Preserving the 7x7 surface reconstruction of clean Si(111) by graphene adsorption

TL;DR

This study demonstrates that graphene can be adsorbed onto the Si(111)-7x7 surface without disrupting its atomic reconstruction, providing insights into the interface chemistry relevant for graphene-based heterostructures.

Contribution

The paper combines experimental STM imaging and ab-initio calculations to show that graphene preserves the Si(111)-7x7 surface structure without chemical bonding.

Findings

Graphene adsorbs onto Si(111)-7x7 without altering its reconstruction.

No chemical bonding occurs between graphene and silicon atoms.

The atomistic configuration of the substrate remains intact under graphene.

Abstract

We employ room-temperature ultrahigh vacuum scanning tunneling microscopy (UHV STM) and {\em ab-initio} calculations to study graphene flakes that were adsorbed onto the Si(111)$-$7$\times$7 surface. The characteristic 7$\times$7 reconstruction of this semiconductor substrate can be resolved through graphene at all scanning biases, thus indicating that the atomistic configuration of the semiconducting substrate is not altered upon graphene adsorption. Large-scale {\em ab-initio} calculations confirm these experimental observations and point to a lack of chemical bonding among interfacial graphene and silicon atoms. Our work provides insight into atomic-scale chemistry between graphene and highly-reactive surfaces, directing future passivation and chemical interaction work in graphene-based heterostructures.