  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.
