Intrinsic transport properties of electrons and holes in monolayer transition-metal dichalcogenides

Intrinsic electron-and hole-phonon interactions are investigated in monolayer transition-metal dichalcogenides MX2 (M=Mo, W; X=S, Se) based on a density functional theory formalism. Due to their structural similarities, all four materials exhibit qualitatively comparable scattering characteristics with the acoustic phonons playing a dominant role near the conduction and valence band extrema at the K point. However, substantial differences are observed quantitatively leading to disparate results in the transport properties. Of those considered, WS2 provides the best performance for both electrons and holes with high mobilities and saturation velocities in the full-band Monte Carlo analysis of the Boltzmann transport equation. It is also found that monolayer MX2 crystals with an exception of MoSe2 generally show hole mobilities comparable to or even larger than the value for bulk silicon at room temperature, suggesting a potential opportunity in p-type devices. The analysis is extended to estimate the effective deformation potential constants for a simplified treatment as well.