Intrinsic Electrical Transport Properties of Monolayer Silicene and MoS2 from First Principles

TL;DR

This study uses first-principles calculations to analyze electron-phonon interactions and transport properties in monolayer silicene and MoS2, revealing key phonon modes affecting electron mobility and the influence of intervalley scattering.

Contribution

It provides a detailed first-principles analysis of intrinsic electron-phonon interactions and transport properties in silicene and MoS2, highlighting the roles of specific phonon modes and intervalley scattering.

Findings

Out-of-plane acoustic phonons dominate in silicene, degrading electron transport.

Longitudinal acoustic phonons are significant in MoS2, with Q valleys affecting scattering.

Extrinsic screening can significantly reduce scattering rates.

Abstract

The electron-phonon interaction and related transport properties are investigated in monolayer silicene and MoS2 by using a density functional theory calculation combined with a full-band Monte Carlo analysis. In the case of silicene, the results illustrate that the out-of-plane acoustic phonon mode may play the dominant role unlike its close relative - graphene. The small energy of this phonon mode, originating from the weak sp2 bonding between Si atoms, contributes to the high scattering rate and significant degradation in electron transport. In MoS2, the longitudinal acoustic phonons show the strongest interaction with electrons. The key factor in this material appears to be the Q valleys located between the {\Gamma} and K points in the first Brillouin zone as they introduce additional intervalley scattering. The analysis also reveals the potential impact of extrinsic screening by other carriers and/or adjacent materials. Subsequent decrease in the actual scattering rate can be drastic, warranting careful consideration. Finally, the effective deformation potential constants are extracted for all relevant intrinsic electron-phonon scattering processes in both materials.