Effect of substrate screening on the electronic structure of monolayer MoS2

Monolayers of transition-metal dichalcogenides (TMD) hold great promise as future nanoelectronic and optoelectronic devices. An essential feature for achieving high device performance is the use of suitable supporting substrates, which can strongly affect the electronic and optical properties of these two-dimensional (2D) materials. Here, we investigate the effect of substrate screening on the quasiparticle band structure of monolayer MoS2 by performing many-body GW calculations with an effective dielectric screening. We show that the substrate can have a significant effect on the quasiparticle band gap, for example the gap renormalization is as large as 250 meV for MoS2 on SiO2. Within the G0W0 approximation, we find that the supported monolayer exhibits a direct band gap, in contrast to the free-standing monolayer. We also find that substrate screening induces an enhancement of the carrier effective masses by as much as 27% for holes, shifts plasmon satellites, and redistributes quasiparticle weight. Our results highlight the importance of the dielectric environment in the design of 2D TMD-based devices.