Exciton-Phonon Interactions in Strained Domes of Monolayer MoS2 Studied by Resonance Raman Spectroscopy

Jessica S Lemos; Elena Blundo; Antonio Polimeni; Marcos A Pimenta; Ariete Righi

doi:10.3390/nano13192722

Exciton-Phonon Interactions in Strained Domes of Monolayer MoS₂ Studied by Resonance Raman Spectroscopy

Nanomaterials (Basel). 2023 Oct 7;13(19):2722. doi: 10.3390/nano13192722.

Authors

Jessica S Lemos¹, Elena Blundo², Antonio Polimeni², Marcos A Pimenta^{1

3}, Ariete Righi¹

Affiliations

¹ Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, MG, Brazil.
² Dipartimento di Fisica, Sapienza Università di Roma, 00185 Roma, Italy.
³ Departamento de Física, Universidade Federal do Ouro Preto, Campus Universitário Morro do Cruzeiro, ICEB, Ouro Preto 35400-000, MG, Brazil.

Abstract

This work describes a resonance Raman study performed in the domes of monolayer MoS₂ using 23 different laser excitation energies covering the visible and near-infrared (NIR) ranges. The multiple excitation results allowed us to investigate the exciton-phonon interactions of different phonons (A'₁, E', and LA) with different excitonic optical transitions in biaxially strained monolayer MoS2. The analysis of the intensities of the two first-order peaks, A'₁ and E', and the double-resonance 2LA Raman band as a function of the laser excitation furnished the values of the energies of the indirect exciton and the direct excitonic transitions in the strained MoS2 domes. It was noticed that the out-of-plane A'₁ phonon mode is significantly enhanced only by the indirect exciton I and the C exciton, whereas the in-plane E' mode is only enhanced by the C exciton of the MoS₂ dome, thus revealing the weak interaction of these phonons with the A and B excitons in the strained MoS2 domes. On the other hand, the 2LA Raman band is significantly enhanced at the indirect exciton I and by the A (or B) exciton but not enhanced by the C exciton, thus showing that the LA edge phonons that participate in the double-resonance process in MoS2 have a weak interaction with the C exciton.

Keywords: MoS2 dome; Raman excitation profile; biaxial strain.

Grants and funding

We gratefully acknowledge the financial support provided by the following Brazilian institutions: Instituto Nacional de Ciência e Tecnologia (INCT) em Nanomateriais de Carbono, Financiadora de Estudos e Projetos (FINEP), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), and Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG). Without their support, this work would not have been possible. This project was partly funded within the QuantERA II Programme that has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 101017733, and with funding organisations Ministero dell’Universitá e della Ricerca (MUR) and Consiglio Nazionale delle Ricerche (CNR). We acknowledge financial support from the PNRR MUR project PE0000023-NQSTI.