# Ab initio Study of Graphene on SiC

## TL;DR

This study uses density-functional calculations to analyze the bonding and electronic properties of graphene layers on SiC substrates, revealing new insights into the nature of the first carbon layer and the electronic spectrum.

## Contribution

It demonstrates that the first carbon layer is covalently bonded to SiC, challenging previous assumptions, and clarifies the electronic behavior of subsequent graphene layers.

## Key findings

- First carbon layer covalently bonded to substrate
- Graphene spectrum appears with second layer
- Interface properties differ between Si- and C-terminated surfaces

## Abstract

Employing density-functional calculations we study single and double graphene layers on Si- and C-terminated 1x1-6H-SiC surfaces. We show that, in contrast to earlier assumptions, the first carbon layer is covalently bonded to the substrate, and cannot be responsible for the graphene-type electronic spectrum observed experimentally. The characteristic spectrum of free-standing graphene appears with the second carbon layer, which exhibits a weak van der Waals bonding to the underlying structure. For Si-terminated substrate, the interface is metallic, whereas on C-face it is semiconducting or semimetallic for single or double graphene coverage, respectively.