Silicon nitride gate dielectrics and bandgap engineering in graphene layers

TL;DR

This paper demonstrates that silicon nitride can serve as an effective, uniform gate dielectric in graphene transistors, enabling the study of electric field-induced bandgap modifications across different graphene layer configurations.

Contribution

It introduces silicon nitride as a reliable insulator for graphene transistors and models the electric field effects on bandgap and resistance in multilayer graphene.

Findings

Silicon nitride provides uniform coverage and preserves mobility in graphene transistors.

Maximum channel resistance at the Dirac point varies with electric field strength.

Estimated bandgap or overlap changes with electric field in multilayer graphene.

Abstract

We show that silicon nitride can provide uniform coverage of graphene in field-effect transistors while preserving the channel mobility. This insulator allowed us to study the maximum channel resistance at the Dirac (neutrality) point as a function of the strength of a perpendicular electric field in top-gated devices with different numbers of graphene layers. Using a simple model to account for surface potential variations (electron-hole puddles) near the Dirac point we estimate the field-induced band-gap or band-overlap in the different layers.