Optical spectroscopy of excitons in ReS2 monolayers grown by chemical vapor deposition

TL;DR

This study investigates the optical properties of ReS2 monolayers grown via chemical vapor deposition, revealing excitonic features through Raman, photoluminescence, and absorbance spectroscopies, supported by theoretical calculations.

Contribution

It provides detailed experimental and theoretical analysis of excitonic behavior in CVD-grown ReS2 monolayers, including identification of specific excitonic peaks.

Findings

Identification of multiple phonon modes confirmed by DFT calculations.

Observation of a sharp PL line at 1.2620 eV indicating excitonic transition.

Detection of an exciton peak around 1.4660 eV in absorbance spectrum.

Abstract

Monolayers of ReS2 were grown by a chemical vapor deposition technique on SiO2/Si substrates and investigated at room temperature by using micro-Raman, micro-photoluminescence (PL) and absorbance spectroscopies. The Raman scattering spectrum exhibits several phonon modes that were confirmed by the computation analysis based on the density functional theory. The ReS2 structural integrity was confirmed by using the XRD and the energy dispersion spectroscopy that was obtained by the scanning electron microscopy. Photoluminescence spectra show excitons related to interband transition in thin monolayer flakes and bulk-like structures. Additionally, a sharp PL line located at 1.2620 eV with a second harmonic peak at 2.5420 eV were observed and explained in terms of interband excitonic transitions originated within the rhenium 5d orbit. An optical absorbance spectrum with an exciton peak around 1.4660 eV was obtained for an assembly of ReS2 flakes grown on silica substrate.