Current Saturation and Surface Polar Phonon Scattering in Graphene

TL;DR

This paper investigates how substrate-induced surface polar phonons and self-heating affect charge transport and current saturation in graphene devices, offering insights for optimizing high-bias performance.

Contribution

It provides a detailed analysis of surface polar phonon scattering and self-heating effects on graphene mobility and current saturation, with practical device optimization suggestions.

Findings

Surface polar phonon scattering significantly reduces mobility at low bias.

Self-heating is crucial for understanding current saturation at high bias.

Optimizing device cooling can substantially increase high bias current capacity.

Abstract

We present a study of transport in graphene devices on polar insulating substrates using a tight-binding model. The mobility is computed using a multiband Boltzmann treatment. We provide the scaling of the surface polar phonon contribution to the low-field mobility with carrier density, temperature, and distance from the substrate. At high bias, we find that graphene self-heating effect is essential to account for the observed saturated current behavior. We predict that by optimizing the device cooling, the high bias currents can be significantly enhanced.