Intrinsic electronic transport and thermoelectric power factor in n-type doped monolayer MoS2

Abstract

The electronic transport and thermoelectric properties in n-type doped monolayer MoS2 are investigated by a parameter-free method based on first-principles calculations, electron–phonon coupling (EPC), and Boltzmann transport equation (BTE). Remarkably, the calculated electron mobility μ ∼ 47 cm2 V−1s−1 and thermoelectric power factor σS2 ∼ 2.93 × 10−3 W m−1 K−2 at room temperature are much lower than the previous theoretical values (e.g. μ ∼ 130–410 cm2 V−1 s−1 and σS2 ∼ 2.80 × 10−2 W m−1 K−2), but agree well with the most recent experimental findings of μ ∼ 37 cm2 V−1 s−1 and σS2 ∼ 3.00 × 10−3 W m−1 K−2. The EPC projections on phonon dispersion and the phonon branch dependent scattering rates indicate that the acoustic phonons, especially the longitudinal acoustic phonons, dominate the carrier scattering. Therefore, a mobility of 68 cm2 V−1 s−1 is achieved if only the acoustic phonons induced scattering is included, in accordance with the result of 72 cm2 V−1 s−1 estimated from the deformation potential driven by acoustic modes. Furthermore, via excluding the scattering from the out-of-plane modes to simulate the EPC suppression, the obtained mobility of 258 cm2 V−1 s−1 is right in the range of 200–700 cm2 V−1 s−1 measured in the samples with top deposited dielectric layer. In addition, we also compute the lattice thermal conductivity κL of monolayer MoS2 using phonon BTE, and obtain a κL ∼ 123 W m−1 K−1 at 300 K.