Phonon-limited Mobility of 2D Semiconductors: Quadrupole Scattering and Free-carrier Screening

TL;DR

This paper introduces a first-principles method that incorporates quadrupole scattering and free-carrier screening to accurately calculate phonon-limited mobility in 2D semiconductors like MoS2 and InSe, enhancing understanding of their transport properties.

Contribution

The authors develop a novel first-principles approach that includes quadrupole scattering and free-carrier screening, improving mobility predictions in 2D semiconductors.

Findings

InSe mobility is highly sensitive to carrier concentration.

Mobility of InSe can increase up to four times with doping.

The new method yields more accurate mobility calculations.

Abstract

Two-dimensional (2D) semiconductors have demonstrated great potential for next-generation electronics and optoelectronics. An important property for these applications is the phonon-limited charge carrier mobility. The common approach to calculate the mobility from first principles relies on the interpolation of the electron-phonon coupling (EPC) matrix. However, it neglects the scattering by the dynamical quadrupoles generated by phonons, limiting its accuracy. Here we present a first-principles method to incorporate the quadrupole scattering, which results in a much better interpolation quality and thus a more accurate mobility as exemplified by monolayer MoS2 and InSe. This method also allows for a natural incorporation of the effects of the free carriers, enabling us to efficiently compute the screened EPC and thus the mobility for doped semiconductors. Particularly, we find that the electron mobility of InSe is more sensitive to the carrier concentration than that of MoS2 due to the stronger long-range scattering in intrinsic InSe. With increasing electron concentration, the InSe mobility can reach ~4 times of the intrinsic value, then decrease owing to the involvement of heavier electronic states. Our work provides accurate and efficient methods to calculate the phonon-limited mobility in the intrinsic and doped 2D materials, and improves the fundamental understanding of their transport mechanism.