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The Fine-Structure Constant as a Ruler for the Band-Edge Light Absorption Strength of Bulk and Quantum-Confined Semiconductors

Abstract : Low-dimensional semiconductors have found numerous applications in optoelectronics. However, a quantitative comparison of the absorption strength of lowdimensional versus bulk semiconductors has remained elusive. Here, we report generality in the band-edge light absorptance of semiconductors, independent of their dimensions. First, we provide atomistic tight-binding calculations that show that the absorptance of semiconductor quantum wells equals mπα (m = 1 or 2 with α as the fine-structure constant), in agreement with reported experimental results. Then, we show experimentally that a monolayer (superlattice) of quantum dots has similar absorptance, suggesting an absorptance quantum of mπα per (confined) exciton diameter. Extending this idea to bulk semiconductors, we experimentally demonstrate that an absorptance quantum equal to mπα per exciton Bohr diameter explains their widely varying absorption coefficients. We thus provided compelling evidence that the absorptance quantum πα per exciton diameter rules the band-edge absorption of all direct semiconductors, regardless of their dimension.
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Contributor : Christophe Delerue Connect in order to contact the contributor
Submitted on : Tuesday, November 16, 2021 - 11:43:52 AM
Last modification on : Tuesday, April 26, 2022 - 4:06:04 PM
Long-term archiving on: : Thursday, February 17, 2022 - 6:39:01 PM


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P Prins, Maryam Alimoradi Jazi, Niall Killilea, Wiel Evers, Pieter Geiregat, et al.. The Fine-Structure Constant as a Ruler for the Band-Edge Light Absorption Strength of Bulk and Quantum-Confined Semiconductors. Nano Letters, American Chemical Society, 2021, 21 (22), pp.9426-9432. ⟨10.1021/acs.nanolett.1c02682⟩. ⟨hal-03430478⟩



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