Anisotropic carrier mobility of distorted Dirac cones: theory and application

TL;DR

This paper develops a theoretical model for intrinsic carrier mobility in semimetals with tilted Dirac cones, revealing how tilting affects mobility and applying it to borophene variants, predicting high mobilities at room temperature.

Contribution

It provides an analytic formula for carrier mobility in tilted Dirac cone semimetals and applies it to specific borophene materials, highlighting the impact of tilting and material properties.

Findings

Tilting significantly reduces carrier mobility.

Predicted high mobility in 8B-Pmmn borophene exceeds graphene.

Borophane has lower mobility due to smaller elastic constant.

Abstract

We have theoretically investigated the intrinsic carrier mobility in semimetals with distorted Dirac cones under both longitudinal and transverse acoustic phonon scattering. An analytic formula for the carrier mobility was obtained. It shows that tilting significantly reduces the mobility. The theory was then applied to 8B-Pmmn borophene and borophane (fully hydrogenated borophene), both of which have tilted Dirac cones. The predicted carrier mobilities in 8B-Pmmn borophene at room temperature are both higher than that in graphene. For borophane, despite its superhigh Fermi velocity, the carrier mobility is lower than that in 8B-Pmmn owing to its smaller elastic constant under shear strain.