Alloy engineering of excitonic properties in TMD monolayers
Abstract
We investigate monolayer MoS2xSe2(1−x) alloys across the full composition range using optical spectroscopy. We demonstrate continuous tuning of the optical gap over ∼0.35 eV, accompanied by a systematic reduction of the B--A exciton splitting, in agreement with density functional theory calculations. Temperature-dependent measurements reveal a progressive increase of the average phonon energy from Se-rich to S-rich alloys that follows a simple reduced-mass scaling model. Polarization-resolved spectroscopy further shows a monotonic increase of the circular polarization from nearly zero in MoSe2 to ∼15\% in MoS2 at 78 K. The observed evolution of the polarization is attributed to alloy-induced modifications of the electronic structure that modify bright--dark exciton mixing and the associated valley depolarization. These findings establish alloy engineering as an effective strategy for controlling excitonic properties in TMD monolayers.
Versions
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BibTeX
@misc{katsipoulaki2026alloy,
title = {{Alloy engineering of excitonic properties in TMD monolayers}},
author = {Eirini Katsipoulaki and Adlen Smiri and Panagiotis Spiliotakis and Konstantinos Mourzidis and Danae Katrisioti and Takashi Taniguchi and Kenji Watanabe and Georgios Kopidakis and Zdenek Sofer and Gang Wang and Emmanuel Stratakis and George Kioseoglou and Iann C. Gerber and Xavier Marie and Ioannis Paradisanos},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.03347},
eprint = {2608.03347},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.03347},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Alloy engineering of excitonic properties in TMD monolayers
AU - Eirini Katsipoulaki
AU - Adlen Smiri
AU - Panagiotis Spiliotakis
AU - Konstantinos Mourzidis
AU - Danae Katrisioti
AU - Takashi Taniguchi
AU - Kenji Watanabe
AU - Georgios Kopidakis
AU - Zdenek Sofer
AU - Gang Wang
AU - Emmanuel Stratakis
AU - George Kioseoglou
AU - Iann C. Gerber
AU - Xavier Marie
AU - Ioannis Paradisanos
PY - 2026
DA - 2026/08/04
PB - arXiv
DO - 10.48550/arxiv.2608.03347
UR - https://arxiv.org/abs/2608.03347
AB - We investigate monolayer MoS_2xSe_2(1−x) alloys across the full composition range using optical spectroscopy. We demonstrate continuous tuning of the optical gap over ∼0.35 eV, accompanied by a systematic reduction of the B--A exciton splitting, in agreement with density functional theory calculations. Temperature-dependent measurements reveal a progressive increase of the average phonon energy from Se-rich to S-rich alloys that follows a simple reduced-mass scaling model. Polarization-resolved spectroscopy further shows a monotonic increase of the circular polarization from nearly zero in MoSe_2 to ∼15\% in MoS_2 at 78 K. The observed evolution of the polarization is attributed to alloy-induced modifications of the electronic structure that modify bright--dark exciton mixing and the associated valley depolarization. These findings establish alloy engineering as an effective strategy for controlling excitonic properties in TMD monolayers.
ER -