Strong mobility degradation in ideal graphene nanoribbons due to phonon scattering

TL;DR

This study analyzes phonon-limited mobility in armchair graphene nanoribbons, revealing significant mobility degradation due to confinement and substrate effects, with implications for nanoelectronic device performance.

Contribution

It provides a comprehensive calculation of phonon-limited mobility in GNRs using full-band dispersion, highlighting the impact of confinement and substrate interactions on mobility.

Findings

Mobility in GNRs is much lower than in 2D graphene.

Surface phonons further reduce mobility on HfO2 substrates.

Polaron formation causes band gap renormalization of ~118 meV.

Abstract

We investigate the low-field phonon-limited mobility in armchair graphene nanoribbons (GNRs) using full-band electron and phonon dispersion relations. We show that lateral confinement suppresses the intrinsic mobility of GNRs to values typical of common bulk semiconductors, and very far from the impressive experiments on 2D graphene. Suspended GNRs with a width of 1 nm exhibit a mobility close to 500 cm^2/Vs at room temperature, whereas if the same GNRs are deposited on HfO2 mobility is further reduced to about 60 cm^2/Vs due to surface phonons. We also show the occurrence of polaron formation, leading to band gap renormalization of ~118 meV for 1 nm-wide armchair GNRs.