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arXiv · 1705.01996

Exciton-phonon interaction in the strong coupling regime in hexagonal boron nitride

T. Q. P. Vuong·G. Cassabois·P. Valvin·S. Liu·J. H. Edgar·B. Gil
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Abstract

The temperature-dependent optical response of excitons in semiconductors is controlled by the exciton-phonon interaction. When the exciton-lattice coupling is weak, the excitonic line has a Lorentzian profile resulting from motional narrowing, with a width increasing linearly with the lattice temperature $T$. In contrast, when the exciton-lattice coupling is strong, the lineshape is Gaussian with a width increasing sublinearly with the lattice temperature, proportional to $\sqrt{T}$. While the former case is commonly reported in the literature, here the latter is reported for the first time, for hexagonal boron nitride. Thus the theoretical predictions of Toyozawa [Progr. Theor. Phys. 20, 53 (1958)] are supported by demonstrating that the exciton-phonon interaction is in the strong coupling regime in this Van der Waals crystal.

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T. Q. P. Vuong, G. Cassabois, P. Valvin, S. Liu, J. H. Edgar, B. Gil. 2017-05-04. Exciton-phonon interaction in the strong coupling regime in hexagonal boron nitride. https://doi.org/10.1103/physrevb.95.201202

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