Phonon and exciton temperature-dependent properties of twisted MoS$_2$

Francisco Silva-Santos; Ruben da Silva; Yuset Guerra Dávila; Maykol Oliveira; Zhuohang Yu; Mauricio Terrones; Antonio Souza Filho; Rafael Alencar; Bartolomeu Viana

arXiv · 2402.03272

Phonon and exciton temperature-dependent properties of twisted MoS$_2$

Francisco Silva-Santos·Ruben da Silva·Yuset Guerra Dávila·Maykol Oliveira·Zhuohang Yu·Mauricio Terrones·Antonio Souza Filho·Rafael Alencar·Bartolomeu Viana

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Abstract

In the present work, Raman and photoluminescence spectroscopies were used to study the dynamics of phonons and different excitons of MoS$_2$ bilayer under a rotation of 29$^{\circ}$ dependent of the temperature. The twisted bilayer (T-2L) of MoS$_2$ was obtained through mechanical exfoliation, and subsequently rotated using a dimethyl polysiloxane (PDMS) substrate and deterministic transferred to a SiO$_2$ substrate. The Raman spectrum of the twisted bilayer presents three peaks E$'$ (386 cm$^{-1}$), A$'_{1}$ (405 cm$^{-1}$) and an FA$'$ peak at approximately 409 cm$^{-1}$ linked to the A$'_{1}$ mode, which is attributed to a Moiré pattern phonon. Both modes (A$'_{1}$ and FA$'$) are dependent of light polarization in a way that demonstrates an effective coupling between the layers. It was also verified through the Grüneisen parameter, an increase in the anharmonicity of the mode in the E$'$ plane and a decrease the same for A$'_{1}$. In the PL measurements, the appearance of an exciton in T-2L was verified, which generated a second shoulder measured at $\approx$1.58 eV attributed to an indirect transition of an I trion. The interaction between the rotated monolayers of MoS$_{2}$ proved to be an important parameter for possible fine-tuning of the properties of bilayer samples.

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Francisco Silva-Santos, Ruben da Silva, Yuset Guerra Dávila, Maykol Oliveira, Zhuohang Yu, Mauricio Terrones, Antonio Souza Filho, Rafael Alencar, Bartolomeu Viana. 2024-02-05. Phonon and exciton temperature-dependent properties of twisted MoS$_2$. https://arxiv.org/abs/2402.03272

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