Spectroscopy of Van der Waals structures based on the transition metal dichalcogenide WS$_2$

D. D. Belova^ab, T. E. Zedomi^a, L. V. Kotova^ab, V. P. Kochereshko<sup>a

a</sup> Ioffe Institute, St. Petersburg
^b Baltic State Technical University, St. Petersburg

Abstract: The low-temperature photoluminescence and light reflection spectra of thin layers (down to monolayers) of WS$_2$ on oxidised silicon substrates were investigated. A rich interference structure was observed in the reflection spectra. By comparing the reflection spectra from the SiO$_2$/Si substrate and from WS$_2$ using the known refractive index, the thicknesses of these layers were determined. It was found that most of the lines in the reflection spectra are associated with the Si/SiO$_2$ layer. A series of lines previously attributed to the ground and excited states of the exciton were observed in the photoluminescence and reflection spectra from WS$_2$. It was established that these lines are associated with light interference near the exciton resonance in WS$_2$ at an energy of 2.15 eV.

Keywords: spectroscopy, transition metal dichalcogenides, excitons.

Received: 13.12.2024
Revised: 03.04.2025
Accepted: 08.04.2025

DOI: 10.61011/PJTF.2025.13.60704.20224