# STM/S Observations of Graphene on SiC(0001) Etched by H-plasma

## TL;DR

This study uses STM and spectroscopy to analyze how hydrogen plasma etching affects monolayer graphene on SiC(0001), revealing the formation of quasi-free-standing bilayer regions due to hydrogen intercalation.

## Contribution

It demonstrates that hydrogen plasma etching can induce decoupling of the buffer layer, creating stable bilayer graphene regions on SiC(0001).

## Key findings

- Formation of hexagonal nanopits and elevated regions after etching.
- Elevated regions show spectra indicating decoupled, quasi-free-standing bilayer graphene.
- Hydrogen intercalation passivates the SiC substrate, altering graphene's structure.

## Abstract

Monolayer graphene epitaxially grown on SiC(0001) was etched by H-plasma and studied by scanning tunneling microscopy and spectroscopy. The etching created partly hexagonal nanopits of monatomic depth as well as elevated regions with a height of about 0.12 nm which are stable at $T$ = 78 K. The symmetric tunnel spectrum about the Femi energy and the absence of a $6\times6$ corrugation on the elevated regions suggest that in these regions the carbon buffer layer is decoupled from the SiC substrate and quasi-free-standing bilayer graphene appears at originally monolayer graphene on the buffer layer. This is a result of passivation of the SiC substrate by intercalated hydrogen as in previous reports for graphene on SiC(0001) heat treated in atomic hydrogen.