Nano-Objects Developing at Graphene/Silicon Carbide Interface

TL;DR

This study uses advanced microscopy techniques to reveal nano-objects and nano-cracks at the graphene/SiC interface, showing how these features influence electronic states and potentially impact device performance.

Contribution

It provides new insights into the nano-objects and nano-cracks at the graphene/SiC interface, highlighting their structure and electronic effects, which were previously not well understood.

Findings

Nano-objects are packed carbon nanotubes forming mesas at the interface.

Nano-cracks are covered by graphene and do not create electronic interface states.

Nano-objects may affect carrier mobility, unlike nano-cracks.

Abstract

We use scanning tunneling microscopy and spectroscopy to study epitaxial graphene grown on a C-face 4H-SiC(000-1) substrate. The results reveal amazing nano-objects at the graphene/SiC interface leading to electronic interface states. Their height profiles suggest that these objects are made of packed carbon nanotubes confined vertically and forming mesas at the SiC surface. We also find nano-cracks covered by the graphene layer that, surprisingly, is not broken, with no electronic interface state. Therefore, unlike the above nano-objects, these cracks should not affect the carrier mobility.