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Excitons in bulk black phosphorus evidenced by photoluminescence at low temperature

Abstract : Atomic layers of Black Phosphorus (BP) present unique opto-electronic properties dominated by a direct tunable bandgap in a wide spectral range from visible to mid-infrared. In this work, we investigate the infrared photoluminescence of BP single crystals at very low temperature. Near-bandedge recombinations are observed at 2 K, including dominant excitonic transitions at 0.276 eV and a weaker one at 0.278 eV. The free-exciton binding energy is calculated with an anisotropic Wannier-Mott model and found equal to 9.1 meV. On the contrary, the PL intensity quenching of the 0.276 eV peak at high temperature is found with a much smaller activation energy, attributed to the localization of free excitons on a shallow impurity. This analysis leads us to attribute respectively the 0.276 eV and 0.278 eV PL lines to bound excitons and free excitons in BP. As a result, the value of bulk BP bandgap is refined to 0.287 eV at 2K.
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Contributor : Étienne Gaufrès Connect in order to contact the contributor
Submitted on : Wednesday, December 9, 2020 - 8:40:30 PM
Last modification on : Friday, January 7, 2022 - 11:16:01 AM
Long-term archiving on: : Wednesday, March 10, 2021 - 8:11:19 PM


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E Carré, L Sponza, A Lusson, I Stenger, Étienne Gaufrès, et al.. Excitons in bulk black phosphorus evidenced by photoluminescence at low temperature. 2D Materials, IOP Publishing, 2021, 8 (2), pp.021001. ⟨10.1088/2053-1583/abca81⟩. ⟨hal-03049496⟩



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