Dynamics of exciton formation, recombination, and trapping in monolayers of 2D-TMD materials

Joie M. Yuson; Dillon Contreras; Marina Achterman; Edward Jung; Abdelaziz Boulesbaa

doi:10.1117/12.2630804

4 March 2022 Dynamics of exciton formation, recombination, and trapping in monolayers of 2D-TMD materials

Joie M. Yuson, Dillon Contreras, Marina Achterman, Edward Jung, Abdelaziz Boulesbaa

Proceedings Volume 11990, Nanoscale and Quantum Materials: From Synthesis and Laser Processing to Applications 2022; 1199005 (2022) https://doi.org/10.1117/12.2630804
Event: SPIE LASE, 2022, San Francisco, California, United States

Abstract

The optical and electrical properties of two-dimensional transition metal dichalcogenide materials (2D-TMDs) are determined by their exciton dynamics. When the thickness of these materials is thinned down to a single layer, the spatial confinement makes the impact of exciton dynamics on the functionality of 2D-TMD-based devices even more important. Here, we present an investigation of the dynamics of formation and decay of the lowest excitons 2D-TMD monolayers. Excitation energy-dependent transient absorption studies indicated that the exciton formation time increases linearly from ~150 fs upon resonant excitation to ~500 fs following excitation that is ~1.1 eV above the bandgap. This dependence is attributed to the time it takes highly excited electrons in the conduction band (CB) to relax to the CB minimum (CBM) and contribute to the formation of the X_A exciton. Additionally, excitation energy dependent studies suggested that the exciton average lifetime increases from ~10 ps in the case of resonant excitation to ~50 ps following excitation well above the band-gap. Furthermore, studies of the dependence of exciton dynamics on the excitation density suggested that exciton decay in these materials is dominated by defect-assisted recombination (DAR).

Conference Presentation

Citation Download Citation

Joie M. Yuson, Dillon Contreras, Marina Achterman, Edward Jung, and Abdelaziz Boulesbaa "Dynamics of exciton formation, recombination, and trapping in monolayers of 2D-TMD materials", Proc. SPIE 11990, Nanoscale and Quantum Materials: From Synthesis and Laser Processing to Applications 2022, 1199005 (4 March 2022); https://doi.org/10.1117/12.2630804

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