The effect of the substrate on the Raman and photoluminescence emission of single layer MoS2

TL;DR

This study investigates how different substrates influence the Raman and photoluminescence emissions of single-layer MoS2, revealing substrate-induced effects on emission intensities, spectral positions, and excitonic properties.

Contribution

It provides a quantitative analysis of substrate effects on MoS2 emissions and introduces a method for tuning PL emission via substrate selection.

Findings

Substrate affects emission intensities through interference effects.

Spectral positions of Raman and PL features are substrate-dependent.

Substrate-induced doping alters excitonic decay rates.

Abstract

We quantitatively study the Raman and photoluminescence (PL) emission from single layer molybdenum disulfide (MoS2) on dielectric (SiO2, hexagonal boron nitride, mica and the polymeric dielectric Gel-Film) and conducting substrates (Au and few-layer graphene). We find that the substrate can affect the Raman and PL emission in a twofold manner. First, the absorption and emission intensities are strongly modulated by the constructive/destructive interference within the different substrates. Second, the position of the A1g Raman mode peak and the spectral weight between neutral and charged excitons in the PL spectra are modified by the substrate. We attribute this effect to substrate-induced changes in the doping level and in the decay rates of the excitonic transitions. Our results provide a method to quantitatively study the Raman and PL emission from MoS2-based vertical heterostructures and represent the first step in ad-hoc tuning the PL emission of 1L MoS2 by selecting the proper substrate.