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arXiv · 1904.04941

Quenching of exciton recombination in strained two-dimensional monochalcogenides

J. J. Esteve-Paredes·Sahar Pakdel·J. J. Palacios
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Abstract

We predict that long-lived excitons with very large binding energies can also exist in a single or few layers of monochalcogenides such as GaSe. Our theoretical study shows that excitons confined by a radial local strain field are unable to recombine despite of electrons and holes co-existing in space. The localized single-particle states are calculated in the envelope function approximation based on a three-band $\boldsymbol{k}\cdot \boldsymbol{p}$ Hamiltonian obtained from DFT calculations. The binding energy and the decay rate of the exciton ground state are computed after including correlations in the basis of electron-hole pairs. The interplay between the localized strain and the caldera-type valence band, characteristic of few-layered monochalcogenides, creates localized electron and hole states with very different quantum numbers which hinders the recombination even for singlet excitons.

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J. J. Esteve-Paredes, Sahar Pakdel, J. J. Palacios. 2019-04-09. Quenching of exciton recombination in strained two-dimensional monochalcogenides. https://doi.org/10.1103/physrevlett.123.077402

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