenic temperatures.
Subjects
dielectric functions
electrolyte gating
exciton binding energy
excitons
spectroscopic imaging ellipsometry
transition metal dichalcogenides
DDC Class
540: Chemistry
620: Engineering