Graphene nanoribbons: relevance of etching process

TL;DR

This paper compares two common etching techniques for graphene nanoribbons, revealing that plasma ashing causes more edge defects and transport instabilities than reactive ion etching, impacting electronic properties.

Contribution

It provides a comparative analysis of oxygen plasma ashing and RIE etching, highlighting how different processes affect defect formation and electronic stability in graphene nanoribbons.

Findings

Plasma ashing introduces more edge defects.

Defects lead to transport instabilities.

RIE results in fewer edge defects.

Abstract

Most graphene nanoribbons in the experimental literature are patterned using plasma etching. Various etching processes induce different types of defects and do not necessarily result in the same electronic and structural ribbon properties. This study focuses on two frequently used etching techniques, namely oxygen plasma ashing and oxygen/argon reactive ion etching (RIE). Oxygen plasma ashing represents an alternative to RIE physical etching for sensitive substrates, as it is a more gentle chemical process. We find that plasma ashing creates defective graphene in the exposed trenches, resulting in instabilities in the ribbon transport. These are probably caused by more or larger localized states at the edges of the ashed device compared to the RIE defined device.