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arXiv · 2306.10812

Trion photoluminescence and trion stability in atomically thin semiconductors

Raul Perea-Causin·Samuel Brem·Ole Schmidt·Ermin Malic
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Abstract

The optical response of doped monolayer semiconductors is governed by trions, i.e. photoexcited electron-hole pairs bound to doping charges. While their photoluminescence (PL) signatures have been identified in experiments, a microscopic model consistently capturing bright and dark trion peaks is still lacking. In this work, we derive a generalized trion PL formula on a quantum-mechanical footing, considering direct and phonon-assisted recombination mechanisms. We show the trion energy landscape in WSe$_2$ by solving the trion Schr\"odinger equation. We reveal that the mass imbalance between equal charges results in less stable trions exhibiting a small binding energy and, interestingly, a large energetic offset from exciton peaks in PL spectra. Furthermore, we compute the temperature-dependent PL spectra for n- and p-doped monolayers and predict yet unobserved signatures originating from trions with an electron at the $\Lambda$ point. Our work presents an important step towards a microscopic understanding of the internal structure of trions determining their stability and optical fingerprint.

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Raul Perea-Causin, Samuel Brem, Ole Schmidt, Ermin Malic. 2023-06-19. Trion photoluminescence and trion stability in atomically thin semiconductors. https://doi.org/10.1103/physrevlett.132.036903

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