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arXiv · 2010.15449

Excitons in bulk black phosphorus evidenced by photoluminescence at low temperature

Etienne Carré·Lorenzo Sponza·Alain Lusson·Ingrid Stenger·Etienne Gaufrès·Annick Loiseau·Julien Barjon
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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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Etienne Carré, Lorenzo Sponza, Alain Lusson, Ingrid Stenger, Etienne Gaufrès, Annick Loiseau, Julien Barjon. 2020-10-29. Excitons in bulk black phosphorus evidenced by photoluminescence at low temperature. https://doi.org/10.1088/2053-1583/abca81

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