Acoustic phonon limited mobility in two-dimensional semiconductors: Deformation potential and piezoelectric scattering in monolayer MoS2 from first principles

TL;DR

This study provides a detailed theoretical analysis of acoustic phonon limited mobility in monolayer MoS2, highlighting the roles of deformation potential and piezoelectric scattering, and predicting high intrinsic mobilities at low temperatures.

Contribution

First-principles calculations combined with analytical models reveal the impact of deformation potential and piezoelectric interactions on mobility in monolayer MoS2, including the effects of carrier screening.

Findings

Mobility transitions from T^{-1} to T^{-4} behavior at low temperatures.

Predicted intrinsic mobility exceeds 10^5 cm^2 V^{-1} s^{-1} below 10 K.

Mobility at 100 K is limited to about 7,000 cm^2 V^{-1} s^{-1}.

Abstract

We theoretically study the acoustic phonon limited mobility in n-doped two-dimensional MoS2 for temperatures T < 100 K and high carrier densities using the Boltzmann equation and first-principles calculations of the acoustic electron-phonon (el-ph) interaction. In combination with a continuum elastic model, analytic expressions and the coupling strengths for the deformation potential and piezoelectric interactions are established. We furthermore show that the deformation potential interaction has contributions from both normal and umklapp processes and that the latter contribution is only weakly affected by carrier screening. Consequently, the calculated mobilities show a transition from a high-temperature \mu T^{-1} behavior to a stronger \mu T^{-4} behavior in the low-temperature Bloch-Gruneisen regime characteristic of unscreened deformation potential scattering. Intrinsic mobilities in excess of 10^5 cm^2 V^{-1} s^{-1} are predicted at T < 10 K and high carrier densities (n > 10^{11} cm^{-2}). At 100 K, the mobility does not exceed ~7 x 10^3 cm2 V^{-1} s^{-1}. Our findings provide new and important understanding of the acoustic el-ph interaction and its screening by free carriers, and is of high relevance for the understanding of acoustic phonon limited mobilities in general.