Gate-independent energy gap in non-covalently intercalated bilayer graphene on SiC(0001)

TL;DR

This study demonstrates that non-covalent intercalation of metals in bilayer graphene on SiC(0001) can reliably induce a stable energy gap, independent of gate voltage, offering a promising route for graphene-based electronic devices.

Contribution

It reveals a novel method to engineer a stable energy gap in bilayer graphene via non-covalent intercalation, unaffected by gate voltage variations.

Findings

Energy gap of 0.12-0.25 eV can be engineered in graphene.

The gap remains almost independent of gate voltage up to 1 V/nm.

The mechanism differs for transition metals and alkali metals.

Abstract

Our first-principles calculations show that an energy gap around 0.12-0.25 eV can be engineered in epitaxial graphene on SiC(0001) through the non-covalent intercalation of transition- or alkali-metals, yet originated from the distinct mechanisms. The former is attributed to the combined effects of metal induced perpendicular electric field and interaction while the latter is solely attributed to the built-in electric field. A great advantage of this scheme is that the gap size is almost independent of the gate voltage up to 1 V/nm, thus reserving the electric means to tune the Fermi level of graphene when configured as field-effect transistors. Given the recent progress in experimental techniques on the intercalated graphene, our findings provide a practical way to incorporate the graphene with the current semiconductor industry.