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arXiv · 1811.03461

Non equilibrium anisotropic excitons in atomically thin ReS$_2$

J. M. Urban·M. Baranowski·A. Kuc·L. Klopotowski·A. Surrente·Y. Ma·D. Wlodarczyk·A. Suchocki·D. Ovchinnikov·T. Heine·D. K. Maude·A. Kis·P. Plochocka
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Abstract

We present a systematic investigation of the electronic properties of bulk and few layer ReS$_2$ van der Waals crystals using low temperature optical spectroscopy. Weak photoluminescence emission is observed from two non-degenerate band edge excitonic transitions separated by $\sim$ 20 meV. The comparable emission intensity of both excitonic transitions is incompatible with a fully thermalized (Boltzmann) distribution of excitons, indicating the hot nature of the emission. While DFT calculations predict bilayer ReS$_2$ to have a direct fundamental band gap, our optical data suggests that the fundamental gap is indirect in all cases.

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J. M. Urban, M. Baranowski, A. Kuc, L. Klopotowski, A. Surrente, Y. Ma, D. Wlodarczyk, A. Suchocki, D. Ovchinnikov, T. Heine, D. K. Maude, A. Kis, P. Plochocka. 2018-11-08. Non equilibrium anisotropic excitons in atomically thin ReS$_2$. https://doi.org/10.1088/2053-1583%2Faae9b9

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