Mobility and Saturation Velocity in Graphene on SiO2

TL;DR

This study investigates how mobility and saturation velocity in graphene on SiO2 vary with temperature and carrier density, revealing that substrate effects limit performance but intrinsic properties could be higher.

Contribution

It provides a detailed analysis of mobility and saturation velocity in graphene on SiO2 at high temperatures and fields, incorporating practical models and highlighting substrate limitations.

Findings

Mobility and saturation velocity decrease with temperature above 300 K.

Saturation velocity exceeds 3x10^7 cm/s at low carrier density.

Intrinsic graphene saturation velocity could be more than twice the observed value.

Abstract

We examine mobility and saturation velocity in graphene on SiO2 above room temperature (300-500 K) and at high fields (~1 V/um). Data are analyzed with practical models including gated carriers, thermal generation, "puddle" charge, and Joule heating. Both mobility and saturation velocity decrease with rising temperature above 300 K, and with rising carrier density above 2x10^12 cm^-2. Saturation velocity is >3x10^7 cm/s at low carrier density, and remains greater than in Si up to 1.2x10^13 cm^-2. Transport appears primarily limited by the SiO2 substrate, but results suggest intrinsic graphene saturation velocity could be more than twice that observed here.