First-principles study of the phonon-limited mobility in n-type single-layer MoS2

TL;DR

This study uses first-principles calculations to determine the phonon-limited electron mobility in n-type single-layer MoS2, revealing optical phonon scattering as the dominant factor and how gating conditions influence mobility.

Contribution

The paper provides the first-principles determination of electron-phonon interactions and mobility in single-layer MoS2, highlighting the impact of optical phonons and dielectric environment.

Findings

Room-temperature mobility ~410 cm^2 V^-1 s^-1 dominated by optical phonons.

Mobility follows a T^-1 dependence with an exponent of 1.69 at room temperature.

Quenching the homopolar mode increases mobility and reduces the temperature exponent.

Abstract

In the present work we calculate the phonon-limited mobility in intrinsic n-type single-layer MoS2 as a function of carrier density and temperature for T > 100 K. Using a first-principles approach for the calculation of the electron-phonon interaction, the deformation potentials and Fr\"ohlich interaction in the isolated MoS2 layer are determined. We find that the calculated room-temperature mobility of ~410 cm^2 V^-1 s^-1 is dominated by optical phonon scattering via deformation potential couplings and the Fr\"ohlich interaction with the deformation potentials to the intravalley homopolar and intervalley longitudinal optical phonons given by 4.1 x 10^8 eV/cm and 2.6 x 10^8 eV/cm, respectively. The mobility is weakly dependent on the carrier density and follows a \mu ~ T^-1 temperature dependence with \gamma = 1.69 at room temperature. It is shown that a quenching of the characteristic homopolar mode which is likely to occur in top-gated samples, boosts the mobility with 70 cm^2 V^-1 s^-1 and can be observed as a decrease in the exponent to \gamma = 1.52. Our findings indicate that the intrinsic phonon-limited mobility is approached in samples where a high-kappa dielectric that effectively screens charge impurities is used as gate oxide.