Transient optical reflectivity in MoSe₂ under 785 nm and 810 nm pump excitation

Authors

Semmi Takamizawa Graduate School of Pure and Applied Sciences, University of Tsukuba, Japan
Yuta Komori Graduate School of Pure and Applied Sciences, University of Tsukuba, Japan
Takumi Fukuda Graduate School of Pure and Applied Sciences, University of Tsukuba, Japan
Manaka Kawamura Graduate School of Science and Engineering, Saitama University, Japan
Keiji Ueno Graduate School of Science and Engineering, Saitama University, Japan
Muneaki Hase Faculty of Pure and Applied Sciences, University of Tsukuba, Japan
Jessica Afalla Faculty of Pure and Applied Sciences, University of Tsukuba, Japan

Abstract

Transition-metal dichalcogenide (TMDC) crystals have emerged as a new class of two-dimensional materials. TMDCs exhibit strong Coulomb interaction (E_B=50−500 meV), and at monolayer thicknesses, can exibit exotic valley- and spin- dependent optical selection rules. The TMDC MoSe₂ is semiconducting at room temperature, with a bulk bandgap of ~1.10 eV, and forms ground state A-excitons at its K-point (~1.6 eV). In this report, we present transient reflectivity measurements at 785 nm (1.57 eV) and 810 nm (1.53 eV) optical excitation of bulk MoSe₂. A signal inversion of the optical reflectivity was observed with wavelength. When excited near-resonance, the transient reflectivity shows no dependence on fluence and decay times are observed to be longer than the non-resonant case. When excited non-resonantly, a clear fluence dependence is observed in the excitation and decay dynamics. The difference is attributed to the possible formation of A-excitons.

Downloads

Issue

2021: Proceedings of the 39th Samahang Pisika ng Pilipinas Physics Conference

Article ID

SPP-2021-2F-02

Section

Condensed Matter Physics and Materials Science

Published

2021-09-24

How to Cite

[1]

S Takamizawa, Y Komori, T Fukuda, M Kawamura, K Ueno, M Hase, and J Afalla, Transient optical reflectivity in MoSe2 under 785 nm and 810 nm pump excitation, Proceedings of the Samahang Pisika ng Pilipinas 39, SPP-2021-2F-02 (2021). URL: https://proceedings.spp-online.org/article/view/SPP-2021-2F-02.