Polarization analysis of excitons in monolayer and bilayer transition-metal dichalcogenides
By H. Dery, Yang Song. 2015
138 citations recorded by the source corpus.
The polarization analysis of optical transitions in monolayer and bilayer transition-metal dichalcogenides provides invaluable information on the spin and valley (pseudospin) degrees of freedom. To explain optical properties of a given monolayer transition-metal dichalcogenide, one should consider (i) the order of its spin-split conduction bands, (ii) whether intervalley scattering is prone to phonon bottleneck, (iii) and whether valley mixing by electron-hole exchange can take place. Using these principles, we present a consistent physical picture that elucidates a variety of features in the optical spectra of these materials. We explain the differences between optical transitions in monolayer MoSe$_2$ and monolayer WSe$_2$, finding that indirect excitons in the latter correspond to several low-energy optical transitions that so far were attributed to excitons bound to impurities. A possible mechanism that can explain the vanishing polarization in MoSe$_2$ is discussed. Finally, we consider the effect of an out-of-plane electric field, showing that it can reduce the initial polarization of bright excitons due to a Rashba-type coupling with dark excitons.
Subfields: Electrical and Electronic Engineering, Materials Chemistry
View Paper: https://www.semanticscholar.org/paper/ea0e6a59165bef655e9aee11d28cd7045633c5e3
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In Electrical and Electronic Engineering
In Materials Chemistry
Citations in the corpus
- Optical properties of atomically thin transition metal dichalcogenides: observations and puzzles (2016, background): “The below-exciton emission band observed in S-TMD monolayers might therefore well be due to recombination of dark-exciton states, although activated by disorder or phonons [83, 84].”