Layer-Dependent Vibrational and Optical Properties of Mo0.58W0.42Se2 Alloy
Abstract
Semiconducting MoxW1−xSe2 alloys provide a versatile platform for tailoring the optical properties of two-dimensional materials through both composition and layer thickness. Here, we systematically investigate mechanically exfoliated Mo0.58W0.42Se2 flakes ranging from monolayer (1L) to nine layers by combining Raman scattering (RS), photoluminescence (PL), reflectance contrast (RC) spectroscopy, and first-principles phonon calculations. Thirteen RS peaks are identified, including the low-frequency interlayer shear mode, whose thickness dependence is well described by a linear-chain model, yielding an interlayer force constant of Ks=(2.996±0.015)×1019 N m−3. PL measurements reveal a crossover from the direct-bandgap 1L to indirect-bandgap multilayers. The thickness evolution of the indirect optical transition is quantitatively reproduced using a quantum-confinement model, yielding an out-of-plane reduced effective mass of μ⊥=0.75 m0. RC spectroscopy reveals four excitonic resonances. While the A and B excitons associated with the K± valleys remain nearly independent of layer thickness, the higher-energy C and D resonances originating from the band-nesting regions exhibit pronounced redshifts, reflecting substantial thickness-induced modifications of the electronic band structure. These results establish comprehensive spectroscopic fingerprints of flake thickness, interlayer coupling, and electronic structure in MoxW1−xSe2 alloys and provide a reliable, non-destructive framework for their optical characterization.
Related
- First-principles investigation of structural, mechanical, vibrational, thermal, electronic and optical properties of Na3Bi: a topological Dirac semimetal
- Layer-Dependent Phonons, Excitons, and Magneto-Optical Phenomena in CrSBr: A Mini Review
- Nonperturbative theory of thin-vapor-layer linear optical properties: towards the optimal design of alkali-metal vapor nanocells
- Computing binary alloy phase diagrams with explicit configurational and vibrational entropy
- Capturing attosecond delays in electronic and vibrational dependent photoemission of NO molecules
BibTeX
@misc{socha2026layerdependent,
title = {{Layer-Dependent Vibrational and Optical Properties of $\mathrmMo0.58\mathrmW0.42\mathrmSe_2$ Alloy}},
author = {Szymon Socha and Tomasz Wozniak and Elena Blundo and Malgorzata Brzoska and Grzegorz Krasucki and Piotr Wrobel and Antonio Polimeni and Adam Babinski and Maciej R. Molas and Katarzyna Olkowska-Pucko},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.18572},
eprint = {2609.18572},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.18572},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Layer-Dependent Vibrational and Optical Properties of Mo0.58W0.42Se_2 Alloy
AU - Szymon Socha
AU - Tomasz Wozniak
AU - Elena Blundo
AU - Malgorzata Brzoska
AU - Grzegorz Krasucki
AU - Piotr Wrobel
AU - Antonio Polimeni
AU - Adam Babinski
AU - Maciej R. Molas
AU - Katarzyna Olkowska-Pucko
PY - 2026
DA - 2026/09/16
PB - arXiv
DO - 10.48550/arxiv.2609.18572
UR - https://arxiv.org/abs/2609.18572
AB - Semiconducting Mo_xW_1−xSe_2 alloys provide a versatile platform for tailoring the optical properties of two-dimensional materials through both composition and layer thickness. Here, we systematically investigate mechanically exfoliated Mo_0.58W_0.42Se_2 flakes ranging from monolayer (1L) to nine layers by combining Raman scattering (RS), photoluminescence (PL), reflectance contrast (RC) spectroscopy, and first-principles phonon calculations. Thirteen RS peaks are identified, including the low-frequency interlayer shear mode, whose thickness dependence is well described by a linear-chain model, yielding an interlayer force constant of K_s=(2.996±0.015)×10^19 N m^−3. PL measurements reveal a crossover from the direct-bandgap 1L to indirect-bandgap multilayers. The thickness evolution of the indirect optical transition is quantitatively reproduced using a quantum-confinement model, yielding an out-of-plane reduced effective mass of μ_⊥=0.75 m_0. RC spectroscopy reveals four excitonic resonances. While the A and B excitons associated with the K^± valleys remain nearly independent of layer thickness, the higher-energy C and D resonances originating from the band-nesting regions exhibit pronounced redshifts, reflecting substantial thickness-induced modifications of the electronic band structure. These results establish comprehensive spectroscopic fingerprints of flake thickness, interlayer coupling, and electronic structure in Mo_xW_1−xSe_2 alloys and provide a reliable, non-destructive framework for their optical characterization.
ER -