Hierarchy of Electronic Properties of Chemically Derived and Pristine Graphene Probed by Microwave Imaging

TL;DR

This study uses microwave impedance microscopy to analyze the local electronic properties of various forms of graphene, revealing inhomogeneities, defect effects, and validating contact quality, thus advancing understanding of graphene's electronic landscape.

Contribution

It provides a detailed hierarchy of electronic properties across different graphene types using microwave imaging, highlighting the effects of defects and chemical modifications.

Findings

Graphite oxide shows significant electronic inhomogeneity.

Chemical graphene exhibits reduced microwave signals due to residual defects.

Pristine graphene's signals align with a circuit model.

Abstract

Local electrical imaging using microwave impedance microscope is performed on graphene in different modalities, yielding a rich hierarchy of the local conductivity. The low-conductivity graphite oxide and its derivatives show significant electronic inhomogeneity. For the conductive chemical graphene, the residual defects lead to a systematic reduction of the microwave signals. In contrast, the signals on pristine graphene agree well with a lumped-element circuit model. The local impedance information can also be used to verify the electrical contact between overlapped graphene pieces.