Experimental demonstration of two distinct pathways of trion generation in monolayer MoS2

Faiha Mujeeb; Arkaprava Chowdhury; Anindya Datta; Subhabrata Dhar

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arXiv · 2508.17584

Experimental demonstration of two distinct pathways of trion generation in monolayer MoS2

Faiha Mujeeb·Arkaprava Chowdhury·Anindya Datta·Subhabrata Dhar

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Abstract

Excitation power and energy dependent photoluminescence (PL) and transient absorption spectroscopy (TAS) studies are carried out on chemical vapour deposition (CVD) grown 1L-MoS2 films to understand the process of trion formation. The study shows that the excitation with sufficiently low photon energy results in the creation of trions directly in the K/K' valleys through photon absorption followed by phonon scattering events. On the other hand, excitation energy sufficiently larger than the band-gap can generate the carriers away from the K/K' valleys. Dissimilarity in the rates of relaxation of the photo-excited electrons and the holes to the bottom of the K/K' valleys results in the transformation of the excitons residing there into trions. Our TAS study clearly demonstrates a temporary increase of the trion population in the K/K' valleys. Moreover, excitation intensity dependent PL spectroscopy performed under above-band-gap excitation, also suggests the coexistence of both the pathways of trion generation in this material. This conclusion is further validated by a rate equation model. Our findings provide valuable insight into the formation of trions in monolayer transition metal dichalcogenides (TMDC), which could be crucial in designing valleytronic devices based on trions.

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Faiha Mujeeb, Arkaprava Chowdhury, Anindya Datta, Subhabrata Dhar. 2025-08-25. Experimental demonstration of two distinct pathways of trion generation in monolayer MoS2. https://arxiv.org/abs/2508.17584

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