Strongly enhanced superconductivity in doped monolayer MoS2 by strain

The effects of strain on the stability, electron-phonon coupling, and superconductivity of doped monolayer MoS2 are investigated systematically using first-principles calculations. We find that most of the electron-phonon coupling in doped monolayer MoS2 is attributed to the in-plane vibrations of Mo atoms, which can be further tuned by strain. By applying biaxial compressive strain, we find a large enhancement in the superconducting transition temperature (T-c) and we obtain a T-c of 22 K at the optimal hole doping concentration, while the electron-phonon coupling of electron-doped structure is reduced due to the direct-indirect band-gap insulator transition. Our results reveal that the Fermi surface nesting-driven mechanism is mainly responsible for phonon softening and superconductivity in monolayer MoS2, suggesting that doping combined with strain is efficient at tuning electron-phonon coupling and superconductivity.