Resonant Raman and photoluminescence spectra of suspended molybdenum disulfide

TL;DR

This study compares the Raman and photoluminescence spectra of suspended and supported MoS2, revealing minimal spectral differences due to dielectric environment but notable variations in peak intensities and resonance effects.

Contribution

It provides detailed spectral analysis of suspended versus supported MoS2, highlighting the influence of dielectric environment and resonance on vibrational modes.

Findings

Interference effects explain most PL intensity differences.

Raman peak positions are similar between suspended and supported samples.

Resonance enhances inter-layer vibration modes, especially breathing modes.

Abstract

Raman and photoluminescence (PL) measurements were performed on suspended and supported MoS2 up to 6 trilayers (TLs). The difference in the dielectric environment of suspended and supported MoS2 does not lead to large differences in the PL or Raman spectra. Most of the apparent difference in the PL intensity can be explained by the interference effect except for 1TL MoS2. The positions of the Raman peaks are not much different between suspended and supported MoS2. The relative intensities, on the other hand, show some differences between suspended and supported samples. In particular, the inter-layer vibration modes are enhanced near resonance with C excitons, with the breathing modes becoming relatively stronger. Up to 4 breathing modes are resolved in suspended 6TL MoS2.